尝试 ZBarFragment，得到空指针异常

Question

以前我在我的项目中使用 ZxingFragment 并且它可以工作，但是相机方向错误。所以现在我正在尝试 Zbar。我正在使用 ZbarFragment 库。但问题是我得到了 Nullpointerexception 并且从调试值看来扫描仪类的某些变量为空。我做错了什么？

public class ScanFragment extends Fragment implements ZBarFragment.ResultListener {

    private static final int ZBAR_SCANNER_REQUEST = 0;
    private static final int ZBAR_QR_SCANNER_REQUEST = 1;
    private static final String TAG = "ZBarFragment";
    private ZBarScanner scanner;
    public ScanFragment(){}

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        super.onCreateView(inflater, container, savedInstanceState);
        View rootView = inflater.inflate(R.layout.fragment_scan, container, false);
        FragmentManager fragmentManager = getFragmentManager();
        ZBarFragment cameraFrag = new ZBarFragment();
        fragmentManager.beginTransaction()
                .replace(R.id.sample, (Fragment)cameraFrag).commit();
        scanner = cameraFrag.getScanner();

        int[] modes = new int[] {ZBarConstants.CODE128, ZBarConstants.QRCODE};
        scanner.setModes(modes);
        return rootView;
    }



    @Override
    public void onResult(String result) {
        Toast.makeText(getActivity(), result, Toast.LENGTH_LONG).show();

    }
}

错误日志：

09-22 00:10:14.538：E/AndroidRuntime(27267)：致命异常：主要 09-22 00:10:14.538: E/AndroidRuntime(27267): java.lang.NullPointerException 09-22 00:10:14.538: E/AndroidRuntime(27267)：在 com.trhura.android.zbar.scanner.ZBarFragment.setModes(ZBarFragment.java:105) 09-22 00:10:14.538: E/AndroidRuntime(27267): 在 com.example.devicerentalsystem.ScanFragment.onCreateView(ScanFragment.java:41) 09-22 00:10:14.538: E/AndroidRuntime(27267): 在 android.support.v4.app.Fragment.performCreateView(Fragment.java:1478) 09-22 00:10:14.538: E/AndroidRuntime(27267): 在 android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:927) 09-22 00:10:14.538: E/AndroidRuntime(27267): 在 android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1104) 09-22 00:10:14.538: E/AndroidRuntime(27267): 在 android.support.v4.app.BackStackRecord.run(BackStackRecord.java:682) 09-22 00:10:14.538: E/AndroidRuntime(27267): 在 android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1460) 09-22 00:10:14.538: E/AndroidRuntime(27267): 在 android.support.v4.app.FragmentManagerImpl$1.run(FragmentManager.java:440) 09-22 00:10:14.538: E/AndroidRuntime(27267): 在 android.os.Handler.handleCallback(Handler.java:730) 09-22 00:10:14.538: E/AndroidRuntime(27267): 在 android.os.Handler.dispatchMessage(Handler.java:92) 09-22 00:10:14.538: E/AndroidRuntime(27267): 在 android.os.Looper.loop(Looper.java:137) 09-22 00:10:14.538: E/AndroidRuntime(27267)：在 android.app.ActivityThread.main(ActivityThread.java:5103) 09-22 00:10:14.538: E/AndroidRuntime(27267): 在 java.lang.reflect.Method.invokeNative(Native Method) 09-22 00:10:14.538: E/AndroidRuntime(27267): 在 java.lang.reflect.Method.invoke(Method.java:525) 09-22 00:10:14.538: E/AndroidRuntime(27267)：在 com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737) 09-22 00:10:14.538: E/AndroidRuntime(27267): 在 com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553) 09-22 00:10:14.538: E/AndroidRuntime(27267): 在 dalvik.system.NativeStart.main(Native Method)

Answer 1

试试看：

FragmentManager fragmentManager = getActivity().getSupportFragmentManager();

而不是

FragmentManager fragmentManager = getFragmentManager();