ListView不同布局的item的复用方法详解

来源：互联网发布：浦东国税局知乎编辑：程序博客网时间：2024/06/04 20:45

废话不多说，直接上代码简介。

一、MainActivity和布局

public class HomeActivity extends Activity {@Bind(R.id.lv)ListView lv;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_home);ButterKnife.bind(this);lv.setAdapter(new ListViewAdapter(this));}}

<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"    tools:context="${relativePackage}.${activityClass}" >    <ListView        android:id="@+id/lv"        android:layout_width="match_parent"        android:layout_height="match_parent"        android:layout_marginLeft="10dp"        android:layout_marginRight="10dp"        android:divider="#ff7A4299"        android:dividerHeight="1px" /></RelativeLayout>

二、ListViewAdapter（适配器）

public class ListViewAdapter extends BaseAdapter {private final static String[] TITLE = { "個人資料", "活動記錄", "打卡", "投票", "現場抽獎", "購物車", "購買記錄", "登出" };private final static int[] ICON = { R.drawable.ico_12, R.drawable.ico_13, R.drawable.ico_14, R.drawable.ico_15,R.drawable.ico_16, R.drawable.ico_17, R.drawable.ico_18, R.drawable.ico_19 };private Context context;public ListViewAdapter(Context context) {super();this.context = context;}@Overridepublic int getCount() {return TITLE.length * 5;}@Overridepublic Object getItem(int position) {return TITLE[position % TITLE.length];}@Overridepublic long getItemId(int position) {return position;}@Overridepublic View getView(int position, View convertView, ViewGroup parent) {ViewHolder vh = null;// TITLE.length 等于8，总共有40个item。// 我们前20个用R.layout.item_listview，后20个用R.layout.item2_listviewif (position < 20) {// 要复用，这里就要做文章了// 这里，我们R.layout.item_listview泵出来，convertView =// View.inflate(context, R.layout.item_listview, null);// convertView这时是item第一种布局，我们知道它是LinearLayout，我们完全可以自定义一个Item1LinearLayout继承LinearLayout// 用Item1LinearLayout替代R.layout.item_listview里面的根布局LinearLayout// 这时，我们复用时，在判断convertView是否是Item1LinearLayout或者是它的子类就行了if (convertView != null && convertView instanceof Item1LinearLayout) {vh = (ViewHolder) convertView.getTag();} else {// 这里convertView==null 或者 convertView不是Item1LinearLayout不能复用// 重新泵布局1、R.layout.item_listviewconvertView = View.inflate(context, R.layout.item_listview, null);// 避免重复new对象ViewHolderif (vh == null) {vh = new ViewHolder();}vh.iconIv = (ImageView) convertView.findViewById(R.id.icon);vh.titleTv = (TextView) convertView.findViewById(R.id.title);convertView.setTag(vh);}vh.titleTv.setText(TITLE[position % TITLE.length]);vh.iconIv.setImageResource(ICON[position % TITLE.length]);} else {// 同上// 用Item2LinearLayout替代R.layout.item2_listview里面的根布局LinearLayout// 这时，我们复用时，在判断convertView是否是Item2LinearLayout或者是它的子类就行了if (convertView != null && convertView instanceof Item2LinearLayout) {vh = (ViewHolder) convertView.getTag();} else {// 这里convertView==null 或者 convertView不是Item2LinearLayout不能复用// 重新泵布2、R.layout.item2_listviewconvertView = View.inflate(context, R.layout.item2_listview, null);// 避免重复new对象ViewHolderif (vh == null) {vh = new ViewHolder();}vh.titleTv = (TextView) convertView.findViewById(R.id.title);convertView.setTag(vh);}vh.titleTv.setText(TITLE[position % TITLE.length]);}return convertView;}class ViewHolder {private ImageView iconIv;private TextView titleTv;}}

1.R.layout.item_listview

<com.example.picassso.view.Item1LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:layout_width="match_parent"    android:layout_height="wrap_content"    android:orientation="horizontal"    android:paddingBottom="12dp"    android:paddingTop="12dp" >    <ImageView        android:id="@+id/icon"        android:layout_width="30dp"        android:layout_height="30dp"        android:layout_gravity="center_vertical"        android:layout_marginLeft="10dp" />    <TextView        android:id="@+id/title"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_gravity="center_vertical"        android:layout_marginLeft="15dp"        android:text="個人資料"        android:textColor="#6000"        android:textSize="18sp" /></com.example.picassso.view.Item1LinearLayout>

2.R.layout.item2_listview

<com.example.picassso.view.Item2LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:layout_width="match_parent"    android:layout_height="wrap_content"    android:orientation="horizontal"    android:paddingBottom="12dp"    android:paddingTop="12dp" >    <TextView        android:id="@+id/title"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_gravity="center_vertical"        android:layout_marginLeft="15dp"        android:text="個人資料"        android:textColor="#f00"        android:textSize="18sp" /></com.example.picassso.view.Item2LinearLayout>

3.Item1LinearLayout和Item2LinearLayout

public class Item1LinearLayout extends LinearLayout {public Item1LinearLayout(Context context) {super(context);// TODO Auto-generated constructor stub}public Item1LinearLayout(Context context, AttributeSet attrs) {super(context, attrs);// TODO Auto-generated constructor stub}public Item1LinearLayout(Context context, AttributeSet attrs, int defStyleAttr) {super(context, attrs, defStyleAttr);// TODO Auto-generated constructor stub}}

public class Item2LinearLayout extends LinearLayout {public Item2LinearLayout(Context context) {super(context);// TODO Auto-generated constructor stub}public Item2LinearLayout(Context context, AttributeSet attrs) {super(context, attrs);// TODO Auto-generated constructor stub}public Item2LinearLayout(Context context, AttributeSet attrs, int defStyleAttr) {super(context, attrs, defStyleAttr);// TODO Auto-generated constructor stub}}

复用item就是这么个原理

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