Android下ListView使用

 列表的显示需要三个元素：

1．ListVeiw 用来展示列表的View。

2．适配器 用来把数据映射到ListView上的中介。

3．数据    具体的将被映射的字符串，图片，或者基本组件。

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"    tools:context=".MainActivity" >    <ListView        android:id="@+id/lv"        android:layout_width="match_parent"        android:fastScrollEnabled="true"        android:layout_height="match_parent" >    </ListView></RelativeLayout>

一、BaseAdapter

package com.itheima.listview;import android.os.Bundle;import android.app.Activity;import android.database.DataSetObserver;import android.view.Menu;import android.view.View;import android.view.ViewGroup;import android.widget.BaseAdapter;import android.widget.ListAdapter;import android.widget.ListView;import android.widget.TextView;public class MainActivity extends Activity {@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);// [1]找到我们关心的控件ListView lv = (ListView) findViewById(R.id.lv);//[2]显示数据  和 其他普通控件(textview )有点区别 数据来源于数据适配器lv.setAdapter(new MyListAdapter());}//[3]定义listview的数据适配器 private class MyListAdapter extends BaseAdapter{//一共有多少条数据需要展示@Overridepublic int getCount() {return 1000000000;}//返回指定position位置对应的对象@Overridepublic Object getItem(int position) {return null;}//返回position位置对应id@Overridepublic long getItemId(int position) {return 0;}/** * 获取一个view  用来显示listview的数据  会作为listview的一个条目出现  *  * convertView 历史缓存对象 */@Overridepublic View getView(int position, View convertView, ViewGroup parent) {TextView tv ;if (convertView == null) {//创建新的view 对象 tv = new TextView(MainActivity.this);System.out.println("创建新的view 对象---"+position);}else{System.out.println("复用历史缓存 对象---"+position);tv = (TextView) convertView;}tv.setText("哈哈哈"+position);return tv;}}}

二、ArrayAdapter

item.xml

<?xml version="1.0" encoding="utf-8"?><TextView xmlns:android="http://schemas.android.com/apk/res/android"    android:id="@+id/textView1"    android:layout_width="wrap_content"    android:layout_height="wrap_content"    android:text="TextView"    android:textAppearance="?android:attr/textAppearanceLarge" />

package com.itheima.arrayadapter;import android.os.Bundle;import android.app.Activity;import android.widget.ArrayAdapter;import android.widget.ListView;public class MainActivity extends Activity{String objects[] = {"老张","老方","老黎","老毕","老刘","老韩","agjksd","sdgsdg"};@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);// [1]找到我们关心的控件ListView lv = (ListView) findViewById(R.id.lv);// [2]创建一个arrayAdapter //ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, R.layout.item, objects);ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, R.layout.item1, R.id.tv_name, objects);//[3]设置数据适配器    要会触类旁通lv.setAdapter(adapter);}}

三、SimpleAdapter

item.xml

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:orientation="horizontal" >    <TextView        android:id="@+id/tv_name"        android:layout_width="0dp"        android:layout_height="wrap_content"        android:text="agagag"        android:textSize="20sp"        android:layout_weight="1" />    <TextView        android:id="@+id/tv_phone"        android:layout_width="0dp"        android:layout_height="wrap_content"        android:text="agagag"         android:textSize="20sp"         android:textColor="#ff0000"        android:layout_weight="1" /></LinearLayout>

package com.itheima.simpleadapter;import java.util.ArrayList;import java.util.HashMap;import java.util.List;import java.util.Map;import android.os.Bundle;import android.app.Activity;import android.view.Menu;import android.view.View;import android.widget.ListView;import android.widget.SimpleAdapter;public class MainActivity extends Activity {@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);//[1]找到控件ListView lv = (ListView) findViewById(R.id.lv);//[1.1]准备listview 要显示的数据List<Map<String, String>> data = new ArrayList<Map<String,String>>();Map<String, String> map1 = new  HashMap<String, String>();map1.put("name", "张飞");map1.put("phone", "1388888");Map<String, String> map2 = new  HashMap<String, String>();map2.put("name", "赵云");map2.put("phone", "110");Map<String, String> map3 = new  HashMap<String, String>();map3.put("name", "貂蝉");map3.put("phone", "13882223");Map<String, String> map4 = new  HashMap<String, String>();map4.put("name", "关羽");map4.put("phone", "119");//[1.1]把map加入到集合中data.add(map1);data.add(map2);data.add(map3);data.add(map4);//[2]设置数据适配器  resource 我们定义的布局文件// from map集合的键SimpleAdapter adapter = new SimpleAdapter(getApplicationContext(), data, R.layout.item,new String[]{"name","phone"}, new int[]{R.id.tv_name,R.id.tv_phone});//[3]设置数据适配器 lv.setAdapter(adapter);}}