与Android 10（API 29）一起工作

val activityView = activity?.window?.decorView?.rootView
activityView?.let {
    val imm = activity?.getSystemService(Context.INPUT_METHOD_SERVICE) as? InputMethodManager
    imm?.hideSoftInputFromWindow(it.windowToken, 0)
}

有时你只需要按回车键来折叠键盘在“编辑文本”框中指定属性

 android:imeOptions="actionDone" 

这将将Enter按钮更改为Done按钮，该按钮将关闭键盘。

这对我所有奇怪的键盘行为都有效

private boolean isKeyboardVisible() {
    Rect r = new Rect();
    //r will be populated with the coordinates of your view that area still visible.
    mRootView.getWindowVisibleDisplayFrame(r);

    int heightDiff = mRootView.getRootView().getHeight() - (r.bottom - r.top);
    return heightDiff > 100; // if more than 100 pixels, its probably a keyboard...
}

protected void showKeyboard() {
    if (isKeyboardVisible())
        return;
    InputMethodManager inputMethodManager = (InputMethodManager) getSystemService(Context.INPUT_METHOD_SERVICE);
    if (getCurrentFocus() == null) {
        inputMethodManager.toggleSoftInput(InputMethodManager.SHOW_FORCED, 0);
    } else {
        View view = getCurrentFocus();
        inputMethodManager.showSoftInput(view, InputMethodManager.SHOW_FORCED);
    }
}

protected void hideKeyboard() {
    if (!isKeyboardVisible())
        return;
    InputMethodManager inputMethodManager = (InputMethodManager) getSystemService(Context.INPUT_METHOD_SERVICE);
    View view = getCurrentFocus();
    if (view == null) {
        if (inputMethodManager.isAcceptingText())
            inputMethodManager.toggleSoftInput(InputMethodManager.HIDE_NOT_ALWAYS, 0);
    } else {
        if (view instanceof EditText)
            ((EditText) view).setText(((EditText) view).getText().toString()); // reset edit text bug on some keyboards bug
        inputMethodManager.hideSoftInputFromInputMethod(view.getWindowToken(), InputMethodManager.HIDE_NOT_ALWAYS);
    }
}

public static void closeInput(final View caller) {  
    caller.postDelayed(new Runnable() {
        @Override
        public void run() {
            InputMethodManager imm = (InputMethodManager) caller.getContext().getSystemService(Context.INPUT_METHOD_SERVICE);
            imm.hideSoftInputFromWindow(caller.getWindowToken(), InputMethodManager.HIDE_NOT_ALWAYS);
        }
    }, 100);
}

此方法通常有效，但有一个条件：不能设置android:windowSoftInputMode=“any_of_themes”

Kotlin中的Wiki答案：

1-在文件中创建顶级函数（例如，包含所有顶级函数的文件）：

fun Activity.hideKeyboard(){
    val imm = this.getSystemService(Activity.INPUT_METHOD_SERVICE) as InputMethodManager
    var view = currentFocus
    if (view == null) { view = View(this) }
    imm.hideSoftInputFromWindow(view.windowToken, 0)
}

2-然后在你需要的任何活动中调用它：

this.hideKeyboard()

在Kotlin

fun hideKeyboard(activity: BaseActivity) {
        val view = activity.currentFocus?: View(activity)
        val imm = activity.getSystemService(Activity.INPUT_METHOD_SERVICE) as InputMethodManager
        imm.hideSoftInputFromWindow(view.windowToken, 0)
    }