Android Studio之菜单栏制作 （四）

上下文菜单
1、重写Activity的onCreateContextMenu(ContextMenu menu, View v, ContextMenu.ContextMenuInfo menuInfo)方法。

2、调用Activity的registerForContextMenu(textView)方法为View组件注册上下文菜单

2、重写Activity的onContextItemSelected(MenuItem item)响应菜单项的选择操作，调用item.getItemId()获得被点击菜单项的ID，做出不同的响应

package com.example.myapplication;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.view.ContextMenu;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.SubMenu;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {
    //定义按钮的全局变量
    private Button button;
    private TextView textView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        // 绑定按钮的资源（利用id找到xml文件中的按钮）
        button = findViewById(R.id.button);
        textView = findViewById(R.id.textView);
        //为组件注册上下文菜单
        registerForContextMenu(textView);
    }

    //重写Activity的onCreateContextMenu()
    public void onCreateContextMenu(ContextMenu menu, View v, ContextMenu.ContextMenuInfo menuInfo){
        switch (v.getId()){
            case R.id.textView:
                menu.setHeaderTitle("分享到，，，");
                menu.add(0,200,0,"qq空间");
                menu.add(0,201,0,"朋友圈");
                SubMenu submenu = menu.addSubMenu(0,200,0,"微博");
                submenu.add(0,202,0,"新浪");
                submenu.add(0,203,0,"新浪");
                submenu.add(0,204,0,"新浪");
            default:
                break;
        }
        super.onCreateContextMenu(menu,v,menuInfo);
    }
    
    //重写Activity的onContextItemSelected()
    public boolean onContextItemSelected(MenuItem item){
        switch (item.getItemId()){
            case 200:
                Toast.makeText(MainActivity.this,"你选了一",Toast.LENGTH_LONG).show();
                break;
            case 201:
                Toast.makeText(MainActivity.this,"你选了二",Toast.LENGTH_LONG).show();
                break;
            case 203:
                Toast.makeText(MainActivity.this,"你选了三",Toast.LENGTH_LONG).show();
                break;
            case 204:
                Toast.makeText(MainActivity.this,"你选了四",Toast.LENGTH_LONG).show();
                break;
            default:
                return super.onOptionsItemSelected(item);
        }
        return true;
    }

}

效果图如下：（长按哦！）