Android控件之ListView用法实例详解

本文实例讲述了android控件之listview用法。分享给大家供大家参考。具体如下：

示例一：

在android开发中listview是比较常用的组件，它以列表的形式展示具体内容，并且能够根据数据的长度自适应显示。

main.xml布局文件：

<?xml version="1.0" encoding="utf-8"?>
<linearlayout android:id="@+id/linearlayout01"
  android:layout_width="fill_parent" android:layout_height="fill_parent"
  xmlns:android="http://schemas.android.com/apk/res/android">
  <listview android:layout_width="wrap_content"
    android:layout_height="wrap_content" 
    android:id="@+id/mylistview">
  </listview>
</linearlayout>

my_listitem.xml布局文件：

<?xml version="1.0" encoding="utf-8"?>
<linearlayout android:layout_width="fill_parent"
  xmlns:android="http://schemas.android.com/apk/res/android"
  android:orientation="vertical" 
  android:layout_height="wrap_content"
  android:id="@+id/mylistitem" 
  android:paddingbottom="3dip"
  android:paddingleft="10dip">
  <textview android:layout_height="wrap_content"
    android:layout_width="fill_parent" 
    android:id="@+id/itemtitle"
    android:textsize="20dip">
  </textview>
  <textview android:layout_height="wrap_content"
    android:layout_width="fill_parent" 
    android:id="@+id/itemtext">
  </textview>
</linearlayout>

lsactivity类：

package com.ljq.ls;
import java.util.arraylist;
import java.util.hashmap;
import java.util.list;
import android.app.activity;
import android.os.bundle;
import android.widget.listview;
import android.widget.simpleadapter;
public class lsactivity extends activity {
  private listview list = null;
  public void oncreate(bundle savedinstancestate) {
    super.oncreate(savedinstancestate);
    setcontentview(r.layout.main);
    list = (listview) findviewbyid(r.id.mylistview);
    //组织数据源
    list<hashmap<string, string>> mylist = new arraylist<hashmap<string, string>>();
    for(int i=0;i<10;i++) {
      hashmap<string, string> map = new hashmap<string, string>();
      map.put("itemtitle", "this is title");
      map.put("itemtext", "this is text");
      mylist.add(map);
    }
    //配置适配器
    simpleadapter adapter = new simpleadapter(this, 
     mylist,//数据源 
     r.layout.my_listitem,//显示布局
     new string[] {"itemtitle", "itemtext"}, //数据源的属性字段
     new int[] {r.id.itemtitle,r.id.itemtext}); //布局里的控件id
    //添加并且显示
    list.setadapter(adapter);
  }
}

运行结果如下图所示：

示例二：

目录结构

main.xml布局文件：

<?xml version="1.0" encoding="utf-8"?>
<!-- 使用相对布局 -->
<relativelayout
  xmlns:android="http://schemas.android.com/apk/res/android"
  android:orientation="vertical" 
  android:layout_width="wrap_content"
  android:layout_height="wrap_content">
  <textview android:layout_width="100dip"
    android:layout_height="wrap_content"
    android:layout_marginleft="30dip"
    android:textsize="20dip"
    android:id="@+id/id"/>
  <textview android:layout_width="100dip"
    android:layout_height="wrap_content"
    android:layout_aligntop="@id/id"
    android:layout_torightof="@id/id"
    android:textsize="20dip"
    android:id="@+id/name"/>
  <textview android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_aligntop="@id/name"
    android:layout_torightof="@id/name"
    android:textsize="20dip"
    android:id="@+id/age"/>
</relativelayout>

实体javabean：

package com.ljq.domain;
public class person {
  private string id;
  private string name;
  private string age;
  public person() {
    super();
  }
  public person(string id, string name, string age) {
    super();
    this.id = id;
    this.name = name;
    this.age = age;
  }
  public string getid() {
    return id;
  }
  public void setid(string id) {
    this.id = id;
  }
  public string getname() {
    return name;
  }
  public void setname(string name) {
    this.name = name;
  }
  public string getage() {
    return age;
  }
  public void setage(string age) {
    this.age = age;
  }
}

自定义适配器personadapter

package com.ljq.ls;
import java.util.list;
import com.ljq.domain.person;
import android.content.context;
import android.view.layoutinflater;
import android.view.view;
import android.view.viewgroup;
import android.widget.arrayadapter;
import android.widget.textview;
/**
 * listview加载adapter的过程
 * 
 * 1、先判断adapter有多少数据项，根据这个数据确定有多少个item
 * 
 * 2、确定每个item里加载哪个view
 * 
 * 3、在view里加载要显示的数据
 * 
 * @author jiqinlin
 *
 */
public class personadapter extends arrayadapter{
  private layoutinflater layoutinflater = null;
  private list<person> persons;
  public personadapter(context context, int textviewresourceid, list objects) {
    super(context, textviewresourceid, objects);
    layoutinflater = layoutinflater.from(context);
    persons = objects;
  }
  /**
   * 获取adapter里有多少个数据项
   */
  @override
  public int getcount() {
    return persons.size();
  }
  @override
  public object getitem(int position) {
    return persons.get(position);
  }
  @override
  public long getitemid(int position) {
    return position;
  } 
  /**
   * 创建显示的数据界面
   * 
   * adapter的作用就是listview界面与数据之间的桥梁，
   * 当列表里的每一项显示到页面时，都会调用adapter的getview方法返回一个view。
   * 想过没有？ 在我们的列表有1000000项时会是什么样的？是不是会占用极大的系统资源？
   */
  @override
  public view getview(int position, view convertview, viewgroup parent) {
    /*
    // 优化前
    viewholder holder = new viewholder();
    convertview = layoutinflater.inflate(r.layout.main, null);
    holder.id = (textview)convertview.findviewbyid(r.id.id);
    holder.name = (textview)convertview.findviewbyid(r.id.name);
    holder.age = (textview)convertview.findviewbyid(r.id.age);
    convertview.settag(holder);
    holder.id.settext(persons.get(position).getid());
    holder.name.settext(persons.get(position).getname());
    holder.age.settext(persons.get(position).getage());
    return convertview;
    */
    // 优化后
    viewholder holder;
    if(convertview == null){
      convertview = layoutinflater.inflate(r.layout.main, null);
      holder = new viewholder();
      holder.id = (textview)convertview.findviewbyid(r.id.id);
      holder.name = (textview)convertview.findviewbyid(r.id.name);
      holder.age = (textview)convertview.findviewbyid(r.id.age);
      convertview.settag(holder);
    }else{
      holder = (viewholder)convertview.gettag();
    }
    holder.id.settext(persons.get(position).getid());
    holder.name.settext(persons.get(position).getname());
    holder.age.settext(persons.get(position).getage());
    return convertview;
  }
  /**
   * 界面上的显示控件
   * 
   * @author jiqinlin
   *
   */
  private static class viewholder{
    private textview id;
    private textview name;
    private textview age;
  }
}

类lsactivity

package com.ljq.ls;
import java.util.arraylist;
import android.app.listactivity;
import android.os.bundle;
import android.view.view;
import android.widget.listview;
import android.widget.toast;
import com.ljq.domain.person;
public class lsactivity extends listactivity {
  private arraylist<person> persons = new arraylist<person>();
  private personadapter personadapter = null;
  @override
  public void oncreate(bundle savedinstancestate) {
    super.oncreate(savedinstancestate);
    
    initdata();
    personadapter =new personadapter(lsactivity.this, r.layout.main, persons);
    setlistadapter(personadapter);
    registerforcontextmenu(getlistview());
  }
  @override
  protected void onlistitemclick(listview l, view v, int position, long id) {
    super.onlistitemclick(l, v, position, id);
    person person = persons.get(position);
    toast.maketext(lsactivity.this, person.getid()+":"+person.getname()
        +":"+person.getage(), toast.length_long).show();
    return;
  }
  private void initdata(){
    persons.add(new person("序号", "姓名", "年龄"));
    persons.add(new person("1", "ljq1", "20"));
    persons.add(new person("2", "ljq2", "20"));
    persons.add(new person("3", "ljq3", "20"));
    persons.add(new person("4", "ljq4", "20"));
    persons.add(new person("5", "ljq5", "20"));
    persons.add(new person("6", "ljq6", "20"));
    persons.add(new person("7", "ljq7", "20"));
    persons.add(new person("8", "ljq8", "20"));
    persons.add(new person("9", "ljq9", "20"));
  }
}

运行结果

希望本文所述对大家的android程序设计有所帮助。