hideSoftInputFromWindow出现空指针错误 [英] Null pointer error with hideSoftInputFromWindow

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本文介绍了hideSoftInputFromWindow出现空指针错误的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！

问题描述

此行出现空指针异常:

public void hideKeyboard(){ 
InputMethodManager inputManager = (InputMethodManager)            
            this.getSystemService(Context.INPUT_METHOD_SERVICE);    
inputManager.hideSoftInputFromWindow(this.getCurrentFocus().getWindowToken(),      
            InputMethodManager.HIDE_NOT_ALWAYS);
}

这是通过以下方法调用的:

This is called from the following method:

@Override
public void onBackPressed() {
    super.onBackPressed();
    hideKeyboard();
}

这是唯一的活动.从片段按下后退按钮.

This is in the only activity. The back button is pressed from a fragment.

堆栈:

09-28 19:14:40.301: E/InputEventSender(30324): Exception dispatching finished signal.
09-28 19:14:40.301: E/MessageQueue-JNI(30324): Exception in MessageQueue callback: handleReceiveCallback
09-28 19:14:40.325: E/MessageQueue-JNI(30324): java.lang.NullPointerException
09-28 19:14:40.325: E/MessageQueue-JNI(30324):  at com.example.ecohelp.MainActivity.hideKeyboard(MainActivity.java:75)
09-28 19:14:40.325: E/MessageQueue-JNI(30324):  at com.example.ecohelp.MainActivity.onBackPressed(MainActivity.java:31)
09-28 19:14:40.325: E/MessageQueue-JNI(30324):  at android.app.Activity.onKeyUp(Activity.java:2159)
09-28 19:14:40.325: E/MessageQueue-JNI(30324):  at android.view.KeyEvent.dispatch(KeyEvent.java:2647)
09-28 19:14:40.325: E/MessageQueue-JNI(30324):  at android.app.Activity.dispatchKeyEvent(Activity.java:2389)
09-28 19:14:40.325: E/MessageQueue-JNI(30324):  at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchKeyEvent(PhoneWindow.java:1860)
09-28 19:14:40.325: E/MessageQueue-JNI(30324):  at android.view.ViewRootImpl$ViewPostImeInputStage.processKeyEvent(ViewRootImpl.java:3791)
09-28 19:14:40.325: E/MessageQueue-JNI(30324):  at android.view.ViewRootImpl$ViewPostImeInputStage.onProcess(ViewRootImpl.java:3774)
09-28 19:14:40.325: E/MessageQueue-JNI(30324):  at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3379)
09-28 19:14:40.325: E/MessageQueue-JNI(30324):  at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:3429)
09-28 19:14:40.325: E/MessageQueue-JNI(30324):  at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:3398)
09-28 19:14:40.325: E/MessageQueue-JNI(30324):  at android.view.ViewRootImpl$AsyncInputStage.forward(ViewRootImpl.java:3483)
09-28 19:14:40.325: E/MessageQueue-JNI(30324):  at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:3406)
09-28 19:14:40.325: E/MessageQueue-JNI(30324):  at android.view.ViewRootImpl$AsyncInputStage.apply(ViewRootImpl.java:3540)
09-28 19:14:40.325: E/MessageQueue-JNI(30324):  at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3379)
09-28 19:14:40.325: E/MessageQueue-JNI(30324):  at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:3429)
09-28 19:14:40.325: E/MessageQueue-JNI(30324):  at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:3398)
09-28 19:14:40.325: E/MessageQueue-JNI(30324):  at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:3406)
09-28 19:14:40.325: E/MessageQueue-JNI(30324):  at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3379)
09-28 19:14:40.325: E/MessageQueue-JNI(30324):  at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:3429)
09-28 19:14:40.325: E/MessageQueue-JNI(30324):  at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:3398)
09-28 19:14:40.325: E/MessageQueue-JNI(30324):  at android.view.ViewRootImpl$AsyncInputStage.forward(ViewRootImpl.java:3516)
09-28 19:14:40.325: E/MessageQueue-JNI(30324):  at android.view.ViewRootImpl$ImeInputStage.onFinishedInputEvent(ViewRootImpl.java:3666)
09-28 19:14:40.325: E/MessageQueue-JNI(30324):  at android.view.inputmethod.InputMethodManager$PendingEvent.run(InputMethodManager.java:1982)
09-28 19:14:40.325: E/MessageQueue-JNI(30324):  at android.view.inputmethod.InputMethodManager.invokeFinishedInputEventCallback(InputMethodManager.java:1698)
09-28 19:14:40.325: E/MessageQueue-JNI(30324):  at android.view.inputmethod.InputMethodManager.finishedInputEvent(InputMethodManager.java:1689)
09-28 19:14:40.325: E/MessageQueue-JNI(30324):  at android.view.inputmethod.InputMethodManager$ImeInputEventSender.onInputEventFinished(InputMethodManager.java:1959)
09-28 19:14:40.325: E/MessageQueue-JNI(30324):  at android.view.InputEventSender.dispatchInputEventFinished(InputEventSender.java:141)
09-28 19:14:40.325: E/MessageQueue-JNI(30324):  at android.os.MessageQueue.nativePollOnce(Native Method)
09-28 19:14:40.325: E/MessageQueue-JNI(30324):  at android.os.MessageQueue.next(MessageQueue.java:132)
09-28 19:14:40.325: E/MessageQueue-JNI(30324):  at android.os.Looper.loop(Looper.java:124)
09-28 19:14:40.325: E/MessageQueue-JNI(30324):  at android.app.ActivityThread.main(ActivityThread.java:5103)
09-28 19:14:40.325: E/MessageQueue-JNI(30324):  at java.lang.reflect.Method.invokeNative(Native Method)
09-28 19:14:40.325: E/MessageQueue-JNI(30324):  at java.lang.reflect.Method.invoke(Method.java:525)
09-28 19:14:40.325: E/MessageQueue-JNI(30324):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
09-28 19:14:40.325: E/MessageQueue-JNI(30324):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
09-28 19:14:40.325: E/MessageQueue-JNI(30324):  at dalvik.system.NativeStart.main(Native Method)

推荐答案

我只需要在隐藏键盘之前检查是否有聚焦视图即可.

I just need to check if there is a focused view before hiding the keyboard.

例如，如果您的活动或片段中有EditText，则它可能是焦点视图.当EditText不再聚焦时，getCurrentFocus()可能返回null(除非其他视图未聚焦).

For example, if you have an EditText in your activity or fragment, it'll probably be the focused view. When the EditText isn't focused anymore, getCurrentFocus() may return null (unless some other view is focused).

void hideKeyboard() {
    InputMethodManager inputManager = (InputMethodManager) getActivity().getSystemService(
            Context.INPUT_METHOD_SERVICE);
    View focusedView = getActivity().getCurrentFocus();
    /*
     * If no view is focused, an NPE will be thrown
     * 
     * Maxim Dmitriev
     */
    if (focusedView != null) {
        inputManager.hideSoftInputFromWindow(focusedView.getWindowToken(),
                InputMethodManager.HIDE_NOT_ALWAYS);
    }
}

这篇关于hideSoftInputFromWindow出现空指针错误的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！

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