Nexus 5を含むすべてのAndroidデバイスで動作するシンプルな懐中電灯アプリを作成しようとしています(これには、SurfaceView.
しかし、私のアプリは実行するたびにクラッシュし続けます。私の何が間違っていますか？
私の完全なコードは以下の通りです：
public class MainActivity extends Activity implements Callback {
//flag to detect flash is on or off
private boolean isLighOn = false;
private Camera camera;
private Button button;
private Parameters p;
private SurfaceHolder mHolder;
@Override
protected void onStart() {
super.onStart();
SurfaceView preview = (SurfaceView)findViewById(R.id.PREVIEW);
SurfaceHolder mHolder = preview.getHolder();
mHolder.addCallback(this);
}
@Override
protected void onStop() {
super.onStop();
if (camera != null) {
camera.release();
}
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Context context = this;
PackageManager pm = context.getPackageManager();
// if device support camera?
if (!pm.hasSystemFeature(PackageManager.FEATURE_CAMERA)) {
Log.e("err", "Device has no camera!");
return;
}
camera = Camera.open();
final Parameters p = camera.getParameters();
final ToggleButton tb = (ToggleButton) findViewById(R.id.toggle);
final ImageView image = (ImageView) findViewById(R.id.photo);
tb.setText(null);
tb.setTextOn(null);
tb.setTextOff(null);
tb.setBackgroundResource(R.drawable.check);
tb.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (tb.isChecked()) {
image.setImageResource(R.drawable.b);
turnOffFlash();
} else {
image.setImageResource(R.drawable.a);
}
}
});
}
@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;
}
private void turnOnFlash(){
Log.i("info", "torch is turn on!");
p.setFlashMode(Parameters.FLASH_MODE_TORCH);
camera.setParameters(p);
camera.startPreview();
isLighOn = true;
}
private void turnOffFlash(){
Log.i("info", "torch is turn off!");
p.setFlashMode(Parameters.FLASH_MODE_OFF);
camera.setParameters(p);
camera.stopPreview();
isLighOn = false;
}
@Override
public void surfaceChanged(SurfaceHolder holder,int format,int width,int height) {
}
@Override
public void surfaceCreated(SurfaceHolder holder){
mHolder = holder;
try {
Log.i("SurfaceHolder", "setting preview");
camera.setPreviewDisplay(mHolder);
} catch (IOException e){
e.printStackTrace();
}
}
@Override
public void surfaceDestroyed(SurfaceHolder holder){
Log.i("SurfaceHolder", "stopping preview");
camera.stopPreview();
mHolder = null;
}
}
私のレイアウトXMLファイルのコードは以下に掲載されています
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:gravity="center_horizontal" >
<ImageView
android:id="@+id/photo"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:src="@drawable/b"
android:scaleType="centerCrop"
android:contentDescription="@string/happy" />
<ToggleButton
android:id="@+id/toggle"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_centerHorizontal="true"
android:layout_margin="10dp"
android:layout_marginBottom="17dp"
android:background="@drawable/check"
android:focusable="false"
android:focusableInTouchMode="false" />
<SurfaceView
android:id="@+id/PREVIEW"
android:layout_width="1dp"
android:layout_height="1dp" />
</RelativeLayout>
ここに私のLogcatがあります
07-24 03:09:14.433: V/Provider/Settings(16560): invalidate [system]: current 64 != cached 0
07-24 03:09:14.436: V/Provider/Settings(16560): from db cache, name = sound_effects_enabled , value = 0
07-24 03:09:14.437: I/info(16560): torch is turn off!
07-24 03:09:14.437: D/AndroidRuntime(16560): Shutting down VM
07-24 03:09:14.437: W/dalvikvm(16560): threadid=1: thread exiting with uncaught exception (group=0x4112d9a8)
07-24 03:09:14.441: E/AndroidRuntime(16560): FATAL EXCEPTION: main
07-24 03:09:14.441: E/AndroidRuntime(16560): java.lang.NullPointerException
07-24 03:09:14.441: E/AndroidRuntime(16560): at com.example.torch.MainActivity.turnOffFlash(MainActivity.java:103)
07-24 03:09:14.441: E/AndroidRuntime(16560): at com.example.torch.MainActivity.access$0(MainActivity.java:100)
07-24 03:09:14.441: E/AndroidRuntime(16560): at com.example.torch.MainActivity$1.onClick(MainActivity.java:76)
07-24 03:09:14.441: E/AndroidRuntime(16560): at android.view.View.performClick(View.java:4211)
07-24 03:09:14.441: E/AndroidRuntime(16560): at android.widget.CompoundButton.performClick(CompoundButton.java:100)
07-24 03:09:14.441: E/AndroidRuntime(16560): at android.view.View$PerformClick.run(View.java:17446)
07-24 03:09:14.441: E/AndroidRuntime(16560): at android.os.Handler.handleCallback(Handler.java:725)
07-24 03:09:14.441: E/AndroidRuntime(16560): at android.os.Handler.dispatchMessage(Handler.java:92)
07-24 03:09:14.441: E/AndroidRuntime(16560): at android.os.Looper.loop(Looper.java:153)
07-24 03:09:14.441: E/AndroidRuntime(16560): at android.app.ActivityThread.main(ActivityThread.java:5297)
07-24 03:09:14.441: E/AndroidRuntime(16560): at java.lang.reflect.Method.invokeNative(Native Method)
07-24 03:09:14.441: E/AndroidRuntime(16560): at java.lang.reflect.Method.invoke(Method.java:511)
07-24 03:09:14.441: E/AndroidRuntime(16560): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:833)
07-24 03:09:14.441: E/AndroidRuntime(16560): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:600)
07-24 03:09:14.441: E/AndroidRuntime(16560): at dalvik.system.NativeStart.main(Native Method)