本文章主要介绍了Android控件之ListView探究二，具有不错的的参考价值，希望对您有所帮助，如解说有误或未考虑完全的地方，请您留言指出，谢谢！
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
原创文章，作者：6024010，如若转载，请注明出处：https://blog.ytso.com/228176.html