安卓基础----ListView基础应用

package com.example.listview;

import com.lidroid.xutils.ViewUtils;
import com.lidroid.xutils.view.annotation.ViewInject;

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 lv;
private MyAdapter adapter;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
lv = (ListView) findViewById(R.id.lv);
adapter = new MyAdapter();
lv.setAdapter(adapter);
}

private class MyAdapter extends BaseAdapter {
/**
* listview的条目总数
*/
public int getCount() {
return 30;
}

/**
* 每个item的内容
*/
public View getView(int position, View convertView, ViewGroup parent) {
ViewHolder holder;
// 进行convertView条目的复用
if (convertView != null) {// 如果convertView不存在，进行填充
holder = (ViewHolder) convertView.getTag();// 对相同类型的item类型进行复用
} else {// 如果convertView存在，进行复用
convertView = View.inflate(MainActivity.this,
R.layout.item_list, null);
holder = new ViewHolder(convertView);
convertView.setTag(holder);
}

holder.tv.setText("条目" + position);//设置item里面的具体内容

return convertView;
}

public Object getItem(int position) {
return null;
}

public long getItemId(int position) {
return 0;
}

}

/**
* 每个item里面的控件，抽取成一个类，可以节省时间，优化的一方面
*
* @author JYcainiao
*
*/
private class ViewHolder {
@ViewInject(R.id.tv_item)//注解出item中的控件
private TextView tv;

public ViewHolder(View view) {
ViewUtils.inject(this, view);//注解必须用到   this代表当前的item，view用来注解
}

}

}

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".MainActivity" >

<ListView
android:fastScrollEnabled="true"
android:id="@+id/lv"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />

</RelativeLayout>

<?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" >

<TextView
android:id="@+id/tv_item"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />

</LinearLayout>