Android - Broadcast Receivers

Broadcast Receivers simply respond to broadcast messages from other applications or from the system itself. These messages are sometime called events or intents. For example, applications can also initiate broadcasts to let other applications know that some data has been downloaded to the device and is available for them to use, so this is broadcast receiver who will intercept this communication and will initiate appropriate action

There are following two important steps to make BroadcastReceiver works for the system broadcasted intents −

·        Creating the Broadcast Receiver.

·        Registering Broadcast Receiver

There is one additional steps in case you are going to implement your custom intents then you will have to create and broadcast those intents

actvity_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"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    app:layout_behavior="@string/appbar_scrolling_view_behavior"
    tools:showIn="@layout/activity_main" tools:context=".MainActivity">
   
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textAppearance="?android:attr/textAppearanceLarge"
        android:text="Welcome to Broadcast Receiver"
        android:id="@+id/textView"
        android:layout_gravity="center_horizontal" />
</LinearLayout>

MainActvity.Java

package com.sra.ani.broadcastreceiver;

import android.content.Intent;
import android.content.IntentFilter;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;


public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);
    registerReceiver(new MyBroadcast(),new IntentFilter(Intent.ACTION_BATTERY_CHANGED));
    }
}

MyBroadcast.Java

package com.sra.ani.broadcastreceiver;

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.widget.Toast;

/**
 * Created by Sra on 12/24/15.
 */
public class MyBroadcast extends BroadcastReceiver {
    @Override
    public void onReceive(Context context, Intent intent) {
        int bstatus=intent.getIntExtra("level",0);
        Toast.makeText(context, "Your Battery Status is : "+bstatus, Toast.LENGTH_SHORT).show();
    }
}

Output