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android学习笔记——利用BaseAdapter生成40个列表项

2024-07-06 02:57:34   225人阅读

RT；

main.xml

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<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
              android:orientation="vertical"
              android:layout_width="match_parent"
              android:layout_height="match_parent"
        >
    <ListView
            android:id="@+id/myList"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            />
</LinearLayout>

MyActivity.java

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public class MyActivity extends Activity {
    /**
     * Called when the activity is first created.
     */
 
    ListView myList;
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        myList=(ListView)findViewById(R.id.myList);
        BaseAdapter adapter =new BaseAdapter() {
            @Override
            public int getCount() {
                //指定一共包含40个选项
                return 40;
            }
 
            @Override
            public Object getItem(int i) {
                return null;  //To change body of implemented methods use File | Settings | File Templates.
            }
//重写该方法，该方法的返回值将作为列表项的ID
            @Override
            public long getItemId(int i) {
                return i;  //To change body of implemented methods use File | Settings | File Templates.
            }
 
            @Override
            public View getView(int i, View view, ViewGroup viewGroup) {
          //创建一个LinerarLayout，并向其中添加两个组件
                LinearLayout line=new LinearLayout(MyActivity.this);
                line.setOrientation(0);
                ImageView image=new ImageView(MyActivity.this);
                image.setImageResource(R.drawable.ic_launcher);
                TextView text=new TextView(MyActivity.this);
                text.setText("第"+(i+1)+"个列表项");
                text.setTextSize(20);
                text.setTextColor(Color.RED);
                line.addView(image);
                line.addView(text);
                //返回LinearLayout实例
                return line;
            }
        };
        myList.setAdapter(adapter);
    }
}

　　效果如图：

创建一个BadeAdapter对象，扩展该对象需要重写如下4个方法

* getCount()：该方法的返回值控制该Adapter将会包含多少个列表项。

* getItem()：该方法的返回值决定第postion处的列表项的内容。

* getItemId(int i)：该方法的返回值决定第postion处的列表项的ID。

* getView(int i,View view,ViewGroup viewGroup): 该方法的返回值决定第i处的列表项组件


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