CDACians India: Running a service in background on Android

Thursday, 5 January 2012

Running a service in background on Android

Here the code is generate to run some process in background through service. For example we are running the time in background and displaying it in the UI. The service coding will be in a seperate class MyService.java

MyService.java

package com.services.demo;

import java.util.Date;
import android.app.Service;
import android.content.Intent;
import android.os.Handler;
import android.os.IBinder;

public class MyService extends Service {
public static final String BROADCAST_ACTION = "com.services.demo.ServiceDemoActivity";
private final Handler handler = new Handler();
Intent intent;
int counter = 0;

@Override
public void onCreate() {
// Called on service created
intent = new Intent(BROADCAST_ACTION);
}

@Override
public void onDestroy() {
// Called on service stopped
}
@Override
public void onStart(Intent intent, int startid) {
int i = 0;
while (i < 101) {    if (i > 100) {
  this.onDestroy();
 } else {
  counter = i;
  i++;
  handler.removeCallbacks(sendUpdatesToUI);
        handler.postDelayed(sendUpdatesToUI, 1 * 1000); // 1 sec
 }
}

}

private Runnable sendUpdatesToUI = new Runnable() {
    public void run() {
        DisplayLoggingInfo();    
        handler.postDelayed(this, 1 * 1000); // 1 sec
    }
};

   private void DisplayLoggingInfo() {

    intent.putExtra("time", new Date().toLocaleString());
    intent.putExtra("counter", String.valueOf(counter));
    sendBroadcast(intent);
   }
public static boolean isRunning() {
return true;
}

@Override
public IBinder onBind(Intent intent) {
return null;
}
}

So for starting the service and stopping the service we will be using

Java

startService(new Intent(ServiceDemoActivity.this, MyService.class));
stopService(new Intent(ServiceDemoActivity.this, MyService.class));

For updating the UI we need to use the broadcast service. In that BroadcastReceiver we will update the UI

Java

private BroadcastReceiver broadcastReceiver = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
updateDate(intent);
}
};

private void updateDate(Intent intent) {
String time = intent.getStringExtra("time");
TextView date = (TextView) findViewById(R.id.date);
date.setText(time);
}


In the MyService.java the method DisplayLoggingInfo() will send the broadcast to the activity to update the UI, the UI xml code is

main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
 android:orientation="vertical"
 android:layout_width="fill_parent"
 android:layout_height="fill_parent"
 >
<TextView
 android:layout_width="fill_parent"
 android:layout_height="wrap_content"
 android:text="@string/hello"
 android:id="@+id/notification"
 />

 <TextView
 android:layout_width="fill_parent" android:id="@+id/date"
 android:layout_height="wrap_content" android:text="" android:gravity="center" android:textSize="20sp" android:padding="20dp"/>
 <Button android:id="@+id/stop" android:text="Stop Service" android:layout_width="wrap_content" android:layout_height="wrap_content" />
</LinearLayout>

If we are opening the application on the first time means, it will be like this