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