注册上下文菜单registerForContextMenu的用法

来源：互联网发布：c语言怎么判断奇偶编辑：程序博客网时间：2024/05/05 21:49

要实现ListView的长按点击事件，可以直接调用setOnLongClickListener,在onLongClick里面实现逻辑，也可以使用注册上下文菜单的方法，比如要实现下面的效果

可以在item的长按事件中弹出一个对话框或者popupwindow来实现，今天我们换一种方法

package com.example.test;import android.app.Activity;import android.os.Bundle;import android.view.ContextMenu;import android.view.ContextMenu.ContextMenuInfo;import android.view.MenuItem;import android.view.View;import android.widget.AdapterView.AdapterContextMenuInfo;import android.widget.ArrayAdapter;import android.widget.ListView;import android.widget.Toast;public class MainActivity extends Activity {private ListView mListView;private String msg[] = new String[] { "测试1", "测试2", "测试3", "测试4" };String number;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);mListView = (ListView) findViewById(R.id.listview);ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1, msg);mListView.setAdapter(adapter);registerForContextMenu(mListView);}@Overridepublic void onCreateContextMenu(ContextMenu menu, View v,ContextMenuInfo menuInfo) {super.onCreateContextMenu(menu, v, menuInfo);number = (String) mListView.getItemAtPosition(((AdapterContextMenuInfo) menuInfo).position);//获取listview的item对象getMenuInflater().inflate(R.menu.context_menu, menu);}@Overridepublic boolean onContextItemSelected(MenuItem item) {if (item.getItemId() == R.id.menu_item1) {Toast.makeText(this, number, Toast.LENGTH_SHORT).show();} else if (item.getItemId() == R.id.menu_item2) {Toast.makeText(this, "选项2被选择了", Toast.LENGTH_SHORT).show();}return super.onContextItemSelected(item);}}

长按测试2，显示上下文菜单，再点击菜单项1，显示一个吐司，效果如下

context_menu.xml

<?xml version="1.0" encoding="utf-8"?><menu xmlns:android="http://schemas.android.com/apk/res/android" >    <item        android:id="@+id/menu_item1"        android:icon="@drawable/avatar_default"                android:title="菜单项1"/>    <item        android:id="@+id/menu_item2"        android:icon="@drawable/avatar_default"        android:title="菜单项2"/></menu>

activity_main.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:background="@color/white"    android:paddingBottom="@dimen/activity_vertical_margin"    android:paddingLeft="@dimen/activity_horizontal_margin"    android:paddingRight="@dimen/activity_horizontal_margin"    android:paddingTop="@dimen/activity_vertical_margin"    tools:context="com.example.test.MainActivity" >    <ListView        android:id="@+id/listview"        android:layout_width="match_parent"        android:layout_height="wrap_content" /></RelativeLayout>

registerForContextMenu的源码

public void registerForContextMenu(View view) {        view.setOnCreateContextMenuListener(this);    }

可以看出，不只是ListView，只要是View就可以注册上下文菜单，打开setOnCreateContextMenuListener

 public void setOnCreateContextMenuListener(OnCreateContextMenuListener l) {        if (!isLongClickable()) {            setLongClickable(true);        }        getListenerInfo().mOnCreateContextMenuListener = l;    }

原来是注册了View的长按事件

1 0