Showing posts with label Java Concurrent. Show all posts
Showing posts with label Java Concurrent. Show all posts

Friday, March 14, 2014

Create animation on SurfaceView in background Thread

Last post "Simple SurfaceView example" draw bitmap in surfaceCreated() callback. In this step, a customized Thread, MyThread, is implemented to draw the bitmap running across screen in background thread.


MyThread.java
package com.example.androidsurfaceview;

import android.graphics.Canvas;

public class MyThread extends Thread {
 
 MySurfaceView myView;
 private boolean running = false;

 public MyThread(MySurfaceView view) {
  myView = view;
 }
 
 public void setRunning(boolean run) {
        running = run;    
 }

 @Override
 public void run() {
  while(running){
   
   Canvas canvas = myView.getHolder().lockCanvas();
   
   if(canvas != null){
    synchronized (myView.getHolder()) {
     myView.drawSomething(canvas);
    }
    myView.getHolder().unlockCanvasAndPost(canvas);
   }
   
   try {
    sleep(30);
   } catch (InterruptedException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
   }
   
  }
 }

}

Modify MySurfaceView.java in last post.
package com.example.androidsurfaceview;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.util.AttributeSet;
import android.view.SurfaceHolder;
import android.view.SurfaceView;

public class MySurfaceView extends SurfaceView {
 
    private SurfaceHolder surfaceHolder;
    private Bitmap bmpIcon;
    private MyThread myThread;
    int xPos = 0;
    int yPos = 0;
    int deltaX = 5;
    int deltaY = 5;
    int iconWidth;
    int iconHeight;

 public MySurfaceView(Context context) {
  super(context);
  init();
 }

 public MySurfaceView(Context context, 
   AttributeSet attrs) {
  super(context, attrs);
  init();
 }

 public MySurfaceView(Context context, 
   AttributeSet attrs, int defStyle) {
  super(context, attrs, defStyle);
  init();
 }
 
 private void init(){
  
  myThread = new MyThread(this);
  
  surfaceHolder = getHolder();
  bmpIcon = BitmapFactory.decodeResource(getResources(), 
    R.drawable.ic_launcher);

  iconWidth = bmpIcon.getWidth();
  iconHeight = bmpIcon.getHeight();
  
  surfaceHolder.addCallback(new SurfaceHolder.Callback(){

   @Override
   public void surfaceCreated(SurfaceHolder holder) {
    myThread.setRunning(true);
    myThread.start();
   }

   @Override
   public void surfaceChanged(SurfaceHolder holder, 
     int format, int width, int height) {
    // TODO Auto-generated method stub
    
   }

   @Override
   public void surfaceDestroyed(SurfaceHolder holder) {
    boolean retry = true;
                myThread.setRunning(false);
                while (retry) {
                       try {
                             myThread.join();
                             retry = false;
                       } catch (InterruptedException e) {
                       }
                }
   }});
 }

 protected void drawSomething(Canvas canvas) {
  canvas.drawColor(Color.BLACK);
        canvas.drawBitmap(bmpIcon, 
          getWidth()/2, getHeight()/2, null);
        
        xPos += deltaX;
        if(deltaX > 0){
         if(xPos >= getWidth() - iconWidth){
             deltaX *= -1;
            }
        }else{
         if(xPos <= 0){
             deltaX *= -1;
            }
        }
        
        yPos += deltaY;
        if(deltaY > 0){
         if(yPos >= getHeight() - iconHeight){
             deltaY *= -1;
            }
        }else{
         if(yPos <= 0){
             deltaY *= -1;
            }
        }

        canvas.drawColor(Color.BLACK);
        canvas.drawBitmap(bmpIcon, 
          xPos, yPos, null);

 }

}

Other files, /res/layout/activity_main.xml and MainActivity.java, refer to last post.

download filesDownload the files.

Next:
Draw bitmap programmatically for SurfaceView

Monday, March 3, 2014

Solve Producer–consumer problem with wait() and notifyAll()

It's a example to solve the Producer–consumer problem with wait() and notifyAll().

In computing, the producer–consumer problem (also known as the bounded-buffer problem) is a classic example of a multi-process synchronization problem. The problem describes two processes, the producer and the consumer, who share a common, fixed-size buffer used as a queue. The producer's job is to generate a piece of data, put it into the buffer and start again. At the same time, the consumer is consuming the data (i.e., removing it from the buffer) one piece at a time. The problem is to make sure that the producer won't try to add data into the buffer if it's full and that the consumer won't try to remove data from an empty buffer. ~ http://en.wikipedia.org/wiki/Producer-consumer

Solve Producer–consumer problem
Solve Producer–consumer problem

package com.example.androidthread;

import java.util.LinkedList;
import java.util.Random;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;
import android.app.Activity;

public class MainActivity extends Activity {

 Button buttonStart;
 TextView textInfoProducer, textInfoConsumer;

 String infoMsgProducer;
 String infoMsgConsumer;

 ShareClass shareObj = new ShareClass();
 long startingTime;

 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);
  buttonStart = (Button) findViewById(R.id.buttonstart);
  textInfoProducer = (TextView) findViewById(R.id.infoproducer);
  textInfoConsumer = (TextView) findViewById(R.id.infoconsumer);

  buttonStart.setOnClickListener(new OnClickListener() {

   @Override
   public void onClick(View arg0) {

    infoMsgProducer = "Producer\n";
    infoMsgConsumer = "Consumer\n";

    Thread threadProducer = new Thread(new Runnable() {

     @Override
     public void run() {
      
      int ele = 0;
      Random random = new Random();

      while (true) {
       String strEle = String.valueOf(ele);
       infoMsgProducer += strEle + "\n";
       
       MainActivity.this.runOnUiThread(new Runnable() {
        
        @Override
        public void run() {
         textInfoProducer.setText(infoMsgProducer);
        }
       });
       
       shareObj.produce(String.valueOf(ele));
       long randomDelay = 500 + random.nextInt(1000);
       
       try {
        Thread.sleep(randomDelay);
       } catch (InterruptedException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
       }
       ele++;
      }
     }
    });

    Thread threadConsumer = new Thread(new Runnable() {

     @Override
     public void run() {

      while (true) {
       Random random = new Random();

       while (true) {
        infoMsgConsumer += shareObj.consume() + "\n";
        
        MainActivity.this.runOnUiThread(new Runnable() {

         @Override
         public void run() {
          textInfoConsumer.setText(infoMsgConsumer);
         }});
        
        long randomDelay = 500 + random.nextInt(1000);
        
        try {
         Thread.sleep(randomDelay);
        } catch (InterruptedException e) {
         // TODO Auto-generated catch block
         e.printStackTrace();
        }
       }
      }
     }
    });
    
    startingTime = System.currentTimeMillis();
    threadProducer.start();
    threadConsumer.start();
   }
  });

 }

 public class ShareClass {

  final int BUFFER_MAX = 5;
  LinkedList<String> buffer;
  
  ShareClass(){
   buffer = new LinkedList<String>();
  }
  
  public synchronized void produce(String element){
   
   while(buffer.size() == BUFFER_MAX){
    try {
     wait();
    } catch (InterruptedException e) {
     // TODO Auto-generated catch block
     e.printStackTrace();
    }
   }
   buffer.offer(element);
   
   notifyAll();
  }
  
  public synchronized String consume(){
   
   while(buffer.size() == 0){
    try {
     wait();
    } catch (InterruptedException e) {
     // TODO Auto-generated catch block
     e.printStackTrace();
    }
   }
   
   String element = buffer.poll();
   notifyAll();
   return element;
  }
 }

}

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".MainActivity" >

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"
        android:autoLink="web"
        android:text="http://android-er.blogspot.com/"
        android:textStyle="bold" />

    <Button
        android:id="@+id/buttonstart"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="start()" />

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="horizontal" >

        <TextView
            android:id="@+id/infoproducer"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1" />

        <TextView
            android:id="@+id/infoconsumer"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1" />
        
    </LinearLayout>

</LinearLayout>




- More example about Thread

Friday, February 28, 2014

Example of using Lock/ReentrantLock

java.util.concurrent.locks.Lock implementations provide more extensive locking operations than can be obtained using synchronized methods and statements.
java.util.concurrent.locks.ReentrantLock is a reentrant mutual exclusion Lock with the same basic behavior and semantics as the implicit monitor lock accessed using synchronized methods and statements, but with extended capabilities.

This example have the same function of the More example of Synchronized Statements with separate objects for locking (the 2nd example), implement with Lock.


package com.example.androidthread;

import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;
import android.app.Activity;

public class MainActivity extends Activity {

 Button buttonStart;
 TextView textInfoA, textInfoB, textInfoC, textInfoD;
 TextView textDuration1, textDuration2;
 TextView textDuration3, textDuration4;

 String infoMsgA;
 String infoMsgB;
 String infoMsgC;
 String infoMsgD;

 ShareClass shareObj = new ShareClass(10);
 long startingTime;

 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);
  buttonStart = (Button) findViewById(R.id.buttonstart);
  textInfoA = (TextView) findViewById(R.id.infoa);
  textInfoB = (TextView) findViewById(R.id.infob);
  textInfoC = (TextView) findViewById(R.id.infoc);
  textInfoD = (TextView) findViewById(R.id.infod);
  textDuration1 = (TextView) findViewById(R.id.duration1);
  textDuration2 = (TextView) findViewById(R.id.duration2);
  textDuration3 = (TextView) findViewById(R.id.duration3);
  textDuration4 = (TextView) findViewById(R.id.duration4);

  buttonStart.setOnClickListener(new OnClickListener() {

   @Override
   public void onClick(View arg0) {

    infoMsgA = "Thread A\n";
    infoMsgB = "Thread B\n";
    infoMsgC = "Thread C\n";
    infoMsgD = "Thread D\n";
    textInfoA.setText(infoMsgA);
    textInfoB.setText(infoMsgB);
    textInfoC.setText(infoMsgC);
    textInfoD.setText(infoMsgD);

    Thread thread1 = new Thread(new Runnable() {

     boolean stop = false;

     @Override
     public void run() {

      while (!stop) {
       if (shareObj.getCounter1() > 0) {
        
        //caution:
        //shareObj.counter1 may change here

        infoMsgA += "A 1: "
          + shareObj.delayDecCounter1(500) + "\n";

        MainActivity.this.runOnUiThread(new Runnable() {

         @Override
         public void run() {
          textInfoA.setText(infoMsgA);
         }

        });

       } else {
        stop = true;
        final long endTime1 = System.currentTimeMillis();
        MainActivity.this.runOnUiThread(new Runnable() {

         @Override
         public void run() {
          textDuration1.setText("Duration 1 (reference only): " 
            + (endTime1 - startingTime));
         }

        });
       }
      }
     }
    });

    Thread thread2 = new Thread(new Runnable() {

     boolean stop = false;

     @Override
     public void run() {

      while (!stop) {
       if (shareObj.getCounter2() > 0) {
        
        //caution:
        //shareObj.counter2 may change here

        infoMsgB += "B 2: "
          + shareObj.delayDecCounter2(500) + "\n";

        MainActivity.this.runOnUiThread(new Runnable() {

         @Override
         public void run() {
          textInfoB.setText(infoMsgB);
         }

        });

       } else {
        stop = true;
        final long endTime2 = System.currentTimeMillis();
        MainActivity.this.runOnUiThread(new Runnable() {

         @Override
         public void run() {
          textDuration2.setText("Duration 2 (reference only): " 
            + (endTime2 - startingTime));
         }

        });
       }
      }
     }
    });
    
    //
    Thread thread3 = new Thread(new Runnable() {

     boolean stop = false;

     @Override
     public void run() {

      while (!stop) {
       if (shareObj.getCounter1() > 0) {
        
        //caution:
        //shareObj.counter1 may change here

        infoMsgC += "C 1: "
          + shareObj.delayDecCounter1(200) + "\n";

        MainActivity.this.runOnUiThread(new Runnable() {

         @Override
         public void run() {
          textInfoC.setText(infoMsgC);
         }

        });

       } else {
        stop = true;
        final long endTime3 = System.currentTimeMillis();
        MainActivity.this.runOnUiThread(new Runnable() {

         @Override
         public void run() {
          textDuration3.setText("Duration 3 (reference only): " 
            + (endTime3 - startingTime));
         }

        });
       }
      }
     }
    });

    Thread thread4 = new Thread(new Runnable() {

     boolean stop = false;

     @Override
     public void run() {

      while (!stop) {
       if (shareObj.getCounter2() > 0) {
        
        //caution:
        //shareObj.counter2 may change here

        infoMsgD += "D 2: "
          + shareObj.delayDecCounter2(1100) + "\n";

        MainActivity.this.runOnUiThread(new Runnable() {

         @Override
         public void run() {
          textInfoD.setText(infoMsgD);
         }

        });

       } else {
        stop = true;
        final long endTime4 = System.currentTimeMillis();
        MainActivity.this.runOnUiThread(new Runnable() {

         @Override
         public void run() {
          textDuration4.setText("Duration 4 (reference only): " 
            + (endTime4 - startingTime));
         }

        });
       }
      }
     }
    });
    //
    
    startingTime = System.currentTimeMillis();
    thread1.start();
    thread2.start();
    thread3.start();
    thread4.start();
   }
  });

 }

 public class ShareClass {

  int counter1;
  int counter2;
  
  //Object lock1;
  //Object lock2;
  Lock lock1;
  Lock lock2;

  ShareClass(int c) {
   counter1 = c;
   counter2 = c;
   lock1 = new ReentrantLock();
   lock2 = new ReentrantLock();
  }

  public int getCounter1() {
   return counter1;
  }
  
  public int getCounter2() {
   return counter2;
  }

  public int delayDecCounter1(int delay) {
   
   //do something not access the share obj
   try {
    Thread.sleep(100);
   } catch (InterruptedException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
   }

   int tmpCounter;
   lock1.lock();
   try{
    tmpCounter = counter1;

    try {
     Thread.sleep(delay);
    } catch (InterruptedException e) {
     // TODO Auto-generated catch block
     e.printStackTrace();
    }

    tmpCounter--;
    counter1 = tmpCounter;
   }finally{
    lock1.unlock();
   }
   
   return tmpCounter;
   
  }
  
  public int delayDecCounter2(int delay) {
   
   //do something not access the share obj
   try {
    Thread.sleep(100);
   } catch (InterruptedException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
   }
   
   int tmpCounter;
   lock2.lock();
   try{
    tmpCounter = counter2;

    try {
     Thread.sleep(delay);
    } catch (InterruptedException e) {
     // TODO Auto-generated catch block
     e.printStackTrace();
    }

    tmpCounter--;
    counter2 = tmpCounter;
   }finally{
    lock2.unlock();
   }
   
   return counter2;
   
  }
 }

}

The layout XML, refer to the former exercise of More example of Synchronized Statements with separate objects for locking.


- More example about Thread

Thursday, February 27, 2014

More example of Synchronized Statements with separate objects for locking

Last example compare between Synchronization with single lock object and separate lock objects, one-on-one; one thread access one object and another object access another object. This example demonstrate a more complicated case, two threads access one object, and other two thread access another object.

Synchronized Statements with single object, this.
package com.example.androidthread;

import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;
import android.app.Activity;

public class MainActivity extends Activity {

 Button buttonStart;
 TextView textInfoA, textInfoB, textInfoC, textInfoD;
 TextView textDuration1, textDuration2;
 TextView textDuration3, textDuration4;

 String infoMsgA;
 String infoMsgB;
 String infoMsgC;
 String infoMsgD;

 ShareClass shareObj = new ShareClass(10);
 long startingTime;

 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);
  buttonStart = (Button) findViewById(R.id.buttonstart);
  textInfoA = (TextView) findViewById(R.id.infoa);
  textInfoB = (TextView) findViewById(R.id.infob);
  textInfoC = (TextView) findViewById(R.id.infoc);
  textInfoD = (TextView) findViewById(R.id.infod);
  textDuration1 = (TextView) findViewById(R.id.duration1);
  textDuration2 = (TextView) findViewById(R.id.duration2);
  textDuration3 = (TextView) findViewById(R.id.duration3);
  textDuration4 = (TextView) findViewById(R.id.duration4);

  buttonStart.setOnClickListener(new OnClickListener() {

   @Override
   public void onClick(View arg0) {

    infoMsgA = "Thread A\n";
    infoMsgB = "Thread B\n";
    infoMsgC = "Thread C\n";
    infoMsgD = "Thread D\n";
    textInfoA.setText(infoMsgA);
    textInfoB.setText(infoMsgB);
    textInfoC.setText(infoMsgC);
    textInfoD.setText(infoMsgD);

    Thread thread1 = new Thread(new Runnable() {

     boolean stop = false;

     @Override
     public void run() {

      while (!stop) {
       if (shareObj.getCounter1() > 0) {
        
        //caution:
        //shareObj.counter1 may change here

        infoMsgA += "A 1: "
          + shareObj.delayDecCounter1(500) + "\n";

        MainActivity.this.runOnUiThread(new Runnable() {

         @Override
         public void run() {
          textInfoA.setText(infoMsgA);
         }

        });

       } else {
        stop = true;
        final long endTime1 = System.currentTimeMillis();
        MainActivity.this.runOnUiThread(new Runnable() {

         @Override
         public void run() {
          textDuration1.setText("Duration 1 (reference only): " 
            + (endTime1 - startingTime));
         }

        });
       }
      }
     }
    });

    Thread thread2 = new Thread(new Runnable() {

     boolean stop = false;

     @Override
     public void run() {

      while (!stop) {
       if (shareObj.getCounter2() > 0) {
        
        //caution:
        //shareObj.counter2 may change here

        infoMsgB += "B 2: "
          + shareObj.delayDecCounter2(500) + "\n";

        MainActivity.this.runOnUiThread(new Runnable() {

         @Override
         public void run() {
          textInfoB.setText(infoMsgB);
         }

        });

       } else {
        stop = true;
        final long endTime2 = System.currentTimeMillis();
        MainActivity.this.runOnUiThread(new Runnable() {

         @Override
         public void run() {
          textDuration2.setText("Duration 2 (reference only): " 
            + (endTime2 - startingTime));
         }

        });
       }
      }
     }
    });
    
    //
    Thread thread3 = new Thread(new Runnable() {

     boolean stop = false;

     @Override
     public void run() {

      while (!stop) {
       if (shareObj.getCounter1() > 0) {
        
        //caution:
        //shareObj.counter1 may change here

        infoMsgC += "C 1: "
          + shareObj.delayDecCounter1(200) + "\n";

        MainActivity.this.runOnUiThread(new Runnable() {

         @Override
         public void run() {
          textInfoC.setText(infoMsgC);
         }

        });

       } else {
        stop = true;
        final long endTime3 = System.currentTimeMillis();
        MainActivity.this.runOnUiThread(new Runnable() {

         @Override
         public void run() {
          textDuration3.setText("Duration 3 (reference only): " 
            + (endTime3 - startingTime));
         }

        });
       }
      }
     }
    });

    Thread thread4 = new Thread(new Runnable() {

     boolean stop = false;

     @Override
     public void run() {

      while (!stop) {
       if (shareObj.getCounter2() > 0) {
        
        //caution:
        //shareObj.counter2 may change here

        infoMsgD += "D 2: "
          + shareObj.delayDecCounter2(1100) + "\n";

        MainActivity.this.runOnUiThread(new Runnable() {

         @Override
         public void run() {
          textInfoD.setText(infoMsgD);
         }

        });

       } else {
        stop = true;
        final long endTime4 = System.currentTimeMillis();
        MainActivity.this.runOnUiThread(new Runnable() {

         @Override
         public void run() {
          textDuration4.setText("Duration 4 (reference only): " 
            + (endTime4 - startingTime));
         }

        });
       }
      }
     }
    });
    //
    
    startingTime = System.currentTimeMillis();
    thread1.start();
    thread2.start();
    thread3.start();
    thread4.start();
   }
  });

 }

 public class ShareClass {

  int counter1;
  int counter2;
  
  Object lock1;
  Object lock2;

  ShareClass(int c) {
   counter1 = c;
   counter2 = c;
   lock1 = new Object();
   lock2 = new Object();
  }

  public int getCounter1() {
   return counter1;
  }
  
  public int getCounter2() {
   return counter2;
  }

  public int delayDecCounter1(int delay) {
   
   //do something not access the share obj
   try {
    Thread.sleep(100);
   } catch (InterruptedException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
   }

   synchronized (this) {
    int tmpCounter = counter1;

    try {
     Thread.sleep(delay);
    } catch (InterruptedException e) {
     // TODO Auto-generated catch block
     e.printStackTrace();
    }

    tmpCounter--;
    counter1 = tmpCounter;
    
    return counter1;
   }
   
  }
  
  public int delayDecCounter2(int delay) {
   
   //do something not access the share obj
   try {
    Thread.sleep(100);
   } catch (InterruptedException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
   }

   synchronized (this) {
    int tmpCounter = counter2;

    try {
     Thread.sleep(delay);
    } catch (InterruptedException e) {
     // TODO Auto-generated catch block
     e.printStackTrace();
    }

    tmpCounter--;
    counter2 = tmpCounter;
    
    return counter2;
   }
   
  }
 }

}



Synchronized Statements with separate objects, lock1 and lock2.
package com.example.androidthread;

import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;
import android.app.Activity;

public class MainActivity extends Activity {

 Button buttonStart;
 TextView textInfoA, textInfoB, textInfoC, textInfoD;
 TextView textDuration1, textDuration2;
 TextView textDuration3, textDuration4;

 String infoMsgA;
 String infoMsgB;
 String infoMsgC;
 String infoMsgD;

 ShareClass shareObj = new ShareClass(10);
 long startingTime;

 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);
  buttonStart = (Button) findViewById(R.id.buttonstart);
  textInfoA = (TextView) findViewById(R.id.infoa);
  textInfoB = (TextView) findViewById(R.id.infob);
  textInfoC = (TextView) findViewById(R.id.infoc);
  textInfoD = (TextView) findViewById(R.id.infod);
  textDuration1 = (TextView) findViewById(R.id.duration1);
  textDuration2 = (TextView) findViewById(R.id.duration2);
  textDuration3 = (TextView) findViewById(R.id.duration3);
  textDuration4 = (TextView) findViewById(R.id.duration4);

  buttonStart.setOnClickListener(new OnClickListener() {

   @Override
   public void onClick(View arg0) {

    infoMsgA = "Thread A\n";
    infoMsgB = "Thread B\n";
    infoMsgC = "Thread C\n";
    infoMsgD = "Thread D\n";
    textInfoA.setText(infoMsgA);
    textInfoB.setText(infoMsgB);
    textInfoC.setText(infoMsgC);
    textInfoD.setText(infoMsgD);

    Thread thread1 = new Thread(new Runnable() {

     boolean stop = false;

     @Override
     public void run() {

      while (!stop) {
       if (shareObj.getCounter1() > 0) {
        
        //caution:
        //shareObj.counter1 may change here

        infoMsgA += "A 1: "
          + shareObj.delayDecCounter1(500) + "\n";

        MainActivity.this.runOnUiThread(new Runnable() {

         @Override
         public void run() {
          textInfoA.setText(infoMsgA);
         }

        });

       } else {
        stop = true;
        final long endTime1 = System.currentTimeMillis();
        MainActivity.this.runOnUiThread(new Runnable() {

         @Override
         public void run() {
          textDuration1.setText("Duration 1 (reference only): " 
            + (endTime1 - startingTime));
         }

        });
       }
      }
     }
    });

    Thread thread2 = new Thread(new Runnable() {

     boolean stop = false;

     @Override
     public void run() {

      while (!stop) {
       if (shareObj.getCounter2() > 0) {
        
        //caution:
        //shareObj.counter2 may change here

        infoMsgB += "B 2: "
          + shareObj.delayDecCounter2(500) + "\n";

        MainActivity.this.runOnUiThread(new Runnable() {

         @Override
         public void run() {
          textInfoB.setText(infoMsgB);
         }

        });

       } else {
        stop = true;
        final long endTime2 = System.currentTimeMillis();
        MainActivity.this.runOnUiThread(new Runnable() {

         @Override
         public void run() {
          textDuration2.setText("Duration 2 (reference only): " 
            + (endTime2 - startingTime));
         }

        });
       }
      }
     }
    });
    
    //
    Thread thread3 = new Thread(new Runnable() {

     boolean stop = false;

     @Override
     public void run() {

      while (!stop) {
       if (shareObj.getCounter1() > 0) {
        
        //caution:
        //shareObj.counter1 may change here

        infoMsgC += "C 1: "
          + shareObj.delayDecCounter1(200) + "\n";

        MainActivity.this.runOnUiThread(new Runnable() {

         @Override
         public void run() {
          textInfoC.setText(infoMsgC);
         }

        });

       } else {
        stop = true;
        final long endTime3 = System.currentTimeMillis();
        MainActivity.this.runOnUiThread(new Runnable() {

         @Override
         public void run() {
          textDuration3.setText("Duration 3 (reference only): " 
            + (endTime3 - startingTime));
         }

        });
       }
      }
     }
    });

    Thread thread4 = new Thread(new Runnable() {

     boolean stop = false;

     @Override
     public void run() {

      while (!stop) {
       if (shareObj.getCounter2() > 0) {
        
        //caution:
        //shareObj.counter2 may change here

        infoMsgD += "D 2: "
          + shareObj.delayDecCounter2(1100) + "\n";

        MainActivity.this.runOnUiThread(new Runnable() {

         @Override
         public void run() {
          textInfoD.setText(infoMsgD);
         }

        });

       } else {
        stop = true;
        final long endTime4 = System.currentTimeMillis();
        MainActivity.this.runOnUiThread(new Runnable() {

         @Override
         public void run() {
          textDuration4.setText("Duration 4 (reference only): " 
            + (endTime4 - startingTime));
         }

        });
       }
      }
     }
    });
    //
    
    startingTime = System.currentTimeMillis();
    thread1.start();
    thread2.start();
    thread3.start();
    thread4.start();
   }
  });

 }

 public class ShareClass {

  int counter1;
  int counter2;
  
  Object lock1;
  Object lock2;

  ShareClass(int c) {
   counter1 = c;
   counter2 = c;
   lock1 = new Object();
   lock2 = new Object();
  }

  public int getCounter1() {
   return counter1;
  }
  
  public int getCounter2() {
   return counter2;
  }

  public int delayDecCounter1(int delay) {
   
   //do something not access the share obj
   try {
    Thread.sleep(100);
   } catch (InterruptedException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
   }

   synchronized (lock1) {
    int tmpCounter = counter1;

    try {
     Thread.sleep(delay);
    } catch (InterruptedException e) {
     // TODO Auto-generated catch block
     e.printStackTrace();
    }

    tmpCounter--;
    counter1 = tmpCounter;
    
    return counter1;
   }
   
  }
  
  public int delayDecCounter2(int delay) {
   
   //do something not access the share obj
   try {
    Thread.sleep(100);
   } catch (InterruptedException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
   }

   synchronized (lock2) {
    int tmpCounter = counter2;

    try {
     Thread.sleep(delay);
    } catch (InterruptedException e) {
     // TODO Auto-generated catch block
     e.printStackTrace();
    }

    tmpCounter--;
    counter2 = tmpCounter;
    
    return counter2;
   }
   
  }
 }

}


<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".MainActivity" >

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"
        android:autoLink="web"
        android:text="http://android-er.blogspot.com/"
        android:textStyle="bold" />

    <Button
        android:id="@+id/buttonstart"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="start()" />

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal" >

        <TextView
            android:id="@+id/infoa"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1" />

        <TextView
            android:id="@+id/infob"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1" />
        
        <TextView
            android:id="@+id/infoc"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1" />

        <TextView
            android:id="@+id/infod"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1" />
    </LinearLayout>
    
    <TextView
        android:id="@+id/duration1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />
    <TextView
        android:id="@+id/duration2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />
    <TextView
        android:id="@+id/duration3"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />
    <TextView
        android:id="@+id/duration4"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />

</LinearLayout>




- More example about Thread

Synchronized Statements with separate objects for locking

This example compare how Synchronized Statements with single object vs separate objects.

Synchronized Statements with single object, this.
package com.example.androidthread;

import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;
import android.app.Activity;

public class MainActivity extends Activity {

 Button buttonStart;
 TextView textInfoA, textInfoB;
 TextView textDuration1, textDuration2;

 String infoMsgA;
 String infoMsgB;

 ShareClass shareObj = new ShareClass(10);
 long startingTime;

 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);
  buttonStart = (Button) findViewById(R.id.buttonstart);
  textInfoA = (TextView) findViewById(R.id.infoa);
  textInfoB = (TextView) findViewById(R.id.infob);
  textDuration1 = (TextView) findViewById(R.id.duration1);
  textDuration2 = (TextView) findViewById(R.id.duration2);

  buttonStart.setOnClickListener(new OnClickListener() {

   @Override
   public void onClick(View arg0) {

    infoMsgA = "Thread A\n";
    infoMsgB = "Thread B\n";
    textInfoA.setText(infoMsgA);
    textInfoB.setText(infoMsgB);

    Thread thread1 = new Thread(new Runnable() {

     boolean stop = false;

     @Override
     public void run() {

      while (!stop) {
       if (shareObj.getCounter1() > 0) {

        infoMsgA += "A 1: "
          + shareObj.delayDecCounter1(500) + "\n";

        MainActivity.this.runOnUiThread(new Runnable() {

         @Override
         public void run() {
          textInfoA.setText(infoMsgA);
         }

        });

       } else {
        stop = true;
        final long endTime1 = System.currentTimeMillis();
        MainActivity.this.runOnUiThread(new Runnable() {

         @Override
         public void run() {
          textDuration1.setText("Duration 1 (reference only): " 
            + (endTime1 - startingTime));
         }

        });
       }
      }
     }
    });

    Thread thread2 = new Thread(new Runnable() {

     boolean stop = false;

     @Override
     public void run() {

      while (!stop) {
       if (shareObj.getCounter2() > 0) {

        infoMsgB += "B 2: "
          + shareObj.delayDecCounter2(500) + "\n";

        MainActivity.this.runOnUiThread(new Runnable() {

         @Override
         public void run() {
          textInfoB.setText(infoMsgB);
         }

        });

       } else {
        stop = true;
        final long endTime2 = System.currentTimeMillis();
        MainActivity.this.runOnUiThread(new Runnable() {

         @Override
         public void run() {
          textDuration2.setText("Duration 2 (reference only): " 
            + (endTime2 - startingTime));
         }

        });
       }
      }
     }
    });
    
    startingTime = System.currentTimeMillis();
    thread1.start();
    thread2.start();
   }
  });

 }

 public class ShareClass {

  int counter1;
  int counter2;

  ShareClass(int c) {
   counter1 = c;
   counter2 = c;
  }

  public int getCounter1() {
   return counter1;
  }
  
  public int getCounter2() {
   return counter2;
  }

  public int delayDecCounter1(int delay) {
   
   //do something not access the share obj
   try {
    Thread.sleep(100);
   } catch (InterruptedException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
   }

   synchronized (this) {
    int tmpCounter = counter1;

    try {
     Thread.sleep(delay);
    } catch (InterruptedException e) {
     // TODO Auto-generated catch block
     e.printStackTrace();
    }

    tmpCounter--;
    counter1 = tmpCounter;
    
    return counter1;
   }
   
  }
  
  public int delayDecCounter2(int delay) {
   
   //do something not access the share obj
   try {
    Thread.sleep(100);
   } catch (InterruptedException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
   }

   synchronized (this) {
    int tmpCounter = counter2;

    try {
     Thread.sleep(delay);
    } catch (InterruptedException e) {
     // TODO Auto-generated catch block
     e.printStackTrace();
    }

    tmpCounter--;
    counter2 = tmpCounter;
    
    return counter2;
   }
   
  }
 }

}



Synchronized Statements with separate objects, lock1 and lock2.
package com.example.androidthread;

import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;
import android.app.Activity;

public class MainActivity extends Activity {

 Button buttonStart;
 TextView textInfoA, textInfoB;
 TextView textDuration1, textDuration2;

 String infoMsgA;
 String infoMsgB;

 ShareClass shareObj = new ShareClass(10);
 long startingTime;

 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);
  buttonStart = (Button) findViewById(R.id.buttonstart);
  textInfoA = (TextView) findViewById(R.id.infoa);
  textInfoB = (TextView) findViewById(R.id.infob);
  textDuration1 = (TextView) findViewById(R.id.duration1);
  textDuration2 = (TextView) findViewById(R.id.duration2);

  buttonStart.setOnClickListener(new OnClickListener() {

   @Override
   public void onClick(View arg0) {

    infoMsgA = "Thread A\n";
    infoMsgB = "Thread B\n";
    textInfoA.setText(infoMsgA);
    textInfoB.setText(infoMsgB);

    Thread thread1 = new Thread(new Runnable() {

     boolean stop = false;

     @Override
     public void run() {

      while (!stop) {
       if (shareObj.getCounter1() > 0) {

        infoMsgA += "A 1: "
          + shareObj.delayDecCounter1(500) + "\n";

        MainActivity.this.runOnUiThread(new Runnable() {

         @Override
         public void run() {
          textInfoA.setText(infoMsgA);
         }

        });

       } else {
        stop = true;
        final long endTime1 = System.currentTimeMillis();
        MainActivity.this.runOnUiThread(new Runnable() {

         @Override
         public void run() {
          textDuration1.setText("Duration 1 (reference only): " 
            + (endTime1 - startingTime));
         }

        });
       }
      }
     }
    });

    Thread thread2 = new Thread(new Runnable() {

     boolean stop = false;

     @Override
     public void run() {

      while (!stop) {
       if (shareObj.getCounter2() > 0) {

        infoMsgB += "B 2: "
          + shareObj.delayDecCounter2(500) + "\n";

        MainActivity.this.runOnUiThread(new Runnable() {

         @Override
         public void run() {
          textInfoB.setText(infoMsgB);
         }

        });

       } else {
        stop = true;
        final long endTime2 = System.currentTimeMillis();
        MainActivity.this.runOnUiThread(new Runnable() {

         @Override
         public void run() {
          textDuration2.setText("Duration 2 (reference only): " 
            + (endTime2 - startingTime));
         }

        });
       }
      }
     }
    });
    
    startingTime = System.currentTimeMillis();
    thread1.start();
    thread2.start();
   }
  });

 }

 public class ShareClass {

  int counter1;
  int counter2;
  
  Object lock1;
  Object lock2;

  ShareClass(int c) {
   counter1 = c;
   counter2 = c;
   lock1 = new Object();
   lock2 = new Object();
  }

  public int getCounter1() {
   return counter1;
  }
  
  public int getCounter2() {
   return counter2;
  }

  public int delayDecCounter1(int delay) {
   
   //do something not access the share obj
   try {
    Thread.sleep(100);
   } catch (InterruptedException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
   }

   synchronized (lock1) {
    int tmpCounter = counter1;

    try {
     Thread.sleep(delay);
    } catch (InterruptedException e) {
     // TODO Auto-generated catch block
     e.printStackTrace();
    }

    tmpCounter--;
    counter1 = tmpCounter;
    
    return counter1;
   }
   
  }
  
  public int delayDecCounter2(int delay) {
   
   //do something not access the share obj
   try {
    Thread.sleep(100);
   } catch (InterruptedException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
   }

   synchronized (lock2) {
    int tmpCounter = counter2;

    try {
     Thread.sleep(delay);
    } catch (InterruptedException e) {
     // TODO Auto-generated catch block
     e.printStackTrace();
    }

    tmpCounter--;
    counter2 = tmpCounter;
    
    return counter2;
   }
   
  }
 }

}


<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".MainActivity" >

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"
        android:autoLink="web"
        android:text="http://android-er.blogspot.com/"
        android:textStyle="bold" />

    <Button
        android:id="@+id/buttonstart"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="start()" />

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal" >

        <TextView
            android:id="@+id/infoa"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1" />

        <TextView
            android:id="@+id/infob"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1" />
    </LinearLayout>
    
    <TextView
        android:id="@+id/duration1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />
    <TextView
        android:id="@+id/duration2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />

</LinearLayout>

This example compare between Synchronization with single lock object and separate lock objects, one-on-one; one thread access one object and another object access another object. Next example demonstrate a more complicated case, two threads access one object, and other two thread access another object.


- More example about Thread

Wednesday, February 26, 2014

Share object between threads with Synchronized Statements

Last post show how to create synchronized code with Synchronized Method. Alternatively, we can synchronize block of code with Synchronized Statements.


Example code:
package com.example.androidthread;

import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;
import android.app.Activity;

public class MainActivity extends Activity {

 Button buttonStart;
 TextView textInfoA, textInfoB;

 String infoMsgA;
 String infoMsgB;

 ShareClass shareObj = new ShareClass(10);

 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);
  buttonStart = (Button) findViewById(R.id.buttonstart);
  textInfoA = (TextView) findViewById(R.id.infoa);
  textInfoB = (TextView) findViewById(R.id.infob);

  buttonStart.setOnClickListener(new OnClickListener() {

   @Override
   public void onClick(View arg0) {

    infoMsgA = "Thread A\n";
    infoMsgB = "Thread B\n";
    textInfoA.setText(infoMsgA);
    textInfoB.setText(infoMsgB);

    new Thread(new Runnable() {

     boolean stop = false;

     @Override
     public void run() {

      while (!stop) {
       if (shareObj.getCounter() > 0) {

        infoMsgA += "A: "
          + shareObj.delayDecCounter(2500) + "\n";
        
        try {
         Thread.sleep(3000);
        } catch (InterruptedException e) {
         // TODO Auto-generated catch block
         e.printStackTrace();
        }

        MainActivity.this.runOnUiThread(new Runnable() {

         @Override
         public void run() {
          textInfoA.setText(infoMsgA);
         }

        });

       } else {
        stop = true;
       }
      }
     }
    }).start();

    new Thread(new Runnable() {

     boolean stop = false;

     @Override
     public void run() {

      while (!stop) {
       if (shareObj.getCounter() > 0) {

        infoMsgB += "B: "
          + shareObj.delayDecCounter(500) + "\n";
        
        try {
         Thread.sleep(500);
        } catch (InterruptedException e) {
         // TODO Auto-generated catch block
         e.printStackTrace();
        }

        MainActivity.this.runOnUiThread(new Runnable() {

         @Override
         public void run() {
          textInfoB.setText(infoMsgB);
         }

        });

       } else {
        stop = true;
       }
      }
     }
    }).start();

   }
  });

 }

 public class ShareClass {

  int counter;

  ShareClass(int c) {
   counter = c;
  }

  public int getCounter() {
   return counter;
  }

  public int delayDecCounter(int delay) {
   
   //do something not access the share obj
   try {
    Thread.sleep(100);
   } catch (InterruptedException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
   }

   synchronized (this) {
    int tmpCounter = counter;

    try {
     Thread.sleep(delay);
    } catch (InterruptedException e) {
     // TODO Auto-generated catch block
     e.printStackTrace();
    }

    tmpCounter--;
    counter = tmpCounter;
    
    return counter;
   }
   
  }
 }

}


The layout XML, refer to last post.


- More example about Thread

Share object between threads with synchronized methods

This example show how to synchronize share object between threads with synchronized methods.

Share object between threads WITH synchronized method


Share object between threads WITHOUT synchronized method


package com.example.androidthread;

import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;
import android.app.Activity;

public class MainActivity extends Activity {

 Button buttonStart;
 TextView textInfoA, textInfoB;

 String infoMsgA;
 String infoMsgB;

 ShareClass shareObj = new ShareClass(10);

 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);
  buttonStart = (Button) findViewById(R.id.buttonstart);
  textInfoA = (TextView) findViewById(R.id.infoa);
  textInfoB = (TextView) findViewById(R.id.infob);

  buttonStart.setOnClickListener(new OnClickListener() {

   @Override
   public void onClick(View arg0) {

    infoMsgA = "Thread A\n";
    infoMsgB = "Thread B\n";
    textInfoA.setText(infoMsgA);
    textInfoB.setText(infoMsgB);

    new Thread(new Runnable() {

     boolean stop = false;

     @Override
     public void run() {

      while (!stop) {
       if (shareObj.getCounter() > 0) {

        infoMsgA += "A: "
          + shareObj.delayDecCounter(2500) + "\n";
        
        try {
         Thread.sleep(3000);
        } catch (InterruptedException e) {
         // TODO Auto-generated catch block
         e.printStackTrace();
        }

        MainActivity.this.runOnUiThread(new Runnable() {

         @Override
         public void run() {
          textInfoA.setText(infoMsgA);
         }

        });

       } else {
        stop = true;
       }
      }
     }
    }).start();

    new Thread(new Runnable() {

     boolean stop = false;

     @Override
     public void run() {

      while (!stop) {
       if (shareObj.getCounter() > 0) {

        infoMsgB += "B: "
          + shareObj.delayDecCounter(500) + "\n";
        
        try {
         Thread.sleep(500);
        } catch (InterruptedException e) {
         // TODO Auto-generated catch block
         e.printStackTrace();
        }

        MainActivity.this.runOnUiThread(new Runnable() {

         @Override
         public void run() {
          textInfoB.setText(infoMsgB);
         }

        });

       } else {
        stop = true;
       }
      }
     }
    }).start();

   }
  });

 }

 public class ShareClass {

  int counter;

  ShareClass(int c) {
   counter = c;
  }

  public int getCounter() {
   return counter;
  }

  public synchronized int delayDecCounter(int delay) {

   int tmpCounter = counter;

   try {
    Thread.sleep(delay);
   } catch (InterruptedException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
   }

   tmpCounter--;
   counter = tmpCounter;
   return counter;
  }
 }

}

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".MainActivity" >

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"
        android:autoLink="web"
        android:text="http://android-er.blogspot.com/"
        android:textStyle="bold" />

    <Button
        android:id="@+id/buttonstart"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="start()" />

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="with synchronized" />

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="horizontal" >

        <TextView
            android:id="@+id/infoa"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1" />

        <TextView
            android:id="@+id/infob"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1" />
    </LinearLayout>

</LinearLayout>

Next: Share object between threads with Synchronized Statements


- More example about Thread

Sunday, February 23, 2014

Runnable in background thread

This exercise show how to run a Runnable in background.
Runnable in background thread
Runnable in background thread

In this exercise, we need to check if the current thread is the main thread, or called UI thread. Using the code:

Looper.getMainLooper().getThread()==Thread.currentThread()

If it's true, means it's in main thread, otherwise it's in background thread.

The example show how to implement a Thread with Runnable object. And call its start() method to starts the new Thread of execution. Also notice that if you call its run() method, it will calls the run() method of the Runnable object directly, in current thread.

package com.example.androidthread;

import android.os.Bundle;
import android.os.Looper;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;
import android.app.Activity;

public class MainActivity extends Activity {
 
 Button buttonStart, buttonRun;
 TextView textInfo;

 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);
  buttonStart = (Button)findViewById(R.id.buttonstart);
  buttonRun = (Button)findViewById(R.id.buttonrun);
  textInfo = (TextView)findViewById(R.id.info);
  
  buttonStart.setOnClickListener(new OnClickListener(){

   @Override
   public void onClick(View arg0) {
    Thread thread = new Thread(new MyRunnable());
    thread.start(); //in background thread
   }});
  
  buttonRun.setOnClickListener(new OnClickListener(){

   @Override
   public void onClick(View arg0) {
    Thread thread = new Thread(new MyRunnable());
    thread.run(); //in current thread
   }});
 }

 private class MyRunnable implements Runnable {

  @Override
  public void run() {
   // check if it's run in main thread, or background thread
   if(Looper.getMainLooper().getThread()==Thread.currentThread()){
    //in main thread
    textInfo.setText("in main thread");
   }else{
    //in background thread

    runOnUiThread(new Runnable(){

     @Override
     public void run() {
      textInfo.setText("in background thread");
     }
     
    });
   }
  }
  
 }

}

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:orientation="vertical"
    tools:context=".MainActivity" >
    
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"
        android:autoLink="web"
        android:text="http://android-er.blogspot.com/"
        android:textStyle="bold" />
    <Button
        android:id="@+id/buttonstart"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="start()" />
    <Button
        android:id="@+id/buttonrun"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="run()" />
    <TextView
        android:id="@+id/info"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />

</LinearLayout>


More example about Thread:
Set name of Thread
Share object between threads with synchronized methods
Share object between threads with synchronized Statements
Synchronized Statements with separate lock object, I
Synchronized Statements with separate lock object, II
Example of using Lock/ReentrantLock
Solve Producer–consumer problem with wait() and notifyAll()