How to calculate remaining time of android phone battery? [duplicate]

Answer 1

-- Simplest and most easiest way to calculate remaining battery life :

MainActivity.java:

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.support.v7.app.AppCompatActivity;
import android.widget.TextView;


public class MainActivity extends AppCompatActivity {

    private TextView batteryPercent;
    private void getBatteryPercentage() {
        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;
                }
                batteryPercent.setText("Battery Level Remaining: " + level + "%");
            }
        };
        IntentFilter batteryLevelFilter = new IntentFilter(Intent.ACTION_BATTERY_CHANGED);
        registerReceiver(batteryLevelReceiver, batteryLevelFilter);
    }


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        batteryPercent = (TextView) this.findViewById(R.id.batteryLevel);
        getBatteryPercentage();
    }
}

xml file :