Android Flashlight Application Tutorial

In this Android tutorial let us learn about how to create a nice small Android app which will help double your Android device as a flashlight too. It would be handy to have this flashlight app in our Android phone. Instead of downloading an app from the Google play store, wouldn’t it be nice if we develop it ourselves.

This is a simple app, all we are going to do is control the camera’s flashlight. In our app we will have a toggle switch to On and Off the camera flash. That’s it.

Step 1: Permission to use Camera

In the Android manifest file, add two lines as below to get permission for the app to use the device camera.

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.javapapers.android.androidflashlight.app" >

    <uses-permission android:name="android.permission.CAMERA" />
    <uses-feature android:name="android.hardware.camera" />

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name="com.javapapers.android.androidflashlight.app.FlashlightActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>
</manifest>

Step 2: Flashlight Control Layout

The layout will have one toggle switch which will control the flashlight on and off state. We will use two different image for on and off state. You can take it from the download zip file link give below.

<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:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:background="@drawable/light_control_background"
    tools:context="com.javapapers.android.androidflashlight.app.FlashlightActivity">
    <ImageButton
        android:id="@+id/flashlightSwitch"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="100dip"
        android:src="@drawable/light_off"
        android:background="@null"
        android:contentDescription="@null"
        />
</RelativeLayout>

Step 3: Android Activity

Important steps in the activity are,

• check if camera is present in the device before proceeding
• Instantiate Camera and get its parameters
• Toggle the Camera’s flashlight state using its parameter FlashMode (FLASH_MODE_TORCH | FLASH_MODE_OFF)

package com.javapapers.android.androidflashlight.app;
import android.os.Bundle;
import android.app.Activity;
import android.app.AlertDialog;
import android.content.DialogInterface;
import android.content.pm.PackageManager;
import android.hardware.Camera;
import android.hardware.Camera.Parameters;
import android.view.View;
import android.widget.ImageButton;

public class FlashlightActivity extends Activity {

    private Camera camera;
    ImageButton flashlightSwitchImg;
    private boolean isFlashlightOn;
    Parameters params;

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

        // flashlight on off Image
        flashlightSwitchImg = (ImageButton) findViewById(R.id.flashlightSwitch);

        boolean isCameraFlash = getApplicationContext().getPackageManager()
                .hasSystemFeature(PackageManager.FEATURE_CAMERA_FLASH);

        if (!isCameraFlash) {
            showNoCameraAlert();
        } else {
            camera = Camera.open();
            params = camera.getParameters();
        }

        flashlightSwitchImg.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (isFlashlightOn) {
                    setFlashlightOff();
                } else {
                    setFlashlightOn();
                }
            }
        });
    }

    private void showNoCameraAlert(){
        new AlertDialog.Builder(this)
                .setTitle("Error: No Camera Flash!")
                .setMessage("Camera flashlight not available in this Android device!")
                .setPositiveButton(android.R.string.yes, new DialogInterface.OnClickListener() {
                    public void onClick(DialogInterface dialog, int which) {
                        finish(); // close the Android app
                    }
                })
                .setIcon(android.R.drawable.ic_dialog_alert)
                .show();
        return;
    }
    private void setFlashlightOn() {
       params = camera.getParameters();
       params.setFlashMode(Parameters.FLASH_MODE_TORCH);
       camera.setParameters(params);
       camera.startPreview();
       isFlashlightOn = true;
       flashlightSwitchImg.setImageResource(R.drawable.light_on);
    }

    private void setFlashlightOff() {
        params.setFlashMode(Parameters.FLASH_MODE_OFF);
        camera.setParameters(params);
        camera.stopPreview();
        isFlashlightOn = false;
        flashlightSwitchImg.setImageResource(R.drawable.light_off);
    }

    @Override
    protected void onStop() {
        super.onStop();
        if (camera != null) {
            camera.release();
            camera = null;
        }
    }
}

Download the Android Flashlight Application

AndroidFlashlight