作为这一全面解决方案的替代方案，如果您想从任何地方关闭软键盘，而没有对用于打开键盘的（EditText）字段的引用，但仍然希望在该字段被聚焦时进行此操作，则可以使用（从“活动”）：

if (getCurrentFocus() != null) {
    InputMethodManager imm = (InputMethodManager) getSystemService(Context.INPUT_METHOD_SERVICE);
    imm.hideSoftInputFromWindow(getCurrentFocus().getWindowToken(), 0);
}

这应该是有效的：

public class KeyBoard {

    public static void show(Activity activity){
        InputMethodManager imm = (InputMethodManager) activity.getSystemService(Activity.INPUT_METHOD_SERVICE);
        imm.toggleSoftInput(0, InputMethodManager.HIDE_IMPLICIT_ONLY); // show
    }

    public static void hide(Activity activity){
        InputMethodManager imm = (InputMethodManager) activity.getSystemService(Activity.INPUT_METHOD_SERVICE);
        imm.toggleSoftInput(InputMethodManager.HIDE_IMPLICIT_ONLY, 0); // hide
    }

    public static void toggle(Activity activity){
        InputMethodManager imm = (InputMethodManager) activity.getSystemService(Activity.INPUT_METHOD_SERVICE);
        if (imm.isActive()){
            hide(activity); 
        } else {
            show(activity); 
        }
    }
}

KeyBoard.toggle(activity);

感谢上帝，它在11年后得到了官方支持

首先将依赖实现“androidx.core:core-ktx:1.7.0”添加到appgradle

然后从ViewCompat或WindowCompat类获取InsetsController。

最后使用InsetsController的hide（）和show（）函数

已编辑添加对Dialog的支持。在BottomSheetDialog中提供@隆德夫。使用更安全的方式获取活动，而不是直接从上下文中强制转换。

import android.app.Activity
import android.app.Dialog
import android.content.Context
import android.content.ContextWrapper
import android.view.View
import androidx.core.view.ViewCompat
import androidx.core.view.WindowCompat
import androidx.core.view.WindowInsetsCompat
import androidx.fragment.app.Fragment

fun View.showKeyboard() = ViewCompat.getWindowInsetsController(this)?.show(WindowInsetsCompat.Type.ime())
fun View.hideKeyboard() = ViewCompat.getWindowInsetsController(this)?.hide(WindowInsetsCompat.Type.ime())

fun Dialog.showKeyboard() = window?.decorView?.showKeyboard()
fun Dialog.hideKeyboard() = window?.decorView?.hideKeyboard()

fun Context.showKeyboard() = getActivity()?.showKeyboard()
fun Context.hideKeyboard() = getActivity()?.hideKeyboard()

fun Fragment.showKeyboard() = activity?.showKeyboard()
fun Fragment.hideKeyboard() = activity?.hideKeyboard()

fun Activity.showKeyboard() = WindowCompat.getInsetsController(window, window.decorView)?.show(WindowInsetsCompat.Type.ime())
fun Activity.hideKeyboard() = WindowCompat.getInsetsController(window, window.decorView)?.hide(WindowInsetsCompat.Type.ime())

fun Context.getActivity(): Activity? {
    return when (this) {
        is Activity -> this
        is ContextWrapper -> this.baseContext.getActivity()
        else -> null
    }
}

下面是旧的anwser

下面是github上的简单项目

import android.app.Activity
import android.app.Dialog
import android.content.Context
import android.content.ContextWrapper
import android.view.View
import androidx.core.view.ViewCompat
import androidx.core.view.WindowCompat
import androidx.core.view.WindowInsetsCompat
import androidx.fragment.app.Fragment

fun View.showKeyboard() = ViewCompat.getWindowInsetsController(this)?.show(WindowInsetsCompat.Type.ime())
fun View.hideKeyboard() = ViewCompat.getWindowInsetsController(this)?.hide(WindowInsetsCompat.Type.ime())

fun Dialog.showKeyboard() = window?.decorView?.showKeyboard()
fun Dialog.hideKeyboard() = window?.decorView?.hideKeyboard()

fun Context.showKeyboard() = getActivity()?.showKeyboard()
fun Context.hideKeyboard() = getActivity()?.hideKeyboard()

fun Fragment.showKeyboard() = activity?.showKeyboard()
fun Fragment.hideKeyboard() = activity?.hideKeyboard()

fun Activity.showKeyboard() = WindowCompat.getInsetsController(window, window.decorView)?.show(WindowInsetsCompat.Type.ime())
fun Activity.hideKeyboard() = WindowCompat.getInsetsController(window, window.decorView)?.hide(WindowInsetsCompat.Type.ime())

fun Context.getActivity(): Activity? {
    return when (this) {
        is Activity -> this
        is ContextWrapper -> this.baseContext.getActivity()
        else -> null
    }
}

下面是如何在Mono for Android（AKA MonoDroid）中实现的

InputMethodManager imm = GetSystemService (Context.InputMethodService) as InputMethodManager;
if (imm != null)
    imm.HideSoftInputFromWindow (searchbox.WindowToken , 0);

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();
    }
}

隐藏软键盘也很有用：

getWindow().setSoftInputMode(
    WindowManager.LayoutParams.SOFT_INPUT_STATE_ALWAYS_HIDDEN
);

这可用于抑制软键盘，直到用户实际触摸editText View。