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"

这些答案中有很多是不必要的复杂；这是Kotlin用户在View类上创建一个整洁的小扩展函数的解决方案。

创建一个基本的Kotlin文件（我已命名为我的KeyboardUtil.kt），并介绍以下内容：

fun View.hideKeyboard() {
  val imm = ContextCompat.getSystemService(context, InputMethodManager::class.java) as InputMethodManager
  imm.hideSoftInputFromWindow(windowToken, 0)
}

然后，您可以在任何视图上调用此命令，以轻松关闭键盘。我使用ViewBinding/DataBinding，它工作得特别好，例如：

fun submitForm() {
  binding.root.hideKeyboard()
  // continue now the keyboard is dismissed
}

一些科特林代码：

从“活动”中隐藏键盘：

(currentFocus ?: View(this))
            .apply { (getSystemService(Activity.INPUT_METHOD_SERVICE) as InputMethodManager)
                        .hideSoftInputFromWindow(windowToken, 0) }

只需在BaseActivity和BaseFragment中为整个应用程序创建通用方法

在onCreate（）中初始化inputMethodManager

inputMethodManager = (InputMethodManager) getSystemService(Context.INPUT_METHOD_SERVICE);

使用此方法隐藏和显示键盘

public void hideKeyBoard(View view) {
     if (view != null) {
         inputMethodManager.hideSoftInputFromWindow(view.getWindowToken(), 0);
      }
 }

public void showKeyboard(View view, boolean isForceToShow) {
      if (isForceToShow)
         inputMethodManager.toggleSoftInput(InputMethodManager.SHOW_FORCED, 0);
      else if (view != null)
           inputMethodManager.showSoftInput(view, 0);
}

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
    }
}

 //In Activity
        View v = this.getCurrentFocus();
        if (v != null) {
            InputMethodManager im = (InputMethodManager)getSystemService(Context.INPUT_METHOD_SERVICE);
            im.hideSoftInputFromWindow(view.getWindowToken(), 0);
        }


//In Fragment
        View v = getActivity().getCurrentFocus();
        if (v != null) {
            InputMethodManager im = (InputMethodManager)getActivity().getSystemService(Context.INPUT_METHOD_SERVICE);
            im.hideSoftInputFromWindow(view.getWindowToken(), 0);
        }
```