Java 接收广播接收器上的空对象引用
我使用两种活动,一种是主活动,另一种是摄像活动。在main活动中,我称之为startActivity(新意图(这个,CameraActivity))强> 现在,当照相机活动开始时,onCreate()是:Java 接收广播接收器上的空对象引用,java,android,android-intent,camera,Java,Android,Android Intent,Camera,我使用两种活动,一种是主活动,另一种是摄像活动。在main活动中,我称之为startActivity(新意图(这个,CameraActivity)) 现在,当照相机活动开始时,onCreate()是: @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.camera_preview);
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.camera_preview);
View myView= (View) findViewById(R.id.camera_previeww);
myView.setSystemUiVisibility(View.SYSTEM_UI_FLAG_HIDE_NAVIGATION);
cameraID= Camera.CameraInfo.CAMERA_FACING_FRONT;
mCamera=openCamera(cameraID);
mCamera.startPreview();
IntentFilter filter = new IntentFilter();
filter.addAction(Tabbed.BROADCAST_ACTION_TABBED);
LocalBroadcastManager bm = LocalBroadcastManager.getInstance(this);
bm.registerReceiver(mBroadcastReceiver, filter);
// Create our Preview view and set it as the content of our activity.
mPreview = new CameraPreview(this, mCamera);
FrameLayout preview = (FrameLayout) this.findViewById(R.id.camera_previeww);
preview.addView(mPreview);
}
openCamera(int-cameraID)方法是:
public Camera openCamera(int cameraIDD){
Camera c=null;
try{
c=Camera.open(cameraIDD);
}catch (Exception e){
Log.d("Camera Activity", e.getMessage());
}
return c;
}
我还使用了一个广播接收器,如:
private BroadcastReceiver mBroadcastReceiver = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
byte [] data=new byte[3];
if (intent.getAction().equals(Tabbed.BROADCAST_ACTION_TABBED)) {
data = intent.getByteArrayExtra(Tabbed.EXTRA_PARAM_BYTE);
}
if (data[FINGER]==MIDDLE_FINGER && data[TYPE]==SINGLE_TAP){
//switchCamera();
//releaseCamera();
//mCamera=Camera.open();
}
else if (data[FINGER]==MIDDLE_FINGER && data[TYPE]==DOUBLE_TAP){
// HAVE TO GO BACK
kill_activity();
}
else if (data[FINGER]==INDEX_FINGER && data[TYPE]==SINGLE_TAP){
mCamera.takePicture(null, null, mPicture);
}
// kill activity
}
};
以及其他一些方法:
@Override
protected void onPause() {
super.onPause();
//releaseCamera(); // release the camera immediately on pause event
}
private void releaseCamera(){
if (mCamera != null){
mCamera.release(); // release the camera for other applications
mCamera = null;
}
}
void kill_activity()
{
mCamera.stopPreview();
mCamera.setPreviewCallback(null);
releaseCamera();
finish();
}
以下是坠机事件:
FATAL EXCEPTION: main
Process: com.etu.goglove, PID: 6008
java.lang.NullPointerException: Attempt to invoke virtual method 'void android.hardware.Camera.takePicture(android.hardware.Camera$ShutterCallback, android.hardware.Camera$PictureCallback, android.hardware.Camera$PictureCallback)' on a null object reference
at com.etu.goglove.CameraActivity$2.onReceive(CameraActivity.java:155)
at android.support.v4.content.LocalBroadcastManager.executePendingBroadcasts(LocalBroadcastManager.java:297)
at android.support.v4.content.LocalBroadcastManager.access$000(LocalBroadcastManager.java:46)
at android.support.v4.content.LocalBroadcastManager$1.handleMessage(LocalBroadcastManager.java:116)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6119)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)
有了这些,当我收到广播意向时,我正试图拍一张照片。所以,在我的活动开始后,我打开mCamera,当我收到一个意向时,我会拍照片或者回来。在第一时间,我可以拍照,然后我完成我的活动。如果我尝试从mainActivity重新启动cameraActivity,调用startActivity(intent),在onCreate()中,相机是打开的,并且不是空的(通过调试器检查),但是这次,当我进入onReceive()方法时,mCamera总是空的,因此我在mCamera上得到一个空的对象引用!(当我试着做mCamera.takePicture()时)不知道如何
谢谢 若要在第155行的CameraActivity.java中发布崩溃日志崩溃,请在code@Gautam是的,我知道它在那里坠毁了。但是为什么呢?当我进入onCreate()时,mCamera不是null,当我进入onReceive()时,它是null。我无法理解…我应该从中理解什么…?添加意图=在receiverNothing中为null我得到的意图是好的,但当我进入onReceive方法时,mCamera立即变为null
private BroadcastReceiver mBroadcastReceiver = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
byte [] data=new byte[3];
if (intent!=null && intent.getAction().equals(Tabbed.BROADCAST_ACTION_TABBED)) {
data = intent.getByteArrayExtra(Tabbed.EXTRA_PARAM_BYTE);
if (data[FINGER]==MIDDLE_FINGER && data[TYPE]==SINGLE_TAP){
//switchCamera();
//releaseCamera();
//mCamera=Camera.open();
}
else if (data[FINGER]==MIDDLE_FINGER && data[TYPE]==DOUBLE_TAP){
// HAVE TO GO BACK
kill_activity();
}
else if (data[FINGER]==INDEX_FINGER && data[TYPE]==SINGLE_TAP){
mCamera.takePicture(null, null, mPicture);
}
}
// kill activity
}
};