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：