ListView学习（带图片）

ListView在安卓中是一个很重要的组件之一，下面让我们一起来学习一下吧！

一、图例

下载代码

GitHub下载地址：https://github.com/GXS1225/ListView_icon.git

二、步骤如下：

1.首先我们需要建立两个 xml文件

（1）在activity_main.xml中创建一个ListView

<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"
    tools:context=".MainActivity" >

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

</RelativeLayout>      

（2）在fruit_item中创建一个 ImageView 和一个TestView 组件

<?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/ivFruit"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:src="@drawable/apple_pic" />

    <TextView
        android:id="@+id/tvFruit"
        android:layout_gravity="center"
        android:layout_margin="10dp"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Apple" />
</LinearLayout>

2.Java中的代码（分析）

在MainActivity.java

（1）我们要准备好 数据源，这里的数据源指的是我们要用到的一些图片和文字信息，我们把它封装到了List中，方便使用
（2）创建Adapter适配器 FruitAdapter adapter=new FruitAdapter( 当前文本 , fruit_item布局 ,
（3）绑定AdapterView和Adapter 注意：
Toast.makeText(MainActivity.this, fruit.getName()
Toast.LENGTH_SHORT).show(); 这是一个点击事件，显示当前一列水果的名称，利用 吐丝 点击显示水果的名称
FruitAdapter 是一个自定义的Adapter

代码如下：

package com.example.ui_listview01;
import java.util.ArrayList;
import java.util.List;
import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;
import android.view.View;
import android.widget.AdapterView;
import android.widget.Toast;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ListView;
import com.example.ui_listview01.adpater.FruitAdapter;
import com.example.ui_listview01.model.Fruit;
public class MainActivity extends Activity {
    private ListView lvFruits;
    //1.准备好数据源
    private List<Fruit> fruitList = new ArrayList<Fruit>();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //1.准备好数据源
        initFruits();

        lvFruits = (ListView) findViewById(R.id.lvFruits);

        //2.创建Adapter
        FruitAdapter adapter=new FruitAdapter(this, R.layout.fruit_item,fruitList);

        //3.绑定AdapterView和Adapter之间的关联
        lvFruits.setAdapter(adapter);
        lvFruits.setOnItemClickListener(new OnItemClickListener() {

            @Override
            public void onItemClick(AdapterView<?> adapterView, View view, int position,
                    long id) {
                Fruit fruit=    fruitList.get(position);
                Toast.makeText(MainActivity.this, fruit.getName(), Toast.LENGTH_SHORT).show();
            }
        });


    }
    private void initFruits() {
        Fruit apple = new Fruit("Apple", R.drawable.apple_pic);
        fruitList.add(apple);
        Fruit banana = new Fruit("Banana", R.drawable.banana_pic);
        fruitList.add(banana);
        Fruit orange = new Fruit("Orange", R.drawable.orange_pic);
        fruitList.add(orange);
        Fruit watermelon = new Fruit("Watermelon", R.drawable.watermelon_pic);
        fruitList.add(watermelon);
        Fruit pear = new Fruit("Pear", R.drawable.pear_pic);
        fruitList.add(pear);
        Fruit grape = new Fruit("Grape", R.drawable.grape_pic);
        fruitList.add(grape);
        Fruit pineapple = new Fruit("Pineapple", R.drawable.pineapple_pic);
        fruitList.add(pineapple);
        Fruit strawberry = new Fruit("Strawberry", R.drawable.strawberry_pic);
        fruitList.add(strawberry);
        Fruit cherry = new Fruit("Cherry", R.drawable.cherry_pic);
        fruitList.add(cherry);
        Fruit mango = new Fruit("Mango", R.drawable.mango_pic);
        fruitList.add(mango);

    }
}

FruitAdapter.java中

（1）FruitAdapter方法继承ArrayAdapter 需要重写getView方法
（2）getView()这个方法在每个子项被滚动到屏幕内的时候会被调用 getView( 当前位置, View convertView,
ViewGroup parent)

注意：在FruitAdapter的getView()方法中每次都将布局重新加载了一遍，当ListView快速滚动的时候这就会成为性能的瓶颈

代码如下：

package com.example.ui_listview01.adpater;
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.BaseAdapter;
import android.widget.ImageView;
import android.widget.TextView;
import com.example.ui_listview01.R;
import com.example.ui_listview01.model.Fruit;

public class FruitAdapter extends ArrayAdapter<Fruit> {
    private int resourceId;
    public FruitAdapter(Context context, int textViewResourceId,List<Fruit> data) {
        super(context, textViewResourceId, data);
        resourceId=textViewResourceId;
    }


    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        Fruit fruit = getItem(position);
        View view=LayoutInflater.from(getContext()).inflate(resourceId, null);
        ImageView ivFruit=(ImageView) view.findViewById(R.id.ivFruit);
        TextView tvFruit=(TextView) view.findViewById(R.id.tvFruit);
        ivFruit.setImageResource(fruit.getImageId());
        tvFruit.setText(fruit.getName());
        return view;
    }

}

Fruit.java中

代码如下：

package com.bzu.gxs.domain;

public class Fruit {
    private String name;
    private int imageId;

    /**
     * 
     */
    public Fruit(String name ,int imageId) {
        super();
        this.name=name;
        this.imageId=imageId;

    }

    public String getName() {
        return name;
    }

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

    public int getImageId() {
        return imageId;
    }

    public void setImageId(int imageId) {
        this.imageId = imageId;
    }


}

三、总结