My code contains two buttons and a TextView. When the program is running, by clicking on the start Thread button, a background Thread will be executed and at the same time a counter will be displayed in the TextView, and when you click on the stop Thread button, the background Thread will stop. My question is that I have not used the looper here and the counter value is displayed from the background thread in the TextView on the UI thread. How is this possible?
activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<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:gravity="center"
tools:context=".MainActivity">
<TextView
android:id="@+id/txtViewThreadCount"
android:hint="Thread Count"
android:textSize="30sp"
android:textColor="@color/black"
android:gravity="center"
android:padding="8dp"
android:layout_margin="10dp"
android:layout_width="match_parent"
android:layout_height="wrap_content"/>
<Button
android:id="@+id/btnStartThread"
android:layout_width="300dp"
android:layout_height="wrap_content"
android:textSize="30sp"
android:layout_marginTop="30dp"
android:text="Start Thread" />
<Button
android:id="@+id/btnStopThread"
android:layout_width="300dp"
android:layout_height="wrap_content"
android:textSize="30sp"
android:layout_marginTop="30dp"
android:text="Stop Thread" />
</LinearLayout>MainActivity.java
public class MainActivity extends AppCompatActivity implements View.OnClickListener{
//Fields
private static final String TAG = MainActivity.class.getSimpleName();
private TextView txtViewThreadCount;
private Button btnStartThread, btnStopThread;
private boolean stopLoop;
private int count = 0;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Log.e(TAG, "Thread id : "+Thread.currentThread().getId());
btnStartThread = findViewById(R.id.btnStartThread);
btnStopThread = findViewById(R.id.btnStopThread);
txtViewThreadCount = findViewById(R.id.txtViewThreadCount);
btnStartThread.setOnClickListener(this);
btnStopThread.setOnClickListener(this);
}
public void onClick(View view){
switch(view.getId()){
case R.id.btnStartThread:
stopLoop = true;
new Thread(new Runnable() {
@Override
public void run() {
while(stopLoop){
try {
Thread.sleep(1000);
count++;
} catch (InterruptedException e) {
Log.e(TAG,e.getMessage());
}
Log.e(TAG,"Thread id in while loop: "+Thread.currentThread().getId()+", Count: "+count);
txtViewThreadCount.setText(count+"");
}
}
}).start();
break;
case R.id.btnStopThread:
stopLoop = false;
break;
}
}
}
