看看https://stackoverflow.com/a/39144104/2914140，我简化了一点:

// In onCreateView():
view.edit_text.run {
    requestFocus()
    post { showKeyboard(this) }
}

fun showKeyboard(view: View) {
    val imm = view.context.getSystemService(
        Context.INPUT_METHOD_SERVICE) as InputMethodManager?
    imm?.showSoftInput(view, InputMethodManager.SHOW_IMPLICIT)
}

它比https://stackoverflow.com/a/11155404/2914140:好

InputMethodManager imm = (InputMethodManager) getSystemService(Context.INPUT_METHOD_SERVICE);
imm.toggleSoftInput(InputMethodManager.SHOW_FORCED, 0);

因为当你按Home键并移动到主屏幕时，键盘会保持打开状态。

如果有人想:

不能从Activity类型对非静态方法getSystemService(String)进行静态引用

尝试向getSystemService调用添加上下文。

So

InputMethodManager imm = 
(InputMethodManager) context.getSystemService(Context.INPUT_METHOD_SERVICE);
imm.toggleSoftInput(InputMethodManager.SHOW_FORCED,0);

只需将这一行添加到manifest文件必要的活动。

android：windowSoftInputMode=“stateVisible”

我的方法使用了Android 11+的新方法，也支持旧版本:

fun Fragment.showKeyboard() {
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.R) {
        ViewCompat.getWindowInsetsController(requireView())?.show(WindowInsetsCompat.Type.ime())
    } else {
        val focusedView = view?.findFocus() ?: view?.apply { requestFocus() }
        val imm = (context?.getSystemService(Context.INPUT_METHOD_SERVICE) as InputMethodManager)
        val isShowSucceeded = imm.showSoftInput(focusedView, InputMethodManager.SHOW_IMPLICIT)
        if(!isShowSucceeded) {
            imm.toggleSoftInputFromWindow(
                view?.windowToken, 0, InputMethodManager.HIDE_IMPLICIT_ONLY)
    }
}

}

让我指出一些额外的信息，解决yuku，因为我发现很难得到这个工作!我如何从我的AlertDialog. builder获得AlertDialog对象?嗯，这是alert.show()执行的结果:

final AlertDialog.Builder alert = new AlertDialog.Builder(getActivity());
final EditText input = new EditText(getActivity());
alert.setView(input);

// do what you need, like setting positive and negative buttons...

final AlertDialog dialog = alert.show();

input.setOnFocusChangeListener(new OnFocusChangeListener() {
   @Override
   public void onFocusChange(View v, boolean hasFocus) {
      if(hasFocus) {
         dialog.getWindow().setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_STATE_ALWAYS_VISIBLE);
      }
   }
});

显示键盘使用情况:

InputMethodManager imm = (InputMethodManager) getSystemService(Context.INPUT_METHOD_SERVICE);
imm.toggleSoftInput(InputMethodManager.SHOW_FORCED,0);

隐藏键盘使用:

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