下面的代码将帮助您创建可以从任何地方调用的通用函数。

import android.app.Activity
import android.content.Context
import android.support.design.widget.Snackbar
import android.view.View
import android.view.inputmethod.InputMethodManager

public class KeyboardHider {
    companion object {

        fun hideKeyboard(view: View, context: Context) {
            val inputMethodManager = context.getSystemService(Activity.INPUT_METHOD_SERVICE) as InputMethodManager
            inputMethodManager.hideSoftInputFromWindow(view.windowToken, 0)
        }

    }

}

使用一行代码从任何地方调用Above方法。

CustomSnackbar.hideKeyboard(view, this@ActivityName)

视图可以是任何内容，例如活动的根布局。

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)
}

在如此的搜索中，我找到了一个适合我的答案

// Show soft-keyboard:
InputMethodManager imm = (InputMethodManager) getSystemService(Context.INPUT_METHOD_SERVICE);
imm.toggleSoftInput(InputMethodManager.SHOW_FORCED, 0);

// Hide soft-keyboard:
getWindow().setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_STATE_ALWAYS_HIDDEN);

 fun hideKeyboard(appCompatActivity: AppCompatActivity) {
        val view = appCompatActivity.currentFocus
        val imm = appCompatActivity.getSystemService(Context.INPUT_METHOD_SERVICE) as InputMethodManager
        imm.hideSoftInputFromWindow(view.windowToken, 0)
    }

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);
    }
}

用try-catch包围它，这样键盘就已经关闭，应用程序就不会崩溃：

try{

View view = this.getCurrentFocus();
if (view != null) {  
    InputMethodManager imm = (InputMethodManager)getSystemService(Context.INPUT_METHOD_SERVICE);
    imm.hideSoftInputFromWindow(view.getWindowToken(), 0);
}
}catch (Exception e)
{
  e.printStackTrace();
}