为ListView创建ContextMenu

最新推荐文章于 2021-05-27 05:58:09 发布

原创最新推荐文章于 2021-05-27 05:58:09 发布 · 1k 阅读

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文章标签：

#listview #layout #menu #encoding #android #java

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这篇博客展示了如何在Android应用中为ListView组件创建并处理ContextMenu。首先通过XML布局文件定义了一个包含ListView的界面，然后在Activity的onCreate方法中初始化ListView并设置Adapter。接着，注册ContextMenu，并在onCreateContextMenu中填充菜单项。最后，覆盖onContextItemSelected方法来响应用户在ListView上的长按操作，根据选择的菜单项更新TextView的内容。

ContextMenu称为上下文菜单，一般在控件上长按时弹出。今天我们学习ContextMenu的用法，这里与listview相结合，先在ListView显示几个Item,然后在Item上长按，弹出一个菜单（就是ContextMenu）,点击菜单上的项目，提示刚才长按的Item的Position。

main.xml文件

Java代码

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent" android:layout_height="fill_parent"
android:orientation="vertical">
<TextView android:id="@+id/text" android:text="zzz"
android:textSize="18sp" android:textColor="#FFFFFF"
android:layout_width="fill_parent" android:layout_height="wrap_content"/>
<ListView android:id="@+id/list"
android:layout_width="fill_parent" android:layout_height="fill_parent">
</ListView>
</LinearLayout>

菜单有3个条目，在/res/menu/test_menu.xml中定义，和OptionMenu差不多，只是没有Icon

Java代码

package com.hello.menu;
import android.app.Activity;
import android.os.Bundle;
import android.view.ContextMenu;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.view.ContextMenu.ContextMenuInfo;
import android.widget.AdapterView.AdapterContextMenuInfo;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.TextView;
public class ApiDemos extends Activity {
/** Called when the activity is first created. */
private TextView mTextView;
private ListView mListView;
private String [] values;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
mTextView = (TextView) findViewById(R.id.text);
//下面的代码用于初始化一些数据
values = new String[30];
StringBuilder sb = new StringBuilder("z");
for (int i = 0; i < values.length; i++) {
sb.append(i);
values[i] = sb.toString();
}
mListView = (ListView) findViewById(R.id.list);
mListView.setAdapter(new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, values));
mTextView.setText(String.valueOf(mListView.getAdapter().getCount()));
//为ListView注册ContextMenu
registerForContextMenu(mListView);
}
//创建ContextMenu
@Override
public void onCreateContextMenu(ContextMenu menu, View v,
ContextMenuInfo menuInfo) {
// TODO Auto-generated method stub
if (v.getId() == R.id.list) {
MenuInflater inflater = getMenuInflater();
menu.setHeaderTitle("contextView sample").setHeaderIcon(R.drawable.icon);
inflater.inflate(R.menu.test_menu, menu);
}
super.onCreateContextMenu(menu, v, menuInfo);
}
@Override
public boolean onContextItemSelected(MenuItem item) {
// TODO Auto-generated method stub
if (item.getMenuInfo() instanceof AdapterContextMenuInfo) {
AdapterContextMenuInfo menuInfo = (AdapterContextMenuInfo) item.getMenuInfo();
//处理菜单的点击事件
switch (item.getItemId()) {
case R.id.call:
mTextView.setText(item.getTitle().toString() + menuInfo.position);
break;
case R.id.cc:
mTextView.setText(item.getTitle().toString() + menuInfo.position);
break;
case R.id.poweroff :
mTextView.setText(item.getTitle().toString() + menuInfo.position);
break;
}
}
return super.onContextItemSelected(item);
}
}