一、ListView的简单用法
2. 训练目标
1) 掌握 ListView 控件的使用
2) 掌握 Adapter 桥梁的作用
实现步骤:
1)首先新建一个项目, 并让ADT 自动帮我们创建好活动。然后修改activity_main.xml 中的代码,如下所示:
-
<?xml version="1.0" encoding="utf-8"?>
-
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
-
xmlns:tools=
"http://schemas.android.com/tools"
-
android:id=
"@+id/activity_main"
-
android:layout_width=
"match_parent"
-
android:layout_height=
"match_parent"
-
tools:context=
"cn.edu.bu.a13lab07.MainActivity">
-
-
<ListView
-
android:layout_width=
"match_parent"
-
android:layout_height=
"match_parent"
-
android:id=
"@+id/list_view"
-
>
-
</ListView>
-
</LinearLayout>
在布局中加入ListView 控件,并为ListView 指定了一个id 设置成match_parent 占满整个空间
2)在MainActivity 中
-
public
class MainActivity extends Activity {
-
private String[] data = {
"Apple",
"Banana",
"Orange",
"Watermelon",
-
"Pear",
"Grape",
"Pineapple",
"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);
-
ListView listView = (ListView) findViewById(R.id.list_view);
-
listView.setAdapter(adapter);
-
}
-
}
(1)、在这里我运用了系统包含的一个TextView的布局文件:android.R.layout.simple_expandable_list_item_1,调用这个比较方便,
(2)、ArrayAdapter<String> adapter = new ArrayAdapter<String>( MainActivity.this, android.R.layout.simple_list_item_1, data); 的意思是:创建一个数组适配器的代码,里面有三个参数,第一个参数是上下文,就是当前的Activity, 第二个参数是android sdk中自己内置的一个布局,它里面只有一个TextView,这个参数是表明我们数组中每一条数据的布局是这个view,就是将每一条数据都显示在这个 view上面;第三个参数就是我们要显示的数据。listView会根据这三个参数,遍历data里面的每一条数据,读出一条,显示到第二 个参数对应的布局中,这样就形成了我们看到的listView.
(3)、ArrayAdapter是BaseAdapter的子类
3)运行效果图:
二、定制ListView界面
1.训练目标
1) 掌握 ListView 控件的使用
2) 掌握如何自定义 Adapter 的使用
2. 主要参考步骤及代码
1) 定义一个实体类 Fruit,作为 ListView 适配器的适配类型。
2) 为 ListView 的子项指定一个我们自定义的布局 fruit_item.xml。
3) 创建一个自定义的适配器 FruitAdapter,这个适配器继承自 ArrayAdapter。重写构造方法和 getView 方法。
4)在MainActivity中编写,初始化水果数据
1、定义一个实体类Fruit
-
package cn.edu.bu.a13lab07;
-
-
/**
-
* Created by lw on 2017/4/14.
-
*/
-
-
public
class Fruit {
-
private String name;
-
private
int imageId;
-
-
public Fruit(String name, int imageId) {
-
this.name = name;
-
this.imageId = imageId;
-
}
-
-
public String getName() {
-
return name;
-
}
-
-
public int getImageId() {
-
return imageId;
-
}
-
}
2、为 ListView 的子项指定一个我们自定义的布局 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、创建一个自定义的适配器 FruitAdapter,这个适配器继承自 ArrayAdapter。重写构造方法和 getView 方法。
-
package cn.edu.bu.a13lab07;
-
-
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;
-
-
import java.util.List;
-
-
/**
-
* Created by lw on 2017/4/14.
-
*/
-
-
public
class FruitAdapter extends ArrayAdapter{
-
private
final
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) {
-
Fruit fruit = (Fruit) getItem(position);
// 获取当前项的Fruit实例
-
View view = LayoutInflater.from(getContext()).inflate(resourceId,
null);
//实例化一个对象
-
ImageView fruitImage = (ImageView) view.findViewById(R.id.fruit_image);
//获取该布局内的图片视图
-
TextView fruitName = (TextView) view.findViewById(R.id.fruit_name);
//获取该布局内的文本视图
-
fruitImage.setImageResource(fruit.getImageId());
//为图片视图设置图片资源
-
fruitName.setText(fruit.getName());
//为文本视图设置文本内容
-
return view;
-
}
-
}
View view = LayoutInflater.from(getContext()).inflate(resourceId, null);使用Inflater对象来将布局文件解析成一个View
4、在MainActivity中编写,初始化水果数据
-
package cn.edu.bu.a13lab07;
-
-
import android.app.Activity;
-
import android.os.Bundle;
-
import android.widget.ArrayAdapter;
-
import android.widget.ListView;
-
-
import java.util.ArrayList;
-
import java.util.List;
-
-
-
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();
// 初始化水果数据
-
FruitAdapter adapter =
new FruitAdapter(MainActivity.
this, R.layout.fruit_item, fruitList);
-
ListView listView = (ListView) findViewById(R.id.list_view);
-
listView.setAdapter(adapter);
-
}
-
-
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);
-
}
-
}
5、运行效果图
这样一个简单的ListView界面就完成了