Android学习笔记-listview实现方式之BaseAdapter

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/ll_root"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <ListView
        android:id="@+id/lv"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical" >
    </ListView>

</LinearLayout>

<?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="60dip"
    android:gravity="center_vertical"
    android:orientation="horizontal" >

    <TextView
        android:id="@+id/tv_id"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginLeft="5dip"
        android:text="ID"
        android:textColor="#ff0000"
        android:textSize="18sp" />

    <LinearLayout
        android:layout_marginLeft="20dip"
        android:layout_width="fill_parent"
        android:layout_height="60dip"
        android:gravity="center_vertical"
        android:orientation="vertical" >

        <TextView
            android:id="@+id/tv_name"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginLeft="5dip"
            android:text="姓名"
            android:textColor="#000000"
            android:textSize="18sp" />

        <TextView
            android:id="@+id/tv_number"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginLeft="5dip"
            android:text="号码"
            android:textColor="#880000"
            android:textSize="18sp" />
    </LinearLayout>

</LinearLayout>

public class MainActivity extends Activity {
	private LinearLayout ll;
	private ListView lv;
	private  List<Person> persons;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        
        ll = (LinearLayout) findViewById(R.id.ll_root);
        lv = (ListView) findViewById(R.id.lv);
        //获取数据
        PersonDao dao = new PersonDao(this);
        //persons的类型是List<Person>
        persons = dao.findAll();
        
       
        lv.setAdapter(new MyAdapter());
  
    }
    //默认实现类simplexxx,defaultxxx,basexxx.
    //当集成借口比较多的时候，可以继承base,simple,defaule,这些开头
    private class MyAdapter extends BaseAdapter{

    	private static final String TAG = "MyAdapter";

		//控制listview里总共有多少条目
		@Override
		public int getCount() {
			// TODO Auto-generated method stub
			return persons.size();
		}

		@Override
		public Object getItem(int position) {
			// TODO Auto-generated method stub
			return null;
		}

		@Override
		public long getItemId(int position) {
			// TODO Auto-generated method stub
			return 0;
		}

		@Override
		public View getView(int position, View convertView, ViewGroup parent) {
		
			//得到某个位置的person对象。
			Person person = persons.get(position);
			//把xml加载进来
			View view = View.inflate(MainActivity.this, R.layout.listitem, null);
			
			//一定要在view对象中寻找孩子的id
			TextView tv_id = (TextView) view.findViewById(R.id.tv_id);
			TextView tv_name = (TextView) view.findViewById(R.id.tv_name);
			TextView tv_number = (TextView) view.findViewById(R.id.tv_number);
			
			//person.getId(),是int的，+"" ,int一定要转化成String类型的。
			//tv_id.setText(person.getId());会出错。
			tv_id.setText("ID: "+person.getId());
			tv_name.setText("姓名: "+person.getName());
			tv_number.setText("电话: "+person.getNumber());
			
			return view;
			
		}
    	
    }

}