1. 程式人生 > >android 中 Listview 和base adapter的運用。

android 中 Listview 和base adapter的運用。

一. listveiw是android中最常用的佈局元件之一,繼承自viewgroup。他和gridview是組成android的最常用的元件。

二. adapter分為4個可用的元件,有arrayAdapter,simpleAdapter,baseadapter,和資料庫遊標adapter,這裡主要介紹baseadapter

三.

四. 程式碼示例:

    1.在載入時查詢到listview

  2.new 一個adapter

  3.給listview設定adapter為這個剛剛new出來的adapter

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在第二步new一個adapter時,需要做以下幾點

  1.class一個新類,繼承自baseadapter

  2.因為baseadapter是介面,需要重寫4個方法。

  3.最關鍵的是重寫getview方法,

    a)如果convertview為空時,view.inflate解析一個資原始檔中檢視。

    b)解析一行資料,用javabean,取得當前行位置的資料。

      ShopInfo shopInfo = data.get(position);

    c)得到子view物件。    

       ImageView imageView = (ImageView) convertView.findViewById(R.id.iv_item_icon);
            TextView nameTV = (TextView) convertView.findViewById(R.id.tv_item_name);
            TextView contentTV = (TextView) convertView.findViewById(R.id.tv_item_content);

    d) 為子view物件,設定資料。

      imageView.setImageResource(shopInfo.getIcon());

      nameTV.setText(shopInfo.getName());
      contentTV.setText(shopInfo.getContent());


    e)返回convertview
      return convertView;

                 

package com.atguigu.l03_listview;

import java.util.ArrayList; import java.util.List; import android.app.Activity; import android.os.Bundle; import android.util.Log; import android.view.TextureView; import android.view.View; import android.view.ViewGroup; import android.widget.BaseAdapter; import android.widget.ImageView; import android.widget.ListView; import android.widget.TextView; public class MainActivity extends Activity { private ListView lv_main; private List<ShopInfo> data; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); lv_main = (ListView) findViewById(R.id.lv_main); //準備集合資料 data = new ArrayList<ShopInfo>(); data.add(new ShopInfo(R.drawable.f1, "name----1", "content----1")); data.add(new ShopInfo(R.drawable.f2, "name----2", "content----2")); data.add(new ShopInfo(R.drawable.f3, "name----3", "content----3")); data.add(new ShopInfo(R.drawable.f4, "name----4", "content----4")); data.add(new ShopInfo(R.drawable.f5, "name----5", "content----5")); data.add(new ShopInfo(R.drawable.f6, "name----6", "content----6")); data.add(new ShopInfo(R.drawable.f7, "name----7", "content----7")); data.add(new ShopInfo(R.drawable.f8, "name----8", "content----8")); data.add(new ShopInfo(R.drawable.f9, "name----9", "content----9")); data.add(new ShopInfo(R.drawable.f10, "name----10", "content----10")); //準備BaseAdapter物件 MyAdapter adapter = new MyAdapter(); //設定Adapter顯示列表 lv_main.setAdapter(adapter); } class MyAdapter extends BaseAdapter { //返回集合資料的數量 @Override public int getCount() { Log.e("TAG", "getCount()"); return data.size(); } //返回指定下標對應的資料物件 @Override public Object getItem(int position) { return data.get(position); } @Override public long getItemId(int position) { return 0; } /** * 返回指定下標所對應的item的View物件 * position : 下標 * convertView : 可複用的快取Item檢視物件, 前n+1個為null * parent : ListView物件 */ @Override public View getView(int position, View convertView, ViewGroup parent) { //Log.e("TAG", "getView() position="+position+" convertView="+convertView); //如果沒有複用的 if(convertView==null) { Log.e("TAG", "getView() position="+position+" convertView="+convertView); //載入item的佈局, 得到View物件 convertView = View.inflate(MainActivity.this, R.layout.item_simple_adapter, null); } //根據position設定對應的資料 //得到當前行的資料物件 ShopInfo shopInfo = data.get(position); //得到子View物件 ImageView imageView = (ImageView) convertView.findViewById(R.id.iv_item_icon); TextView nameTV = (TextView) convertView.findViewById(R.id.tv_item_name); TextView contentTV = (TextView) convertView.findViewById(R.id.tv_item_content); //設定資料 imageView.setImageResource(shopInfo.getIcon()); nameTV.setText(shopInfo.getName()); contentTV.setText(shopInfo.getContent()); return convertView; } } }

 

 

bean:

package com.atguigu.l03_listview;

/**
 * 每行Item的資料資訊封裝類
 * @author 張曉飛
 *
 */
public class ShopInfo {

    private int icon;
    private String name;
    private String content;

    public ShopInfo(int icon, String name, String content) {
        super();
        this.icon = icon;
        this.name = name;
        this.content = content;
    }

    public ShopInfo() {
        super();
    }

    public int getIcon() {
        return icon;
    }

    public void setIcon(int icon) {
        this.icon = icon;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getContent() {
        return content;
    }

    public void setContent(String content) {
        this.content = content;
    }

    @Override
    public String toString() {
        return "ShopInfo [icon=" + icon + ", name=" + name + ", content="
                + content + "]";
    }

}

 

         

佈局檔案:item_simple_adapter
<?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="wrap_content"
    android:orientation="horizontal" >

    <ImageView
        android:id="@+id/iv_item_icon"
        android:layout_width="70dp"
        android:layout_height="70dp"
        android:src="@drawable/f1" />

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical" 
        android:gravity="center_vertical"
        android:layout_marginLeft="10dp">

        <TextView
            android:id="@+id/tv_item_name"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="TextView" />

        <TextView
            android:id="@+id/tv_item_content"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="TextView" />

    </LinearLayout>

</LinearLayout>