我实现了像这样的ToolbarCapture活动：
public class ToolbarCaptureActivity extends AppCompatActivity {
private CaptureManager capture;
private CompoundBarcodeView barcodeScannerView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.capture_appcompat);
Toolbar toolbar = (Toolbar) findViewById(R.id.my_awesome_toolbar);
toolbar.setTitle("Scan Barcode");
setSupportActionBar(toolbar);
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
barcodeScannerView = (CompoundBarcodeView)findViewById(R.id.zxing_barcode_scanner);
capture = new CaptureManager(this, barcodeScannerView);
capture.initializeFromIntent(getIntent(), savedInstanceState);
capture.decode();
}
@Override
protected void onResume() {
super.onResume();
capture.onResume();
}
@Override
protected void onPause() {
super.onPause();
capture.onPause();
}
@Override
protected void onDestroy() {
super.onDestroy();
capture.onDestroy();
}
@Override
protected void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
capture.onSaveInstanceState(outState);
}
@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
return barcodeScannerView.onKeyDown(keyCode, event) || super.onKeyDown(keyCode, event);
}
}
问题是，当我尝试使用此类运行扫描程序时，应用程序崩溃，但异常：
java.lang.NullPointerException: Attempt to invoke virtual method 'void com.journeyapps.barcodescanner.camera.CameraInstance.setSurfaceHolder(android.view.SurfaceHolder)' on a null object reference
at com.journeyapps.barcodescanner.CameraPreview.startCameraPreview(CameraPreview.java:472)
at com.journeyapps.barcodescanner.CameraPreview.startPreviewIfReady(CameraPreview.java:320)
at com.journeyapps.barcodescanner.CameraPreview.access$200(CameraPreview.java:48)
at com.journeyapps.barcodescanner.CameraPreview$1.surfaceChanged(CameraPreview.java:130)
at android.view.SurfaceView.updateWindow(SurfaceView.java:618)
at android.view.SurfaceView.setFrame(SurfaceView.java:308)
at android.view.View.layout(View.java:16691)
at com.journeyapps.barcodescanner.CameraPreview.onLayout(CameraPreview.java:337)
at android.view.View.layout(View.java:16695)
at android.view.ViewGroup.layout(ViewGroup.java:5328)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:573)
at android.widget.FrameLayout.onLayout(FrameLayout.java:508)
at android.view.View.layout(View.java:16695)
at android.view.ViewGroup.layout(ViewGroup.java:5328)
at android.widget.RelativeLayout.onLayout(RelativeLayout.java:1077)
at android.view.View.layout(View.java:16695)
at android.view.ViewGroup.layout(ViewGroup.java:5328)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:573)
at android.widget.FrameLayout.onLayout(FrameLayout.java:508)
at android.view.View.layout(View.java:16695)
at android.view.ViewGroup.layout(ViewGroup.java:5328)
at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1702)
at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1556)
at android.widget.LinearLayout.onLayout(LinearLayout.java:1465)
at android.view.View.layout(View.java:16695)
at android.view.ViewGroup.layout(ViewGroup.java:5328)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:573)
at android.widget.FrameLayout.onLayout(FrameLayout.java:508)
at android.view.View.layout(View.java:16695)
at android.view.ViewGroup.layout(ViewGroup.java:5328)
at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1702)
at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1556)
at android.widget.LinearLayout.onLayout(LinearLayout.java:1465)
at android.view.View.layout(View.java:16695)
at android.view.ViewGroup.layout(ViewGroup.java:5328)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:573)
at android.widget.FrameLayout.onLayout(FrameLayout.java:508)
at android.view.View.layout(View.java:16695)
at android.view.ViewGroup.layout(ViewGroup.java:5328)
at android.view.ViewRootImpl.performLayout(ViewRootImpl.java:2319)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:2032)
at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1191)
at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:6642)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:777)
at android.view.Choreographer.doCallbacks(Choreographer.java:590)
at android.view.Choreographer.doFrame(Choreographer.java:560)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:763)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:145)
at android.app.ActivityThread.main(ActivityThread.java:5942)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1400)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1195).*
默认的BarcodeCaptureActivity工作正常，仅在带有工具栏的活动时抛出异常。 有什么问题？