自定義ListView使用的Adapter

自定義ListView所用的適配器Adapter.

Adapter是用於將數據集（字符串，圖片等）和視圖（Textview, Image等）進行映射。

ListView的實現需要兩個要素：1.數據集，2.適配器Adapter。

舉一個實例說明ListView的Adapter的自定義實現。

1.      數據集

使用的是List<Map<String,String>> list

數據集元素的添加方式如下：

Map<String,String>map = newHashMap<String,String>();

  map.put("name","Tom");

  map.put("age", "23");

list.add(map);

這樣就在數據集中添加了一個元素了。

 

2.  創建適配器

public class SelfDefineAdapter extends BaseAdapter{……}

adapter = new SelfDefineAdapter(this,list);

 

3.     給ListView設置適配器

listView.setAdapter(adapter);

 

貼上代碼：

MainActivity.java

package com.nuist.selfdefineadapter;

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.widget.ListView;

public class MainActivity extends Activity {
	
	private ListView listView;
	private List<Map<String,String>> list;
	/**
	 * 數組names和ages是用於填充數據集list的。
	 */
	private String[] names = {"Tom","Jerry","Jack"};
	private int[] ages = {32,4,56};
	
	private SelfDefineAdapter adapter;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        listView = (ListView)findViewById(R.id.list_people);
        list = getList(); //數據集，一個List
        adapter = new SelfDefineAdapter(this,list);  //創建適配器，傳遞了數據集list過去，用於映射到控件
        listView.setAdapter(adapter); //爲控件ListView設置適配器
    }

    /**
     * getList()就是講數組names和ages的內容放到了List中
     * @return
     */
    private List<Map<String,String>> getList(){
    	List<Map<String,String>> listItem = new ArrayList<Map<String,String>>();
    	for(int i=0;i<ages.length;i++){
    		Map<String,String> map = new HashMap<String,String>();
    		map.put("name", names[i]);
    		map.put("age", ages[i]+"");
    		listItem.add(map);
     	}
    	return listItem;
    }
}

自定義的Adapter:

package com.nuist.selfdefineadapter;

import java.util.List;
import java.util.Map;

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

public class SelfDefineAdapter extends BaseAdapter {

	private List<Map<String,String>> list; //數據集
	private Context context;
	private LayoutInflater listInflater;  //用於視圖填充器
	public final class ListRowView{  //對應list_raw.xml中的兩個TextView控件
		TextView name;
		TextView age;
	}
	public SelfDefineAdapter(Context context, List<Map<String,String>> list){
		this.context = context;
		listInflater = LayoutInflater.from(context);
		this.list = list;
	}
	@Override
	public int getCount() {
		// TODO Auto-generated method stub
		return list.size();
	}

	@Override
	public Object getItem(int position) {
		// TODO Auto-generated method stub
		return null;
	}

	@Override
	public long getItemId(int position) {
		// TODO Auto-generated method stub
		return 0;
	}

	@Override
	public View getView(int position, View convertView, ViewGroup parent) {
		// TODO Auto-generated method stub
		ListRowView listRowView = null;
		if(convertView == null){
			listRowView = new ListRowView();
			convertView  = listInflater.inflate(R.layout.list_raw, null);
			listRowView.name = (TextView)convertView.findViewById(R.id.name);
			listRowView.age = (TextView)convertView.findViewById(R.id.age);
			convertView.setTag(listRowView);
		}else{
			listRowView = (ListRowView)convertView.getTag();
		}
		/**
		 * 將數據集中的數據和控件對應起來
		 */
		listRowView.name.setText((String)list.get(position).get("name"));
		listRowView.age.setText((String)list.get(position).get("age"));
		return convertView;
	}

}

main.xml

<LinearLayout 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:orientation="vertical">
    
	<ListView android:id="@+id/list_people"
	    android:layout_height="wrap_content"
	    android:layout_width="match_parent"
	    ></ListView>
</LinearLayout>

list_row.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/name"
    android:layout_height="wrap_content"
    android:layout_width="match_parent"/>

<TextView android:id="@+id/age"
    android:layout_height="wrap_content"
    android:layout_width="match_parent"/>
</LinearLayout>

運行的結果：