0
我是Android新手。我想知道，爲什麼當我點擊/按回到我的模擬器其總是不幸cameraActivity已停止 這是我CameraTestActivity發佈後調用方法（）錯誤
public class CameraTestActivity extends Activity
{
private Camera mCamera;
private CameraPreview mPreview;
private Handler autoFocusHandler;
TextView scanText;
Button scanButton, btn_next;
ImageScanner scanner;
private boolean barcodeScanned = false;
private boolean previewing = true;
static {
System.loadLibrary("iconv");
}
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);
autoFocusHandler = new Handler();
mCamera = getCameraInstance();
/* Instance barcode scanner */
scanner = new ImageScanner();
scanner.setConfig(0, Config.X_DENSITY, 3);
scanner.setConfig(0, Config.Y_DENSITY, 3);
mPreview = new CameraPreview(this, mCamera, previewCb, autoFocusCB);
FrameLayout preview = (FrameLayout)findViewById(R.id.cameraPreview);
preview.addView(mPreview);
scanText = (TextView)findViewById(R.id.scanText);
btn_next = (Button)findViewById(R.id.button1);
btn_next.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
Intent intent = new Intent (CameraTestActivity.this,
SecondActivity.class);
startActivity(intent);
}
});
scanButton = (Button)findViewById(R.id.ScanButton);
scanButton.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
if (barcodeScanned) {
barcodeScanned = false;
scanText.setText("Scanning...");
mCamera.setPreviewCallback(previewCb);
mCamera.startPreview();
previewing = true;
mCamera.autoFocus(autoFocusCB);
}
}
});
}
public void onPause() {
super.onPause();
releaseCamera();
}
/** A safe way to get an instance of the Camera object. */
public static Camera getCameraInstance(){
Camera c = null;
try {
c = Camera.open();
} catch (Exception e){
}
return c;
}
private void releaseCamera() {
if (mCamera != null) {
previewing = false;
mCamera.setPreviewCallback(null);
mCamera.release();
mCamera = null;
}
}
private Runnable doAutoFocus = new Runnable() {
public void run() {
if (previewing)
mCamera.autoFocus(autoFocusCB);
}
};
PreviewCallback previewCb = new PreviewCallback() {
public void onPreviewFrame(byte[] data, Camera camera) {
Camera.Parameters parameters = camera.getParameters();
Size size = parameters.getPreviewSize();
Image barcode = new Image(size.width, size.height, "Y800");
barcode.setData(data);
int result = scanner.scanImage(barcode);
if (result != 0) {
previewing = false;
mCamera.setPreviewCallback(null);
mCamera.stopPreview();
SymbolSet syms = scanner.getResults();
for (Symbol sym : syms) {
scanText.setText("barcode result " + sym.getData());
barcodeScanned = true;
}
}
}
};
// Mimic continuous auto-focusing
AutoFocusCallback autoFocusCB = new AutoFocusCallback() {
public void onAutoFocus(boolean success, Camera camera) {
autoFocusHandler.postDelayed(doAutoFocus, 1000);
}
};
}
有一個在我的第二個活動無功能。但每當我按回到我的設備與CameraTestActivity找回它說的方法釋放後稱爲（） 這是我的logcat錯誤：
08-02 15:01:56.620: E/AndroidRuntime(7772): java.lang.RuntimeException: Method called
after release()
08-02 15:01:56.620: E/AndroidRuntime(7772): at
android.hardware.Camera.setPreviewDisplay(Native Method)
08-02 15:01:56.620: E/AndroidRuntime(7772): at
android.hardware.Camera.setPreviewDisplay(Camera.java:407)
08-02 15:01:56.620: E/AndroidRuntime(7772): at
net.sourceforge.zbar.android.CameraTest.CameraPreview.surfaceCreated(CameraPreview.
java:69)
08-02 15:01:56.620: E/AndroidRuntime(7772): at
android.view.SurfaceView.updateWindow(SurfaceView.java:533)
08-02 15:01:56.620: E/AndroidRuntime(7772): at
android.view.SurfaceView.onWindowVisibilityChanged(SurfaceView.java:226)
08-02 15:01:56.620: E/AndroidRuntime(7772): at
android.view.View.dispatchWindowVisibilityChanged(View.java:5844)
08-02 15:01:56.620: E/AndroidRuntime(7772): at
android.view.ViewGroup.dispatchWindowVisibilityChanged(ViewGroup.java:945)
08-02 15:01:56.620: E/AndroidRuntime(7772): at
android.view.ViewGroup.dispatchWindowVisibilityChanged(ViewGroup.java:945)
08-02 15:01:56.620: E/AndroidRuntime(7772): at
android.view.ViewGroup.dispatchWindowVisibilityChanged(ViewGroup.java:945)
08-02 15:01:56.620: E/AndroidRuntime(7772): at
android.view.ViewGroup.dispatchWindowVisibilityChanged(ViewGroup.java:945)
08-02 15:01:56.620: E/AndroidRuntime(7772): at
android.view.ViewGroup.dispatchWindowVisibilityChanged(ViewGroup.java:945)
08-02 15:01:56.620: E/AndroidRuntime(7772): at
android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:965)
08-02 15:01:56.620: E/AndroidRuntime(7772): at
android.view.ViewRootImpl.handleMessage(ViewRootImpl.java:2442)
08-02 15:01:56.620: E/AndroidRuntime(7772): at
android.os.Handler.dispatchMessage(Handler.java:99)
08-02 15:01:56.620: E/AndroidRuntime(7772): at
android.os.Looper.loop(Looper.java:137)
08-02 15:01:56.620: E/AndroidRuntime(7772): at
android.app.ActivityThread.main(ActivityThread.java:4424)
08-02 15:01:56.620: E/AndroidRuntime(7772): at
java.lang.reflect.Method.invokeNative(Native Method)
08-02 15:01:56.620: E/AndroidRuntime(7772): at
java.lang.reflect.Method.invoke(Method.java:511)
08-02 15:01:56.620: E/AndroidRuntime(7772): at
com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
08-02 15:01:56.620: E/AndroidRuntime(7772): at
com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
08-02 15:01:56.620: E/AndroidRuntime(7772): at
dalvik.system.NativeStart.main(Native Method)
可能有人幫我解決這一個。
不，但在我的Camera Preview類中有surfaceCreated方法，但根據您的崩潰日誌從未調用 – Drx
，CameraPreview被調用。在surfaceCreated處設置斷點並在按下後退按鈕時調試您的應用程序 – yushulx