Android控件之ListView的使用

ListView是Android当中一个非常常用的数据显示控件。

第一种可以使用List<HashMap<String , Object>>，作为适配器的数据源来显示要显示的数据。

XML布局文件之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="vertical" >

<TextView
android:id="@+id/itemTitle"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:textSize="20dip" >
</TextView>

<TextView
android:id="@+id/itemText"
android:layout_width="fill_parent"
android:layout_height="wrap_content" >
</TextView>

</LinearLayout>

XML布局文件之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: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=".MainActivity" >

<ListView android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/MyListView">
</ListView>

</RelativeLayout>

JAVA源代码：

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;

import android.os.Bundle;
import android.app.Activity;
import android.widget.ListView;
import android.widget.SimpleAdapter;

public class MainActivity extends Activity {

private ListView listView = null;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
listView = (ListView) this.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", "这是一个标题");
map.put("itemText", "这是一个内容");
myList.add(map);
}
//新建i适配器把数据源加入适配器
SimpleAdapter simpleAdapter = new SimpleAdapter(this
, myList
, R.layout.item
, new String[] { "itemTitle" , "itemText" }
, new int[] { R.id.itemTitle , R.id.itemText});
//给list添加适配器
listView.setAdapter(simpleAdapter);
}

}

界面显示：



第二种可以自定义一个Adapter类。只要写一个类继承ArrayAdapter，然后实现它的构造函数XXAdapter(Context context, int resource , List objects)和 重写它的

getCount()，getItem(int position)，getItemId(int position)，getView(int position, View convertView, ViewGroup parent) 等方法即可。

XML布局文件之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: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=".MainActivity" >

<TextView
android:id="@+id/id"
android:layout_width="100dip"
android:layout_height="wrap_content"
android:layout_marginLeft="30dip"
android:textSize="20dip" />

<TextView
android:id="@+id/name"
android:layout_width="100dip"
android:layout_height="wrap_content"
android:layout_alignTop="@id/id"
android:layout_toRightOf="@id/id"
android:textSize="20dip" />

<TextView
android:id="@+id/age"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignTop="@id/name"
android:layout_toRightOf="@id/name"
android:textSize="20dip" />

</RelativeLayout>

JAVA源代码之Person.java

public class Person {

private String id;
private String name;
private String age;

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;
}

}

JAVA源代码之PersonAdapter.java

import java.util.List;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.TextView;

public class PersonAdapter extends ArrayAdapter {

private LayoutInflater layoutInflater = null;
private List<Person> persons;

public PersonAdapter(Context context, int resource , List objects) {
super(context, resource);
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
*/
@Override
public View getView(int position, View convertView, ViewGroup parent) {
//优化后
ViewHolder holder;
if(convertView == null){
convertView = layoutInflater.inflate(R.layout.activity_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;
}

private static class ViewHolder{
private TextView id;
private TextView name;
private TextView age;
}

}

JAVA源代码之MainActivity.java

import java.util.ArrayList;

import android.os.Bundle;
import android.app.ListActivity;
import android.view.View;
import android.widget.ListView;
import android.widget.Toast;

public class MainActivity extends ListActivity {

private ArrayList<Person> persons = new ArrayList<Person>();
private PersonAdapter personAdapter = null;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
initData();
/**
* 第一个参数：当前类的对象
* 第二个参数：布局文件
* 第三个参数：数据源（这里主要是实体对象的数据源）
*/
personAdapter = new PersonAdapter(MainActivity.this,
R.layout.activity_main, persons);
setListAdapter(personAdapter);
registerForContextMenu(getListView());
}

@Override
protected void onListItemClick(ListView listView, View view, int position,
long id) {
super.onListItemClick(listView, view, position, id);
Person person = persons.get(position);
Toast.makeText(
MainActivity.this,
person.getId() + ":" + person.getName() + ":" + person.getAge(),
Toast.LENGTH_LONG).show();
return;
}
/**
* 初始化数据源
* 在PersonAdapter里会对布局文件和这里的数据源进行绑定
*/
private void initData() {
persons.add(new Person("序号", "姓名", "年龄"));
persons.add(new Person("1", "chen1", "23"));
persons.add(new Person("2", "chen2", "23"));
persons.add(new Person("3", "chen3", "23"));
persons.add(new Person("4", "chen4", "23"));
persons.add(new Person("5", "chen5", "23"));
persons.add(new Person("6", "chen6", "23"));
}

}

界面显示：