当我旋转我的Android设备时，应用程序失败

Question

我正在处理一个项目，它给了我一个错误。当我打开列表时，错误显示，而不是旋转设备。如果我尝试选择项目或关闭列表，则会失败。代码如下：

private void showDevicesMenu() {
        if (Utils.isDeviceOnline(getActivity())) {
            if (getFragmentManager().findFragmentByTag("deviceFragment") == null) {
                this.deviceAdapter = new DevicesMenuAdapter<String, Devices>(
                        getActivity(), retainFragment.getDeviceList());
                /*
                 * this.deviceAdapter = new DevicesMenuAdapter(getActivity(),
                 * android.R.layout.simple_list_item_1, getDevicesAlias());
                 */
                this.deviceFragment = new DevicesMenuFragment();
                this.deviceFragment.setListAdapter(deviceAdapter);
                getFragmentManager()
                        .beginTransaction()
                        .replace(R.id.content, deviceFragment, "deviceFragment")
                        .commit();
            } else {
                getFragmentManager().beginTransaction().remove(deviceFragment)
                        .commit();
            }
        } else {
            Toast.makeText(mContext, R.string.no_internet_label,
                    Toast.LENGTH_LONG).show();
        }
    }

错误如下：

03-26 09:29:22.669: E/AndroidRuntime(5692): FATAL EXCEPTION: main
03-26 09:29:22.669: E/AndroidRuntime(5692): java.lang.NullPointerException
03-26 09:29:22.669: E/AndroidRuntime(5692):     at android.app.BackStackRecord.run(BackStackRecord.java:651)
03-26 09:29:22.669: E/AndroidRuntime(5692):     at android.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1455)
03-26 09:29:22.669: E/AndroidRuntime(5692):     at android.app.FragmentManagerImpl$1.run(FragmentManager.java:441)
03-26 09:29:22.669: E/AndroidRuntime(5692):     at android.os.Handler.handleCallback(Handler.java:730)
03-26 09:29:22.669: E/AndroidRuntime(5692):     at android.os.Handler.dispatchMessage(Handler.java:92)
03-26 09:29:22.669: E/AndroidRuntime(5692):     at android.os.Looper.loop(Looper.java:176)
03-26 09:29:22.669: E/AndroidRuntime(5692):     at android.app.ActivityThread.main(ActivityThread.java:5419)
03-26 09:29:22.669: E/AndroidRuntime(5692):     at java.lang.reflect.Method.invokeNative(Native Method)
03-26 09:29:22.669: E/AndroidRuntime(5692):     at java.lang.reflect.Method.invoke(Method.java:525)
03-26 09:29:22.669: E/AndroidRuntime(5692):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1046)
03-26 09:29:22.669: E/AndroidRuntime(5692):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:862)
03-26 09:29:22.669: E/AndroidRuntime(5692):     at dalvik.system.NativeStart.main(Native Method)

我该怎么做？

Answer 1

将configChanges放入AndroidManifest.xml

<activity
   android:name="YourActivity"
   android:configChanges="keyboardHidden|orientation|screenSize"
   >

我希望这段代码可以帮到你。

谢谢。

Answer 2

您只需将此行添加到活动文件

即可

<activity
 android:name="YourActivity"
 android:configChanges="keyboardHidden|orientation|screenSize">
 ........
 .......
</activity>

并将此功能添加到您的Activity类中......您可以在这里做任何事情......

@Override
public void onConfigurationChanged(Configuration newConfig) {
    super.onConfigurationChanged(newConfig);

    // Checks the orientation of the screen
    if (newConfig.orientation == Configuration.ORIENTATION_LANDSCAPE) {
        screen_calculation();

    } else if (newConfig.orientation == Configuration.ORIENTATION_PORTRAIT) {
        screen_calculation();
    }
    // Checks whether a hardware keyboard is available
    if (newConfig.hardKeyboardHidden == Configuration.HARDKEYBOARDHIDDEN_NO) {
    } else if (newConfig.hardKeyboardHidden == Configuration.HARDKEYBOARDHIDDEN_YES) {
    }
}