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Question

hi guys i've developed this flashlight app for android. The program first check if device is supporting flashlight or not; if not it will notify with an error message. I've launched it on nexus 4(android 4.4) and it works correctly but on my galaxy nexus(android 4.3)flashlight doesn't turn on and error message is not displayed

this is the code:

package com.androidhive.flashlight;

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.media.MediaPlayer;
import android.media.MediaPlayer.OnCompletionListener;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.ImageButton;

public class MainActivity extends Activity {

    ImageButton btnSwitch;

    private Camera camera;
    private boolean isFlashOn;
    private boolean hasFlash;
    Parameters params;
    MediaPlayer mp;

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

        // flash switch button
        btnSwitch = (ImageButton) findViewById(R.id.btnSwitch);

        /*
         * First check if device is supporting flashlight or not
         */
        hasFlash = getApplicationContext().getPackageManager()
                .hasSystemFeature(PackageManager.FEATURE_CAMERA_FLASH);

        if (!hasFlash) {
            // device doesn't support flash
            // Show alert message and close the application
            AlertDialog alert = new AlertDialog.Builder(MainActivity.this)
                    .create();
            alert.setTitle("Error");
            alert.setMessage("Sorry, your device doesn't support flash light!");
            alert.setButton("OK", new DialogInterface.OnClickListener() {
                public void onClick(DialogInterface dialog, int which) {
                    // closing the application
                    finish();
                }
            });
            alert.show();
            return;
        }

        // get the camera
        getCamera();

        // displaying button image
        toggleButtonImage();

        /*
         * Switch button click event to toggle flash on/off
         */
        btnSwitch.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                if (isFlashOn) {
                    // turn off flash
                    turnOffFlash();
                } else {
                    // turn on flash
                    turnOnFlash();
                }
            }
        });
    }

    /*
     * Get the camera
     */
    private void getCamera() {
        if (camera == null) {
            try {
                camera = Camera.open();
                params = camera.getParameters();
            } catch (RuntimeException e) {
                Log.e("Camera Error. Failed to Open. Error: ", e.getMessage());
            }
        }
    }

    /*
     * Turning On flash
     */
    private void turnOnFlash() {
        if (!isFlashOn) {
            if (camera == null || params == null) {
                return;
            }
            // play sound
            playSound();

            params = camera.getParameters();
            params.setFlashMode(Parameters.FLASH_MODE_TORCH);
            camera.setParameters(params);
            camera.startPreview();
            isFlashOn = true;

            // changing button/switch image
            toggleButtonImage();
        }

    }

    /*
     * Turning Off flash
     */
    private void turnOffFlash() {
        if (isFlashOn) {
            if (camera == null || params == null) {
                return;
            }
            // play sound
            playSound();

            params = camera.getParameters();
            params.setFlashMode(Parameters.FLASH_MODE_OFF);
            camera.setParameters(params);
            camera.stopPreview();
            isFlashOn = false;

            // changing button/switch image
            toggleButtonImage();
        }
    }

    /*
     * Playing sound
     * will play button toggle sound on flash on / off
     * */
    private void playSound(){
        if(isFlashOn){
            mp = MediaPlayer.create(MainActivity.this, R.raw.light_switch_off);
        }else{
            mp = MediaPlayer.create(MainActivity.this, R.raw.light_switch_on);
        }
        mp.setOnCompletionListener(new OnCompletionListener() {

            @Override
            public void onCompletion(MediaPlayer mp) {
                // TODO Auto-generated method stub
                mp.release();
            }
        }); 
        mp.start();
    }

    /*
     * Toggle switch button images
     * changing image states to on / off
     * */
    private void toggleButtonImage(){
        if(isFlashOn){
            btnSwitch.setImageResource(R.drawable.btn_switch_on);
        }else{
            btnSwitch.setImageResource(R.drawable.btn_switch_off);
        }
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
    }

    @Override
    protected void onPause() {
        super.onPause();

        // on pause turn off the flash
        turnOffFlash();
    }

    @Override
    protected void onRestart() {
        super.onRestart();
    }

    @Override
    protected void onResume() {
        super.onResume();

        // on resume turn on the flash
        if(hasFlash)
            turnOnFlash();
    }

    @Override
    protected void onStart() {
        super.onStart();

        // on starting the app get the camera params
        getCamera();
    }

    @Override
    protected void onStop() {
        super.onStop();

        // on stop release the camera
        if (camera != null) {
            camera.release();
            camera = null;
        }
    }

}

this is the androidmanifest.xml:

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.androidhive.flashlight"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="17" />

    <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.androidhive.flashlight.MainActivity"
            android:label="@string/app_name" 
            android:screenOrientation="portrait">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

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

</manifest>

can someone tell me please why doesn't it works on galaxy nexus? thanks

Answer 1

First add the following permission :

<!-- Allows access to the flashlight -->
<permission android:name="android.permission.FLASHLIGHT"
         android:permissionGroup="android.permission-group.HARDWARE_CONTROLS"
         android:protectionLevel="normal"
         android:label="@string/permlab_flashlight"
         android:description="@string/permdesc_flashlight" />

also for galaxy nexu you need to use a SurfaceView with size of 1dpx1dp to turn flashlight on. also you need to implement SurfaceHolder.Callback.

Check out this question .