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。

您可以在AlertDialog的EditText上创建一个焦点侦听器，然后获取AlertDialog的窗口。从那里你可以通过调用setSoftInputMode来显示软键盘。

final AlertDialog dialog = ...;

editText.setOnFocusChangeListener(new View.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); 

要显示键盘，对我来说，我必须执行以下操作

Android文本字段:设置焦点+软输入编程

基本上解决方案如下

@Override
public void onResume() {
    super.onResume();
    //passwordInput.requestFocus(); <-- that doesn't work
    passwordInput.postDelayed(new ShowKeyboard(), 325); //250 sometimes doesn't run if returning from LockScreen
}

ShowKeyboard在哪里

private class ShowKeyboard implements Runnable {
    @Override
    public void run() {
        passwordInput.setFocusableInTouchMode(true);
        //passwordInput.requestFocusFromTouch(); //this gives touch event to launcher in background -_-
        passwordInput.requestFocus();
        getActivity().getWindow().setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_STATE_ALWAYS_VISIBLE);
        ((InputMethodManager) getActivity().getSystemService(Context.INPUT_METHOD_SERVICE)).showSoftInput(passwordInput, 0);
    }
}

在成功输入之后，我还确保隐藏了键盘

getActivity().getWindow().setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_STATE_HIDDEN);
((InputMethodManager) getActivity().getSystemService(Context.INPUT_METHOD_SERVICE))
                    .hideSoftInputFromWindow(getView().getWindowToken(), 0);

我们可以在对话显示时默认打开键盘

dialog.getWindow().clearFlags(WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE | WindowManager.LayoutParams.FLAG_ALT_FOCUSABLE_IM)
dialog.getWindow().setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_STATE_ALWAYS_VISIBLE)

我知道这个问题很老了，因为我认为使用扩展函数是一种更漂亮的方式来显示编辑文本的键盘

下面是我用来显示编辑文本键盘的方法。

芬兰湾的科特林代码: 只需要调用edittext.showKeyboard()

fun EditText.showKeyboard() {
  post {
    requestFocus()
    val imm = context.getSystemService(Context.INPUT_METHOD_SERVICE) as InputMethodManager
    imm.showSoftInput(this, InputMethodManager.SHOW_IMPLICIT)
  }
}

Java代码:

public static void showKeyboard(EditText editText) {
    editText.post(new Runnable() {
      @Override
      public void run() {
        editText.requestFocus();
        InputMethodManager imm = (InputMethodManager) editText.getContext()
            .getSystemService(Context.INPUT_METHOD_SERVICE);
        imm.showSoftInput(editText, InputMethodManager.SHOW_IMPLICIT);
      }
    });
  }