Android之ListView控件
实现如图效果：1.水果名字，和水果照片
2.点击ListView 响应点击事件
首先写布局文件：
1 activity_main.xml给ListView设置id
<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"
tools:context=".MainActivity" >
<ListView
android:id="@+id/list_View"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
/>
</LinearLayout>
2 fruit_item.xml android:layout_gravity="center 让文字居中显示
<pre name="code" class="html"><?xml version="1.0" encoding="utf-8"?> <!-- 单元布局-->
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="horizontal"
>
<ImageView
android:id="@+id/fruit_image"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
/>
<TextView
android:id="@+id/fruit_name"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:layout_marginLeft="10dp"
/>
<!-- android:layout_gravity="center" 让文字居中显示 -->
</LinearLayout>
<span style="font-family: Arial, Helvetica, sans-serif;">布局写好了，然后就开始写java代码吧</span>Fruit.java
package com.example.listviewtest;
public class Fruit
{
private String name; //水果名称
private int imageId; //水果对应图片的资源id
public Fruit(String name, int imageId) //有参数的构造函数
{
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;
}
}
MainActivity.java
在MainActivity中 首先要有显示的资源文件在这里定义一个
private List<Fruit> fruitList = new ArrayList<Fruit>(); 接下来自定义一个适配器，这个适配器继承自ArrayAdapter，并将泛型制定为Fruit类
新建FruitAdapter
package com.example.listviewtest;
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.ImageView;
import android.widget.TextView;
public class FruitAdapter extends ArrayAdapter<Fruit> //将泛型指定为Fruit类
{
private int resourceId;
private ImageView fruitImage;
private TextView fruitName ;
private View view;
/*实现ArrayAdapter<>的方法
* ArrayAdapter重写了父类的一组构造函数，用于将上下文，ListView子项布局的id和数据都传递进来
* */
//1方法
public FruitAdapter(
Context context, //上下文
int textViewResourceId, //ListView子项布局的id
List<Fruit> objects) //数据
{
super(context, textViewResourceId, objects);
resourceId = textViewResourceId ;
}
//2又重写了getView（）方法
//这个方法是每个子项被滚动到屏幕内的时候被调用
@Override
public View getView(int position, View convertView, ViewGroup parent)
{
Fruit fruit = getItem(position);//首先通过getItem()获得当前项的Fruit实例
ViewHolder viewHolder;
if(convertView == null)//如果不空，调用缓存加载出来，如果为空独自获取数据加载
{ //然后使用LayoutInflater来为这个子项加载我们传入的布局
view = LayoutInflater.from(getContext()).inflate(resourceId, null);
viewHolder = new ViewHolder();
//接着调用的View的FindViewById()的方法分别获得ImageView和TextView的实例
viewHolder.fruitImage =(ImageView) view.findViewById(R.id.fruit_image);
viewHolder.fruitName =(TextView) view.findViewById(R.id.fruit_name);
view.setTag(viewHolder); //将viewHolder存储在view中
}
else
{
view =convertView;
viewHolder = (ViewHolder) view.getTag(); //重新获取viewHolder
}
/*
fruitImage =(ImageView) view.findViewById(R.id.fruit_image);
fruitName =(TextView) view.findViewById(R.id.fruit_name);*/
//再用它们的setImageResource(fruit.getImageId())，setText(fruit.getName());方法显示图片和文字
viewHolder.fruitImage.setImageResource(fruit.getImageId());
viewHolder.fruitName.setText(fruit.getName());
return view ;
}
class ViewHolder //这里为了提高效率，用一个ViewHolder类，来缓存，在上面做一个判断，
{
ImageView fruitImage;
TextView fruitName;
}
}
MainActivity.java
package com.example.listviewtest;
import java.util.ArrayList;
import java.util.List;
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.Window;
import android.widget.AdapterView;
import android.widget.Toast;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ListView;
public class MainActivity extends Activity
{
private List<Fruit> fruitList = new ArrayList<Fruit>();
@Override
protected void onCreate(Bundle savedInstanceState)
{
requestWindowFeature(Window.FEATURE_NO_TITLE);
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
initFruit(); //初始化水果的数据
FruitAdapter adapter = new FruitAdapter(getApplicationContext(),R.layout.fruit_item,fruitList);
ListView listview = (ListView) findViewById(R.id.list_View);
listview.setAdapter(adapter);
listview.setOnItemClickListener(new OnItemClickListener()
{
@Override
public void onItemClick(AdapterView<?> parent, View view, int position,long id)
{
Fruit fruit = fruitList.get(position);
Toast.makeText(MainActivity.this, "你他妈的点击了"+fruit.getName(), 0).show();
}
});
}
private void initFruit()
{
Fruit aa = new Fruit("aa", R.drawable.aa);
fruitList.add(aa);
Fruit bb = new Fruit("bb", R.drawable.bb);
fruitList.add(bb);
Fruit cc = new Fruit("cc", R.drawable.cc);
fruitList.add(cc);
Fruit ee = new Fruit("ee", R.drawable.ee);
fruitList.add(ee);
Fruit ff = new Fruit("ff", R.drawable.ff);
fruitList.add(ff);
Fruit gg = new Fruit("gg", R.drawable.gg);
fruitList.add(gg);
Fruit hh = new Fruit("hh", R.drawable.hh);
fruitList.add(hh);
Fruit ii = new Fruit("ii", R.drawable.ii);
fruitList.add(ii);
Fruit jj = new Fruit("jj", R.drawable.jj);
fruitList.add(jj);
Fruit ll = new Fruit("ll", R.drawable.ll);
fruitList.add(ll);
Fruit mm = new Fruit("mm", R.drawable.mm);
fruitList.add(mm);
}
}