Find out battery level of android mobile

Today i am going explain how to calculate battery level of android mobile first of all are know with out battery we can't use mobile phone so battery is very important. Today i will display battery percentage on screen using android API any now i will explain battery level with example following code is my battery level finder.

I am using broadcast-receiver it is used when battery level changed it will update

activity_main.xml

<RelativeLayout 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"
    tools:context="com.example.battery.MainActivity" >



    <TextView
        android:id="@+id/textView2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignBaseline="@+id/textView1"
        android:layout_alignBottom="@+id/textView1"
        android:layout_marginLeft="20dp"
        android:layout_toRightOf="@+id/textView1" />


</RelativeLayout>




MainActivity.java



package com.example.battery;

import android.support.v7.app.ActionBarActivity;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.BatteryManager;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.TextView;

public class MainActivity extends ActionBarActivity {

TextView battery;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
battery =(TextView) findViewById(R.id.textView2);
batterylevelfinder();
}

private void batterylevelfinder() {
BroadcastReceiver batteryLevelReceiver = new BroadcastReceiver() {
        public void onReceive(Context context, Intent intent) {
            context.unregisterReceiver(this);
            int currentLevel = intent.getIntExtra(BatteryManager.EXTRA_LEVEL, -1);
            int scale = intent.getIntExtra(BatteryManager.EXTRA_SCALE, -1);
            int level = -1;
            if (currentLevel >= 0 && scale > 0) {
                level = (currentLevel * 100) / scale;
            }
            battery.setText("Battery Level Remaining: " + level + "%");
         
        }


    };
    IntentFilter batteryLevelFilter = new IntentFilter(Intent.ACTION_BATTERY_CHANGED);
    registerReceiver(batteryLevelReceiver, batteryLevelFilter);

}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
}

This main java file and i register broadcast-receiver for finding battery level when ever it changed it will display on screen using text-view following is my screenshot of project

This output of battery level