ListView从入门到中级，android菜鸟级别，

来源：互联网发布：在北京干什么挣钱知乎编辑：程序博客网时间：2024/06/06 23:44

1.先简单写一个运用ListView 的小程序，

因为ListView是用来展示大量数据的，作为入门，我们就先将数据提供好，所以使用String数组。

1）先在activity_main.xml文件中写这样的程序，

2）编辑MainActivity.java程序

public class MainActivity extends Activity {

   private String[] data={"Apple","Banana","Qrange","Watermelon","Pear","Grape","Pineaaple","Strawberry","Cherry","Mango"};
   @Override
   protected void onCreate(Bundle savedInstanceState) {
       super.onCreate(savedInstanceState);
       setContentView(R.layout.activity_main);
       ArrayAdapter<String> adapter=new ArrayAdapter<String>(MainActivity.this, android.R.layout.simple_list_item_1,data);
       //数组中的数据是无法直接传递给LIstView的，需要借助适配器来完成
       //上面三个参数的意义分别是：当前上下文，ListView子项布局的id，要适配的数据。
       //可用于简单的显示一段文本
       ListView listView=(ListView)findViewById(R.id.list_view);
       listView.setAdapter(adapter);
   }
}

这样一个初步的小程序就写完了，下面的例子是在这个例子的基础上改写的

2.定制LiatView界面

1）定义一个实体类，作为ListView适配器的适配类型

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;//用来表示水果的名字
   }
   public int getImageId() {
       return imageId;//水果对应的图片资源的id
   }
}

2）为ListView的子项定义一个我们自定义的布局，在layout目录下，新建fruit_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">

<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="10dip"/>

</LinearLayout>

3）创建一个系定义的适配器，下面虽然是一个程序，小妞建议当成三个例子来练习，三个同样的方法，不过第一个方法没有进行任何的优化，后面两个方法分别进行了优化

public class FruitAdapter extends ArrayAdapter<Fruit> {
private int resourceId;

public FruitAdapter(Context context, int textViewResourceId,List<Fruit> objects) {

super(context, textViewResourceId,objects);

resourceId=textViewResourceId;

}

/*@Override

public View getView(int position, View convertView, ViewGroup parent) {

//这个方法在每个子项被滚动到屏幕内的时候都会被调用

// TODO Auto-generated method stub

Fruit fruit=getItem(position);//获取当前项的Fruit实例

View view=LayoutInflater.from(getContext()).inflate(resourceId, null);//为这个子项加载我们传入的布局

ImageView fruitImage=(ImageView)view.findViewById(R.id.fruit_image);

TextView fruitName=(TextView)view.findViewById(R.id.fruit_name);

fruitImage.setImageResource(fruit.getImageId());

fruitName.setText(fruit.getName());

return view;

}*/

//每次都去加载布局，需要进行优化

/*@Override

public View getView(int position, View convertView, ViewGroup parent) {

// TODO Auto-generated method stub

Fruit fruit=getItem(position);

View view;

if (convertView==null) {

view=LayoutInflater.from(getContext()).inflate(resourceId, null);//加载布局

}else {

view=convertView;//如果不为空，直接对convertView进行重用

}

ImageView fruitImage=(ImageView)view.findViewById(R.id.fruit_image);

TextView fruitName=(TextView)view.findViewById(R.id.fruit_name);//每次都去获取一次控件的实例

fruitImage.setImageResource(fruit.getImageId());

fruitName.setText(fruit.getName());

return view;

}*/

////每次都去获取一次控件的实例，继续进行优化

public View getView(int position, View convertView, ViewGroup parent) {

// TODO Auto-generated method stub

Fruit fruit=getItem(position);

View view;

ViewHolder viewHolder;

if (convertView==null) {

view=LayoutInflater.from(getContext()).inflate(resourceId, null);//加载布局

viewHolder=new ViewHolder();

viewHolder.fruitImage=(ImageView)view.findViewById(R.id.fruit_image);

viewHolder.fruitName=(TextView)view.findViewById(R.id.fruit_name);

view.setTag(viewHolder);

}else {

view=convertView;//如果不为空，直接对convertView进行重用

viewHolder=(ViewHolder)view.getTag();//重新获取ViewHolder

}

viewHolder.fruitImage.setImageResource(fruit.getImageId());

viewHolder.fruitName.setText(fruit.getName());

return view;

}

class ViewHolder{

ImageView fruitImage;

TextView fruitName;

}
}

4）修改MainActivity.java中的代码

public class MainActivity extends Activity {

private List<Fruit> fruitList=new ArrayList<Fruit>();

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

initFruits();//这是自定义的方法，用来初始化Fruit，

FruitAdapter adapter=new FruitAdapter(MainActivity.this, R.layout.fruit_item, fruitList);

ListView listView=(ListView)findViewById(R.id.list_view);

listView.setAdapter(adapter);

listView.setOnItemClickListener(new OnItemClickListener() {//这个是为每一次的点击设置监听器，这里使用了setOnClickListener为ListView注册了一个监听器

//每当用户点击屏幕中的任何一个子项时，都会掉哦那个onItemClick方法。通过Toast将获取到的水果的名字显示出来

@Override

public void onItemClick(AdapterView<?> parent, View view,

int position, long id) {

// TODO Auto-generated method stub

Fruit fruit=fruitList.get(position);

Toast.makeText(MainActivity.this, fruit.getName(), Toast.LENGTH_LONG).show();

}

});

}

private void initFruits() {

Fruit apple=new Fruit("Apple", R.drawable.ic_launcher);

fruitList.add(apple);

Fruit banana=new Fruit("Banana", R.drawable.ic_launcher);

fruitList.add(banana);

Fruit orange=new Fruit("Orange", R.drawable.ic_launcher);

fruitList.add(orange);

Fruit watermelon=new Fruit("Watermelon", R.drawable.ic_launcher);

fruitList.add(watermelon);

Fruit pear=new Fruit("Pear", R.drawable.ic_launcher);

fruitList.add(pear);

Fruit grape=new Fruit("Grape", R.drawable.ic_launcher);

fruitList.add(grape);

Fruit pineapple=new Fruit("Pineapple", R.drawable.ic_launcher);

fruitList.add(pineapple);

Fruit starwberry=new Fruit("Strawberry", R.drawable.ic_launcher);

fruitList.add(starwberry);

Fruit cherry=new Fruit("Cherry", R.drawable.ic_launcher);

fruitList.add(cherry);

Fruit mango=new Fruit("Mango", R.drawable.ic_launcher);

fruitList.add(mango);

}

@Override

public boolean onCreateOptionsMenu(Menu menu) {

// Inflate the menu; this adds items to the action bar if it is present.

getMenuInflater().inflate(R.menu.main, menu);

return true;

}

小妞的这篇博客，大家还是边看边敲吧，光看不顶用呀，小妞专属（摘自安卓《第一行代码 Android》）

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