我有同样的问题，并解决了它与以下代码。我不确定它在有硬件键盘的手机上会有什么表现。

// TextEdit
final EditText textEdit = new EditText(this);

// Builder
AlertDialog.Builder alert = new AlertDialog.Builder(this);
alert.setTitle("Enter text");
alert.setView(textEdit);

alert.setPositiveButton("Ok", new DialogInterface.OnClickListener() {
    @Override
    public void onClick(DialogInterface dialog, int which) {
        String text = textEdit.getText().toString();
        finish();
    }
});

alert.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
    @Override
    public void onClick(DialogInterface dialog, int which) {
        finish();
    }
});

// Dialog
AlertDialog dialog = alert.create();
dialog.setOnShowListener(new OnShowListener() {

    @Override
    public void onShow(DialogInterface dialog) {
        InputMethodManager imm = (InputMethodManager) getSystemService(Context.INPUT_METHOD_SERVICE);
        imm.showSoftInput(textEdit, InputMethodManager.SHOW_IMPLICIT);
    }
});

dialog.show();

是的，你可以用setOnFocusChangeListener来做，它会帮助你。

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);
        }
    }
});

我找到了这个例子http://android-codes-examples.blogspot.com/2011/11/show-or-hide-soft-keyboard-on-opening.html。在alert.show()之前添加以下代码。

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

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。

将这些方法放在Util类中，并在任何地方使用。

科特林

fun hideKeyboard(activity: Activity) {
    val view = activity.currentFocus
    val methodManager = activity.getSystemService(Context.INPUT_METHOD_SERVICE) as InputMethodManager
    assert(view != null)
    methodManager.hideSoftInputFromWindow(view!!.windowToken, InputMethodManager.HIDE_NOT_ALWAYS)
}

private fun showKeyboard(activity: Activity) {
    val view = activity.currentFocus
    val methodManager = activity.getSystemService(Context.INPUT_METHOD_SERVICE) as InputMethodManager
    assert(view != null)
    methodManager.showSoftInput(view, InputMethodManager.SHOW_IMPLICIT)
}

Java

public static void hideKeyboard(Activity activity) {
    View view = activity.getCurrentFocus();
    InputMethodManager methodManager = (InputMethodManager) activity.getSystemService(Context.INPUT_METHOD_SERVICE);
    assert methodManager != null && view != null;
    methodManager.hideSoftInputFromWindow(view.getWindowToken(), InputMethodManager.HIDE_NOT_ALWAYS);
}

private static void showKeyboard(Activity activity) {
    View view = activity.getCurrentFocus();
    InputMethodManager methodManager = (InputMethodManager) activity.getSystemService(Context.INPUT_METHOD_SERVICE);
    assert methodManager != null && view != null;
    methodManager.showSoftInput(view, InputMethodManager.SHOW_IMPLICIT);
}

问题似乎是，因为你输入文本的地方最初是隐藏的(或嵌套或其他)，AlertDialog自动设置标志WindowManager.LayoutParams。FLAG_ALT_FOCUSABLE_IM或WindowManager.LayoutParams。FLAG_NOT_FOCUSABLE，这样就不会触发软输入来显示。

解决这个问题的方法是添加以下内容:

(...)
// Create the dialog and show it
Dialog dialog = builder.create()
dialog.show();

// After show (this is important specially if you have a list, a pager or other view that uses a adapter), clear the flags and set the soft input mode
dialog.getWindow().clearFlags(WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE|WindowManager.LayoutParams.FLAG_ALT_FOCUSABLE_IM);
dialog.getWindow().setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_STATE_ALWAYS_VISIBLE);