edittext.setShowSoftInputOnFocus(真正的);是关于这个问题的最流畅的解决方案。

AlertDialog.Builder alertSearch = new AlertDialog.Builder(activity);
alertSearch.setIcon(R.drawable.ic_launcher);
alertSearch.setTitle("Search");
final EditText edittext = new EditText(activity);
edittext.setSingleLine();
edittext.setHint("...");
edittext.setText(SearchString);

在聚焦时设置键盘

edittext.setShowSoftInputOnFocus(true);

获得焦点

edittext.requestFocus();

And

alertSearch.setView(edittext);
alertSearch.setPositiveButton("OK", new DialogInterface.OnClickListener() {
    public void onClick(DialogInterface dialog, int whichButton) {
        // Do something
        act.recreate();
    }
});
alertSearch.show();

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); 

最初的问题涉及对话框和我的EditText是常规视图。无论如何，我认为这对你们大多数人也适用。所以这是对我有效的方法(上面建议的最高评价的方法对我没有任何作用)。下面是一个自定义的EditView，它可以做到这一点(子类化不是必需的，但我发现这对我的目的很方便，因为我还想在视图可见时捕获焦点)。

This is actually largely the same as the tidbecks answer. I actually didn't notice his answer at all as it had zero up votes. Then I was about to just comment his post, but it would have been too long, so I ended doing this post anyways. tidbeck points out that he's unsure how it works with devices having keyboards. I can confirm that the behaviour seems to be exactly the same in either case. That being such that on portrait mode the software keyboard gets popped up and on landscape it doesn't. Having the physical keyboard slid out or not makes no difference on my phone.

因为，我个人觉得行为有点尴尬，我选择使用:InputMethodManager.SHOW_FORCED。这是我想要的效果。无论朝向如何，键盘都是可见的，然而，至少在我的设备上，如果硬件键盘已经滑出，它不会弹出。

import android.app.Service;
import android.content.Context;
import android.util.AttributeSet;
import android.view.View;
import android.view.inputmethod.InputMethodManager;
import android.widget.EditText;

public class BringOutTheSoftInputOnFocusEditTextView extends EditText {

    protected InputMethodManager inputMethodManager;

    public BringOutTheSoftInputOnFocusEditTextView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        init();
    }

    public BringOutTheSoftInputOnFocusEditTextView(Context context, AttributeSet attrs) {
        super(context, attrs);
        init();
    }

    public BringOutTheSoftInputOnFocusEditTextView(Context context) {
        super(context);
        init();
    }

    private void init() {
        this.inputMethodManager = (InputMethodManager)getContext().getSystemService(Service.INPUT_METHOD_SERVICE);
        this.setOnFocusChangeListener(new View.OnFocusChangeListener() {
            @Override
            public void onFocusChange(View v, boolean hasFocus) {
                if (hasFocus) {
                    BringOutTheSoftInputOnFocusEditTextView.this.inputMethodManager.showSoftInput(BringOutTheSoftInputOnFocusEditTextView.this, InputMethodManager.SHOW_FORCED);
                }
            }
        });
    }

    @Override
    protected void onVisibilityChanged(View changedView, int visibility) {
        super.onVisibilityChanged(changedView, visibility);
        if (visibility == View.VISIBLE) {
            BringOutTheSoftInputOnFocusEditTextView.this.requestFocus();
        }
    }

}

这对我很有用。我为对话框设置了一个OnShowListener，在那个监听器中，我为文本字段设置了一个onFocusChangeListener，在那个FocusChangeListener中，我用100ms的延迟调用showSoftInput，然后删除FocusChangeListener，所以它只处理第一个焦点变化。

当调用dialog.show()时，OnShowListener被调用，它请求文本字段的焦点。当文本字段获得焦点时，将调用FocusChangeListener并最终显示键盘。

    val views = DialogBinding.inflate(layoutInflater) // layout with 'textfield'
    val dialog = MaterialAlertDialogBuilder(requireContext())
        .setTitle("Exercise")
        .setView(views.root)
        ...
        .create()
    dialog.setOnShowListener {
        views.textfield.onFocusChangeListener = View.OnFocusChangeListener { view, _ ->
            view.postDelayed({
                (view.context.getSystemService(Context.INPUT_METHOD_SERVICE) as InputMethodManager).showSoftInput(view, 0)
            }, 100)                
            views.textfield.onFocusChangeListener = null
        }
        views.repcount.requestFocus()
    }
    dialog.show()

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);

在AlertDialog中从EditText显示软键盘的问题可能是在AlertDialog.show()中，因为在显示AlertDialog之后应用了EditText。我不确定所有版本的API都是这样，但我认为解决方案来自API级别21，因为它来自AlertDialog.create()，它应该在AlertDialog.show()之前调用。

这是我对这种情况的最佳解决方案。首先，在某个地方创建:

    private int showKeyboard(View view) {
        final InputMethodManager inputManager = (InputMethodManager) requireActivity().getSystemService(Context.INPUT_METHOD_SERVICE);
        if (inputManager != null) {
            boolean isShown = inputManager.showSoftInput(view, InputMethodManager.SHOW_IMPLICIT); // flag=InputMethodManager.SHOW_IMPLICIT ili =
            return (isShown) ? 1: -1;
        }
        return 0;
    }

然后，在AlertDialog之后。生成器生成器= new AlertDialog.Builder(requireContext());继续:

    EditText editText = new EditText(requireContext());
    builder.setView(editText);
    // ... put positive-negative buttons, and etc ...
    AlertDialog dialog = builder.create(); // Create dialog from builder
    dialog.setCancelable(false); // If you need
    Handler handler = new Handler();
    dialog.setOnShowListener(new DialogInterface.OnShowListener() {
        @Override
        public void onShow(DialogInterface dialog) { // 1. When a dialog is displayed
            editText.requestFocus();
            Runnable runnable = new Runnable() { // create one runnable
                int counter = 0;
                public void run() {
                    int status = showKeyboard(editText); // 2. Call func.above for keyboard, but...
                    if(status == -1 && counter < 10){ handler.postDelayed(this, 100); counter ++; } // ...if it inst shown call again after 100ms
                }
            };
            runnable.run(); // Execute runnable first time here
        }
    });
    dialog.show();

不要忘记导入android.os.Handler;等等;-)

感谢大家的投票。