android——ListView功能的实现

1、main.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"
    android:orientation="vertical" >
    
    <ListView  android:id="@+id/personLV"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        
        />

</LinearLayout>

2、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"
    android:orientation="horizontal" >
    
    <TextView android:id="@+id/idTV"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_weight="1"
        android:padding="10dp"
         android:textSize="20sp"
        />
    
    <TextView android:id="@+id/nameTV"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_weight="2"
         android:padding="10dp"
         android:textSize="20sp"
        />
    
    <TextView android:id="@+id/balanceTV"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_weight="2"
         android:padding="10dp"
          android:textSize="20sp"
        />
   
</LinearLayout>

3、MainActivity

package com.njupt.listview;

import java.util.List;

import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ListView;
import android.widget.TextView;

public class MainActivity extends Activity {

	private ListView personLV;
	private List<Person> persons;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.main);
	    
		personLV = (ListView) findViewById(R.id.personLV);
		
		PersonDao dao = new PersonDao(this);
		
		persons = dao.queryAll(); 
		personLV.setAdapter(new MyBaseAdapter());//给ListView添加adapter，按照adapter中的方法给ListView添加条目
	}

	private class MyBaseAdapter extends BaseAdapter{// 定义Adapter, 把每个Person对象生成一个条目, 将所有条目装入ListView

		@Override
		public int getCount() {//获取条目数量
			return persons.size();
		}

		@Override
		public Object getItem(int position) {//获取指定对象
			return persons.get(position);
		}

		@Override
		public long getItemId(int position) {//获取指定对象的id
			return position;
		}

		@Override
		public View getView(int position, View convertView, ViewGroup parent) {// 返回指定位置上的条目, 条目会被自动添加到ListView中
			
			View item = View.inflate(getApplicationContext(), R.layout.item, null);// 根据布局文件创建View(LinearLayout)
			
			TextView idTV =  (TextView) item.findViewById(R.id.idTV);// 获取这个新生成的View中的TextView
			TextView nameTV = (TextView) item.findViewById(R.id.nameTV);
			TextView balanceTV = (TextView) item.findViewById(R.id.balanceTV);
			
			Person p = persons.get(position);// 根据位置获取Person对象
			idTV.setText(p.getId() + "");// 给TextView设置文本
			nameTV.setText(p.getName());
			balanceTV.setText(p.getBalance()+"");
			
			return item;
		}
		
		
	}
	@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;
	}

}

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结果如下所示：