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试试这个

 private fun hideKeyboard(){
    val imm = activity!!.getSystemService(INPUT_METHOD_SERVICE) as InputMethodManager
    imm.hideSoftInputFromWindow(activity!!.currentFocus!!.windowToken, 0)
}

在Java中尝试

 private void hideKeyboard(){
  InputMethodManager imm =(InputMethodManager)getSystemService(INPUT_METHOD_SERVICE);
  imm.hideSoftInputFromWindow(getCurrentFocus().getWindowToken(), 0);
}

您可以使用InputMethodManager强制Android隐藏虚拟键盘，调用hideSoftInputFromWindow，传入包含焦点视图的窗口的标记。

// Check if no view has focus:
View view = this.getCurrentFocus();
if (view != null) {  
    InputMethodManager imm = (InputMethodManager)getSystemService(Context.INPUT_METHOD_SERVICE);
    imm.hideSoftInputFromWindow(view.getWindowToken(), 0);
}

这将在所有情况下强制隐藏键盘。在某些情况下，您需要将InputMethodManager.HIDE_IMPLICIT_ONLY作为第二个参数传递，以确保仅在用户未显式强制显示键盘时（通过按住菜单）隐藏键盘。

注意：如果您想在Kotlin中执行此操作，请使用：上下文getSystemService（Context.INPUT_METHOD_SERVICE）作为InputMethodManager

Kotlin语法

// Only runs if there is a view that is currently focused
this.currentFocus?.let { view ->
    val imm = getSystemService(Context.INPUT_METHOD_SERVICE) as? InputMethodManager
    imm?.hideSoftInputFromWindow(view.windowToken, 0)
}

这对我有用：

 @Override
 public boolean dispatchTouchEvent(MotionEvent event) {
View v = getCurrentFocus();
boolean ret = super.dispatchTouchEvent(event);

if (v instanceof EditText) {
    View w = getCurrentFocus();
    int scrcoords[] = new int[2];
    w.getLocationOnScreen(scrcoords);
    float x = event.getRawX() + w.getLeft() - scrcoords[0];
    float y = event.getRawY() + w.getTop() - scrcoords[1];

    Log.d("Activity",
            "Touch event " + event.getRawX() + "," + event.getRawY()
                    + " " + x + "," + y + " rect " + w.getLeft() + ","
                    + w.getTop() + "," + w.getRight() + ","
                    + w.getBottom() + " coords " + scrcoords[0] + ","
                    + scrcoords[1]);
    if (event.getAction() == MotionEvent.ACTION_UP
            && (x < w.getLeft() || x >= w.getRight() || y < w.getTop() || y > w
                    .getBottom())) {

        InputMethodManager imm = (InputMethodManager) getSystemService(Context.INPUT_METHOD_SERVICE);
        imm.hideSoftInputFromWindow(getWindow().getCurrentFocus()
                .getWindowToken(), 0);
    }
}
return ret;
}

当您想手动隐藏键盘时，单击按钮：

/**
 * Hides the already popped up keyboard from the screen.
 *
 */
public void hideKeyboard() {
    try {
        // use application level context to avoid unnecessary leaks.
        InputMethodManager inputManager = (InputMethodManager) getApplicationContext().getSystemService(Context.INPUT_METHOD_SERVICE);
        assert inputManager != null;
        inputManager.hideSoftInputFromWindow(getCurrentFocus().getWindowToken(), InputMethodManager.HIDE_NOT_ALWAYS);
    } catch (Exception e) {
        e.printStackTrace();
    }
}

当您想在屏幕上除编辑文本以外的任何地方隐藏键盘时在活动中重写此方法：

@Override
public boolean dispatchTouchEvent(MotionEvent ev) {
    View view = getCurrentFocus();
    if (view != null && (ev.getAction() == MotionEvent.ACTION_UP || ev.getAction() == MotionEvent.ACTION_MOVE) && view instanceof EditText && !view.getClass().getName().startsWith("android.webkit.")) {
        int scrcoords[] = new int[2];
        view.getLocationOnScreen(scrcoords);
        float x = ev.getRawX() + view.getLeft() - scrcoords[0];
        float y = ev.getRawY() + view.getTop() - scrcoords[1];
        if (x < view.getLeft() || x > view.getRight() || y < view.getTop() || y > view.getBottom())
            ((InputMethodManager)this.getSystemService(Context.INPUT_METHOD_SERVICE)).hideSoftInputFromWindow((this.getWindow().getDecorView().getApplicationWindowToken()), 0);
    }
    return super.dispatchTouchEvent(ev);
}

如果你使用Kotlin开发你的应用程序，这真的很容易做到。

添加此扩展功能：

对于活动：

fun Activity.hideKeyboard() {
    val inputManager = getSystemService(Context.INPUT_METHOD_SERVICE) as InputMethodManager
    val view = currentFocus
    if (view != null) {
        inputManager.hideSoftInputFromWindow(view.windowToken, InputMethodManager.HIDE_NOT_ALWAYS)
    }
}

对于片段：

fun Fragment.hideKeyboard() {
    activity?.let {
        val inputManager = it.getSystemService(Context.INPUT_METHOD_SERVICE) as InputMethodManager
        val view = it.currentFocus
        if (view != null) {
            inputManager.hideSoftInputFromWindow(view.windowToken, InputMethodManager.HIDE_NOT_ALWAYS)
        }
    }
}

现在，您可以简单地调用片段或活动：

 hideKeyboard()