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()

通过创建一个扩展来隐藏Kotlin中的软键盘，您可以全局使用该扩展。为此，需要创建一个Singleton类。

object Extensions {
    
      fun View.hideKeyboard() {
            val inputMethodManager =                                                 
            context.getSystemService(AppCompatActivity.INPUT_METHOD_SERVICE)           
            as InputMethodManager
            inputMethodManager.hideSoftInputFromWindow(windowToken, 0)
        }
    }

在需要隐藏键盘的片段类的活动中，可以使用mainlayout id调用此函数，如下所示

//constraintEditLayout is my main view layout, if you are using other layout like relative or linear layouts you can call with that layout id
constraintEditLayout.hideKeyboard()

可以为任何视图创建Extension函数

fun View.hideKeyboard() = this.let {
    val imm = context.getSystemService(Context.INPUT_METHOD_SERVICE) as InputMethodManager
    imm.hideSoftInputFromWindow(windowToken, 0)
}

与活动一起使用的示例

window.decorView.hideKeyboard();

与视图一起使用的示例

etUsername.hideKeyboard();

快乐编码。。。

碎片形式的科特林溶液：

fun hideSoftKeyboard() {
        val view = activity?.currentFocus
        view?.let { v ->
            val imm =
                activity?.getSystemService(Context.INPUT_METHOD_SERVICE) as InputMethodManager // or context
            imm.hideSoftInputFromWindow(v.windowToken, 0)
        }
}

检查您的清单是否没有与活动关联的此参数：

android:windowSoftInputMode="stateAlwaysHidden"

事实上，Android权威机构总是在提供新的更新，但他们并没有处理所有Android开发人员在开发过程中面临的旧缺点。默认情况下，这应该由Android权威机构处理，在更改EditText的焦点时，应该隐藏/显示软输入键盘选项。但很抱歉，他们没有管理。好的，留下来。

以下是在“活动”或“片段”中显示/隐藏/切换键盘选项的解决方案。

显示视图的键盘：

/**
 * open soft keyboard.
 *
 * @param context
 * @param view
 */
public static void showKeyBoard(Context context, View view) {
    try {
        InputMethodManager keyboard = (InputMethodManager) context.getSystemService(Context.INPUT_METHOD_SERVICE);
        keyboard.showSoftInput(view, 0);
    } catch (Exception e) {
        e.printStackTrace();
    }
}

显示带有活动上下文的键盘：

/**
 * open soft keyboard.
 *
 * @param mActivity context
 */
public static void showKeyBoard(Activity mActivity) {
    try {
        View view = mActivity.getCurrentFocus();
        if (view != null) {
            InputMethodManager keyboard = (InputMethodManager) mActivity.getSystemService(Context.INPUT_METHOD_SERVICE);
            keyboard.showSoftInputFromInputMethod(view.getWindowToken(), InputMethodManager.SHOW_FORCED);
        }
    } catch (Exception e) {
        e.printStackTrace();
    }
}

显示带有片段上下文的键盘：

/**
 * open soft keyboard.
 *
 * @param mFragment context
 */
public static void showKeyBoard(Fragment mFragment) {
    try {
        if (mFragment == null || mFragment.getActivity() == null) {
            return;
        }
        View view = mFragment.getActivity().getCurrentFocus();
        if (view != null) {
            InputMethodManager keyboard = (InputMethodManager) mFragment.getActivity().getSystemService(Context.INPUT_METHOD_SERVICE);
            keyboard.showSoftInputFromInputMethod(view.getWindowToken(), InputMethodManager.SHOW_FORCED);
        }
    } catch (Exception e) {
        e.printStackTrace();
    }
}

隐藏视图的键盘：

/**
 * close soft keyboard.
 *
 * @param context
 * @param view
 */
public static void hideKeyBoard(Context context, View view) {
    try {
        InputMethodManager keyboard = (InputMethodManager) context.getSystemService(Context.INPUT_METHOD_SERVICE);
        keyboard.hideSoftInputFromWindow(view.getWindowToken(), 0);
    } catch (Exception e) {
        e.printStackTrace();
    }
}

使用“活动”上下文隐藏键盘：

/**
 * close opened soft keyboard.
 *
 * @param mActivity context
 */
public static void hideSoftKeyboard(Activity mActivity) {
    try {
        View view = mActivity.getCurrentFocus();
        if (view != null) {
            InputMethodManager inputManager = (InputMethodManager) mActivity.getSystemService(Context.INPUT_METHOD_SERVICE);
            inputManager.hideSoftInputFromWindow(view.getWindowToken(), 0);
        }
    } catch (Exception e) {
        e.printStackTrace();
    }
}

使用片段上下文隐藏键盘：

/**
 * close opened soft keyboard.
 *
 * @param mFragment context
 */
public static void hideSoftKeyboard(Fragment mFragment) {
    try {
        if (mFragment == null || mFragment.getActivity() == null) {
            return;
        }
        View view = mFragment.getActivity().getCurrentFocus();
        if (view != null) {
            InputMethodManager inputManager = (InputMethodManager) mFragment.getActivity().getSystemService(Context.INPUT_METHOD_SERVICE);
            inputManager.hideSoftInputFromWindow(view.getWindowToken(), 0);
        }
    } catch (Exception e) {
        e.printStackTrace();
    }
}

切换键盘：

/**
 * toggle soft keyboard.
 *
 * @param context
 */
public static void toggleSoftKeyboard(Context context) {
    try {
        InputMethodManager imm = (InputMethodManager) context.getSystemService(Activity.INPUT_METHOD_SERVICE);
        imm.toggleSoftInput(InputMethodManager.HIDE_IMPLICIT_ONLY, 0);
    } catch (Exception e) {
        e.printStackTrace();
    }
}

您也可以使用此代码段在Kotlin中隐藏键盘。

 fun hideKeyboard(activity: Activity?) {
    val inputManager: InputMethodManager? = 
    activity?.getSystemService(Context.INPUT_METHOD_SERVICE) as? 
    InputMethodManager
    // check if no view has focus:
    val v = activity?.currentFocus ?: return
    inputManager?.hideSoftInputFromWindow(v.windowToken, 0)
 }