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);

protected void hideSoftKeyboard(EditText input) {
    InputMethodManager imm = (InputMethodManager) getSystemService(Context.INPUT_METHOD_SERVICE);
    imm.hideSoftInputFromWindow(input.getWindowToken(), 0);    
}

以下是使用Kotlin隐藏软键盘的最简单方法：

//hides soft keyboard anything else is tapped( screen, menu bar, buttons, etc. )
override fun dispatchTouchEvent( ev: MotionEvent? ): Boolean {
    if ( currentFocus != null ) {
        val imm = getSystemService( Context.INPUT_METHOD_SERVICE ) as InputMethodManager
        imm.hideSoftInputFromWindow( currentFocus!!.windowToken, 0 )
    }
    return super.dispatchTouchEvent( ev )
}

如果要使用Java代码隐藏键盘，请使用以下命令：

  InputMethodManager imm = (InputMethodManager)this.getSystemService(Context.INPUT_METHOD_SERVICE);
  imm.hideSoftInputFromWindow(fEmail.getWindowToken(), 0);

或者，如果您希望始终隐藏键盘，请在AndroidManifest中使用此选项：

 <activity
 android:name=".activities.MyActivity"
 android:configChanges="keyboardHidden"  />

如果有人感兴趣的话，我已经为Kotlin写了一个小扩展，但没有太多测试：

fun Fragment.hideKeyboard(context: Context = App.instance) {
    val windowToken = view?.rootView?.windowToken
    windowToken?.let {
        val imm = context.getSystemService(Activity.INPUT_METHOD_SERVICE) as InputMethodManager
        imm.hideSoftInputFromWindow(windowToken, 0)
    }
}

App.instance是存储在Application中的静态“this”Application对象

更新：在某些情况下，windowToken为空。我增加了使用反射来检测键盘是否关闭的额外关闭方式

/**
 * If no window token is found, keyboard is checked using reflection to know if keyboard visibility toggle is needed
 *
 * @param useReflection - whether to use reflection in case of no window token or not
 */
fun Fragment.hideKeyboard(context: Context = MainApp.instance, useReflection: Boolean = true) {
    val windowToken = view?.rootView?.windowToken
    val imm = context.getSystemService(Context.INPUT_METHOD_SERVICE) as InputMethodManager
    windowToken?.let {
        imm.hideSoftInputFromWindow(windowToken, 0)
    } ?: run {
        if (useReflection) {
            try {
                if (getKeyboardHeight(imm) > 0) {
                    imm.toggleSoftInput(0, InputMethodManager.HIDE_NOT_ALWAYS)
                }
            } catch (exception: Exception) {
                Timber.e(exception)
            }
        }
    }
}

fun getKeyboardHeight(imm: InputMethodManager): Int = InputMethodManager::class.java.getMethod("getInputMethodWindowVisibleHeight").invoke(imm) as Int

更新：我不知道为什么这个解决方案不再有效（我刚刚在Android 23上测试过）。请改用Saurabh Pareek的溶液。这里是：

InputMethodManager imm = (InputMethodManager) getSystemService(Activity.INPUT_METHOD_SERVICE);
//Hide:
imm.toggleSoftInput(InputMethodManager.HIDE_IMPLICIT_ONLY, 0);
//Show
imm.toggleSoftInput(InputMethodManager.SHOW_IMPLICIT, 0);

旧答案：

//Show soft-keyboard:
getWindow().setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_STATE_ALWAYS_VISIBLE);
//hide keyboard :
 getWindow().setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_STATE_ALWAYS_HIDDEN);