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

我在这一行得到一个空指针异常:

I get a null pointer exception at this row:

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

这是从以下方法调用的:

This is called from the following method:

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

这是唯一的活动.后退按钮是从片段中按下的.

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焦点视图.

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，它可能是焦点视图.当 EditText 不再聚焦时，getCurrentFocus() 可能返回 null(除非聚焦了其他一些视图).

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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