Как создать приложение Фонарик для Android

<shape xmlns:android="http://schemas.android.com/apk/res/android">
<gradient
    android:type="radial"
    android:startColor="#303030"
    android:endColor="#050505"
    android:gradientRadius="450"
    android:angle="050"/>
</shape>

В папку res/raw (создайте, если ее нет) загрузите звук щелчка по ссылке.

В макете экрана приложения такие компоненты:

<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:background="@drawable/flash_background"
    tools:context="info.fandroid.flashlight.MainActivity">

    <Switch
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/my_switch"
        android:layout_centerInParent="true"/>
</RelativeLayout>

Здесь используем экранный компонент Switch — переключатель, выравниваем его по центру.

Теперь код главного класса MainActivity.java:

package ...

import android.annotation.TargetApi;
import android.app.AlertDialog;
import android.content.DialogInterface;
import android.content.pm.PackageManager;
import android.graphics.SurfaceTexture;
import android.hardware.Camera;
import android.hardware.Camera.Parameters;
import android.media.AudioAttributes;
import android.media.AudioManager;
import android.media.SoundPool;
import android.os.Build;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.widget.CompoundButton;
import android.widget.Switch;

import java.io.IOException;
import java.util.List;

public class MainActivity extends AppCompatActivity implements SoundPool.OnLoadCompleteListener {

    private int sound;
    private SoundPool soundPool;
    private Camera camera;
    Parameters parameters;
    private Switch mySwitch;

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

        if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
            createSoundPoolWithBuilder();
        } else {
            createSoundPoolWithConstructor();
        }

        soundPool.setOnLoadCompleteListener(this);
        sound = soundPool.load(this, R.raw.click, 1);



        mySwitch = (Switch) findViewById(R.id.my_switch);
        mySwitch.setChecked(true);
        mySwitch.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
            @Override
            public void onCheckedChanged(CompoundButton compoundButton, boolean isChecked) {
                if (isChecked) {
                    setFlashLigthOn();
                } else {
                    setFlashLightOff();
                }
            }
        });

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

        if (!isCameraFlash) {
            showCameraAlert();
        } else {
            camera = Camera.open();
        }

    }
    private void showCameraAlert() {
        new AlertDialog.Builder(this)
                .setTitle(R.string.error_title)
                .setMessage(R.string.error_text)
                .setPositiveButton(R.string.exit_message, new DialogInterface.OnClickListener() {

                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        finish();
                    }
                })
                .setIcon(android.R.drawable.ic_dialog_alert)
                .show();
    }

    @TargetApi(Build.VERSION_CODES.LOLLIPOP)
    protected void createSoundPoolWithBuilder() {
        AudioAttributes attributes = new AudioAttributes.Builder()
                .setUsage(AudioAttributes.USAGE_GAME)
                .setContentType(AudioAttributes.CONTENT_TYPE_SONIFICATION)
                .build();

        soundPool = new SoundPool.Builder().setAudioAttributes(attributes).setMaxStreams(1).build();
    }

    @SuppressWarnings("deprecation")
    protected void createSoundPoolWithConstructor() {
        soundPool = new SoundPool(1, AudioManager.STREAM_MUSIC, 0);
    }

    private void setFlashLigthOn() {
        soundPool.play(sound, 1, 1, 0, 0, 1);

        new Thread(new Runnable() {
            @Override
            public void run() {
                if (camera != null) {
                    parameters = camera.getParameters();

                    if (parameters != null) {
                        List supportedFlashModes = parameters.getSupportedFlashModes();

                        if (supportedFlashModes.contains(Parameters.FLASH_MODE_TORCH)) {
                            parameters.setFlashMode(Parameters.FLASH_MODE_TORCH);
                        } else if (supportedFlashModes.contains(Parameters.FLASH_MODE_ON)) {
                            parameters.setFlashMode(Parameters.FLASH_MODE_ON);
                        } else camera = null;

                        if (camera != null) {
                            camera.setParameters(parameters);
                            camera.startPreview();
                            try {
                                camera.setPreviewTexture(new SurfaceTexture(0));
                            } catch (IOException e) {
                                e.printStackTrace();
                            }
                        }
                    }
                }
            }
        }).start();
    }

    private void setFlashLightOff() {
        soundPool.play(sound, 1, 1, 0, 0, 1);
        new Thread(new Runnable() {
            @Override
            public void run() {
                if (camera != null) {
                    parameters.setFlashMode(Parameters.FLASH_MODE_OFF);
                    camera.setParameters(parameters);
                    camera.stopPreview();
                }
            }
        }).start();
    }

    private void releaseCamera() {
        if (camera != null) {
            camera.release();
            camera = null;
        }
    }

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

    @Override
    protected void onPause() {
        super.onPause();
        releaseCamera();
        mySwitch.setChecked(false);
    }

    @Override
    protected void onResume() {
        super.onResume();
        if (camera == null) {
            camera = Camera.open();
        } else{
            setFlashLigthOn();
        }
        mySwitch.setChecked(true);
    }

    @Override
    public void onLoadComplete(SoundPool soundPool, int i, int i1) {

    }
}

private void showCameraAlert() {
      new AlertDialog.Builder( this)
                  .setTitle(R.string. error_title )
                  .setMessage(R.string. error_text )
                  .setPositiveButton(R.string. exit_message , new DialogInterface.OnClickListener() {


                         @Override
                         public void onClick(DialogInterface dialog, int which) {
                              finish();
                        }
                  })
                  .setIcon(android.R.drawable. ic_dialog_alert )
                  .show();
}

if (Build.VERSION. SDK_INT >= Build.VERSION_CODES. LOLLIPOP ) {
      createSoundPoolWithBuilder();
} else {
      createSoundPoolWithConstructor();
}
sp .setOnLoadCompleteListener( this);
sound = sp .load( this, R.raw. click , 1 );

private void setFlashlightOff() {
      sp .play( sound, 1, 1, 0, 0, 1);
      new Thread( new Runnable() {
             public void run() {
                   if( camera != null ) {
                         params .setFlashMode(Parameters. FLASH_MODE_OFF);
                         camera .setParameters( params);
                         camera .stopPreview();
                  }
            }
      }).start();
}

mySwitch .setOnCheckedChangeListener( new CompoundButton.OnCheckedChangeListener() {

      @Override
      public void onCheckedChanged(CompoundButton buttonView,
                                                 boolean isChecked) {

             if(isChecked){
                  setFlashlightOn();
            } else{
                  setFlashlightOff();
            }
      }
});