Android Studio创建选项菜单

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android">
<item android:title="发起群聊"
    android:id="@+id/mymenu_qunliao"></item>
    <item android:title="添加朋友"
        android:id="@+id/mymenu_addfriend"></item>
    <item android:title="扫一扫"
        android:id="@+id/mymenu_saoyisao"></item>
    <item android:title="收付款"
        android:id="@+id/mymenu_shoufukuan"></item>
    <item android:title="帮助与反馈"
        android:id="@+id/mymenu_help"></item>
</menu>

package com.example.a1108;

import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        initweight();
    }
    public boolean onCreateOptionsMenu(Menu menu)
    {
        MenuInflater mi=getMenuInflater();/*把文件变成Menu对象*/
        mi.inflate(R.menu.mymenu,menu);
        return true;
    }
    public boolean onOptionsItemSelected(MenuItem Item)
    {
        Toast toast;
        String info="";
        switch (Item.getItemId())
        {
            case R.id.mymenu_qunliao:
                info="发起群聊";
            break;
            case R.id.mymenu_addfriend:
                info="添加朋友";
            break;
            case  R.id.mymenu_saoyisao:
                info="扫一扫";
            break;
            case  R.id.mymenu_shoufukuan:
                info="收付款";
            break;
            case R.id.mymenu_help:
                info="帮助与反馈";
            break;
            default:
                return super.onOptionsItemSelected(Item);
        }
        toast= Toast.makeText(MainActivity.this,info,Toast.LENGTH_LONG);
        toast.show();
        return true;
    }
    void initweight(){

    }
}