new AlertDialog.Builder(v.getContext()).setMessage("msg to display!").show();

带有编辑文本的警报对话框

AlertDialog.Builder builder = new AlertDialog.Builder(context);//Context is activity context
final EditText input = new EditText(context);
builder.setTitle(getString(R.string.remove_item_dialog_title));
        builder.setMessage(getString(R.string.dialog_message_remove_item));
 builder.setTitle(getString(R.string.update_qty));
            builder.setMessage("");
            LinearLayout.LayoutParams lp = new LinearLayout.LayoutParams(
                    LinearLayout.LayoutParams.MATCH_PARENT,
                    LinearLayout.LayoutParams.MATCH_PARENT);
            input.setLayoutParams(lp);
            input.setHint(getString(R.string.enter_qty));
            input.setTextColor(ContextCompat.getColor(context, R.color.textColor));
            input.setInputType(InputType.TYPE_CLASS_NUMBER);
            input.setText("String in edit text you want");
            builder.setView(input);
   builder.setPositiveButton(getString(android.R.string.ok),
                (dialog, which) -> {

//Positive button click event
  });

 builder.setNegativeButton(getString(android.R.string.cancel),
                (dialog, which) -> {
//Negative button click event
                });
        AlertDialog dialog = builder.create();
        dialog.show();

你可以使用下面的代码:

AlertDialog.Builder alertDialog2 = new AlertDialog.Builder(
    AlertDialogActivity.this);

// Setting Dialog Title
alertDialog2.setTitle("Confirm Delete...");

// Setting Dialog Message
alertDialog2.setMessage("Are you sure you want delete this file?");

// Setting Icon to Dialog
alertDialog2.setIcon(R.drawable.delete);

// Setting Positive "Yes" Btn
alertDialog2.setPositiveButton("YES",
    new DialogInterface.OnClickListener() {
        public void onClick(DialogInterface dialog, int which) {
            // Write your code here to execute after dialog
            Toast.makeText(getApplicationContext(),
                           "You clicked on YES", Toast.LENGTH_SHORT)
                    .show();
        }
    });

// Setting Negative "NO" Btn
alertDialog2.setNegativeButton("NO",
    new DialogInterface.OnClickListener() {
        public void onClick(DialogInterface dialog, int which) {
            // Write your code here to execute after dialog
            Toast.makeText(getApplicationContext(),
                           "You clicked on NO", Toast.LENGTH_SHORT)
                    .show();
            dialog.cancel();
        }
    });

// Showing Alert Dialog
alertDialog2.show();

   new AlertDialog.Builder(v.getContext()).setMessage("msg to display!").show();

public void showSimpleDialog(View view) {
    // Use the Builder class for convenient dialog construction
    AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this);
    builder.setCancelable(false);
    builder.setTitle("AlertDialog Title");
    builder.setMessage("Simple Dialog Message");
    builder.setPositiveButton("OK!!!", new DialogInterface.OnClickListener() {
        @Override
        public void onClick(DialogInterface dialog, int id) {
            //
        }
    })
    .setNegativeButton("Cancel ", new DialogInterface.OnClickListener() {
        @Override
        public void onClick(DialogInterface dialog, int which) {

        }
    });

    // Create the AlertDialog object and return it
    builder.create().show();
}

也可以看看我的关于Android对话的博客，你会在这里找到所有的细节:http://www.fahmapps.com/2016/09/26/dialogs-in-android-part1/。

现在最好使用DialogFragment而不是直接创建AlertDialog。

怎么做?参见:https://stackoverflow.com/a/21032871/1390874 为什么?参见:https://stackoverflow.com/a/13765411/1390874