老师能帮我看一下 单选对话框哪儿出问题了吗，我用手机调试 单选对话框不会弹出来

package com.example.dateandtimedialog;

import android.app.AlertDialog;
import android.app.DatePickerDialog;
import android.content.DialogInterface;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.DatePicker;
import android.widget.TextView;
import android.widget.Toast;


import java.util.Calendar;


public class MainActivity extends AppCompatActivity {


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        TextView tc=findViewById(R.id.text_view);
    }

    public void myClick(View view){
        switch (view.getId()){
            case R.id.date_set_dialog:
                DatePickerDialog dll= new DatePickerDialog(MainActivity.this, new DatePickerDialog.OnDateSetListener() {
                    @Override
                    public void onDateSet(DatePicker view, int year, int month, int dayOfMonth) {
                        Toast.makeText(MainActivity.this,Integer.toString(year)+"年"+Integer.toString(month+1)+"月"+Integer.toString(dayOfMonth)+"日",Toast.LENGTH_LONG).show();
                    }
                }, Calendar.DAY_OF_YEAR,Calendar.DAY_OF_MONTH,Calendar.DATE);
                dll.show();
                break;
            case R.id.sex_select_dialog:
                AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this);
                builder.setTitle("性别选择");
                builder.setIcon(R.drawable.ic_launcher_background);
                builder.setSingleChoiceItems(R.array.sex_string,android.R.layout.simple_selectable_list_item, new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        Toast.makeText(MainActivity.this,"你选择了："+Integer.toString(which),Toast.LENGTH_SHORT).show();
                        dialog.dismiss();
                    }
                });
                builder.show();

                break;

        }

    }


}

<resources>
    <string name="app_name">DateAndTimeDialog</string>
    <string-array name="sex_string">
        <item>男</item>
        <item>女</item>
        <item>性别未知</item>
        <item>你猜</item>
    </string-array>
    <string-array name="habbit_string">
        <item>编程</item>
        <item>LOL</item>
        <item>旅游</item>
        <item>篮球</item>
    </string-array>
</resources>