android ListView常用知识总结

先来看下项目主要内容：

ListView中填充数据：

重现添加数据后置顶，具体阐明了决解方案，如下：
刷新适配器后没有响应的错误现象，具体阐明了决解方案，如下：

正确示范一：

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 /** * 正确示范一（正确运用，修改原始对象对应引用也改变） * * @author johnny * */ public class ThreeListViewActivity extends Activity { private ListView mContentLv; private OneAdapter adapter; private ArrayList> arrayList= new ArrayList>(); @Override protected void onCreate(Bundle savedInstanceState) { // TODO Auto-generated method stub super .onCreate(savedInstanceState); setContentView(R.layout.activity_listview); mContentLv = (ListView) findViewById(R.id.lv_content); adapter= new OneAdapter( this ,arrayList); mContentLv.setAdapter(adapter); initData(); ToastUtils.show(getApplicationContext(), "6秒后延迟添加，刷新adapter" ); //开启异步线程 setData(); } private void setData() { new Thread( new Runnable() { @Override public void run() { // TODO Auto-generated method stub try { //做一些耗时的操作后添加数据，之后刷新adapter Thread.sleep( 6000 ); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } //可能这个时候才重网络上获取到了新数据，，现在开始添加数据 HashMap hashMap; for ( int i = 0 ; i < 5 ; i++) { hashMap = new HashMap(); if (i % 4 == 0 ) { hashMap.put( "name" , "大海" ); hashMap.put( "address" , "上海" ); } else if (i % 4 == 1 ) { hashMap.put( "name" , "老马" ); hashMap.put( "address" , "深圳" ); } else if (i % 4 == 2 ) { hashMap.put( "name" , "小三" ); hashMap.put( "address" , "东莞" ); } else if (i % 4 == 3 ) { hashMap.put( "name" , "老哥" ); hashMap.put( "address" , "北京" ); } arrayList.add(hashMap); } handler.sendEmptyMessage( 1 ); } }).start(); } Handler handler = new Handler(){ public void handleMessage(android.os.Message msg) { adapter.notifyDataSetChanged(); //没有重现设置adapter，只做了刷新数据，listview不会到顶。 ToastUtils.show(getApplicationContext(), "adapter共有" +adapter.getAllList().size()+ "个数据，activity共有" +arrayList.size()+ "个数据，刷新结束！" ); }; }; private void initData() { HashMap hashMap; for ( int i = 0 ; i < 15 ; i++) { hashMap = new HashMap(); if (i % 4 == 0 ) { hashMap.put( "name" , "小明" ); hashMap.put( "address" , "上海" ); } else if (i % 4 == 1 ) { hashMap.put( "name" , "老马" ); hashMap.put( "address" , "深圳" ); } else if (i % 4 == 2 ) { hashMap.put( "name" , "小三" ); hashMap.put( "address" , "东莞" ); } else if (i % 4 == 3 ) { hashMap.put( "name" , "老哥" ); hashMap.put( "address" , "北京" ); } arrayList.add(hashMap); } } }

正确示范二：

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 /** * 正确示范二（正确运用，Activity里面对象不用作Adapter原始对象，只做数据的备份。 * 这也是本人比较喜欢的写法，原因：很多时候我们会不经意间改变Activity里面的数据源后导致ListView的改变， * 导致出错后排除错误难解<正确示范一，当然也有好处，比如：改变Activity数据后，不需要再做多余的Adapter数据的更改，方便>） * * @注意这里只是数据添加方案本人赞成写法，具体完整结合adapter请移步个人推荐一或二<有错误示范，才能慢慢完善改变，错误何尝不是一种成长> * @author johnny * */ public class FourListViewActivity extends Activity { private ListView mContentLv; private OneAdapter adapter; @Override protected void onCreate(Bundle savedInstanceState) { // TODO Auto-generated method stub super .onCreate(savedInstanceState); setContentView(R.layout.activity_listview); mContentLv = (ListView) findViewById(R.id.lv_content); adapter= new OneAdapter( this ); mContentLv.setAdapter(adapter); initData(); ToastUtils.show(getApplicationContext(), "6秒后延迟添加，刷新adapter" ); //开启异步线程 setData(); } private void setData() { new Thread( new Runnable() { @Override public void run() { // TODO Auto-generated method stub try { //做一些耗时的操作后添加数据，之后刷新adapter Thread.sleep( 6000 ); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } ArrayList> arrayList= new ArrayList>(); //可能这个时候才重网络上获取到了新数据，，现在开始添加数据 HashMap hashMap; for ( int i = 0 ; i < 5 ; i++) { hashMap = new HashMap(); if (i % 4 == 0 ) { hashMap.put( "name" , "大海" ); hashMap.put( "address" , "上海" ); } else if (i % 4 == 1 ) { hashMap.put( "name" , "老马" ); hashMap.put( "address" , "深圳" ); } else if (i % 4 == 2 ) { hashMap.put( "name" , "小三" ); hashMap.put( "address" , "东莞" ); } else if (i % 4 == 3 ) { hashMap.put( "name" , "老哥" ); hashMap.put( "address" , "北京" ); } //这里添加的只是在临时数据存储的对象，adapter里面不属于同一个对象 arrayList.add(hashMap); } //和正确范例一区别在于此，每次都需要把数据copy到adapter里面 adapter.setAddList(arrayList); handler.sendEmptyMessage( 1 ); } }).start(); } Handler handler = new Handler(){ public void handleMessage(android.os.Message msg) { adapter.notifyDataSetChanged(); //没有重现设置adapter，只做了刷新数据，ListView不会到顶。 ToastUtils.show(getApplicationContext(), "adapter共有" +adapter.getAllList().size()+ "个数据。" ); }; }; private void initData() { ArrayList> arrayList= new ArrayList>(); HashMap hashMap; for ( int i = 0 ; i < 15 ; i++) { hashMap = new HashMap(); if (i % 4 == 0 ) { hashMap.put( "name" , "小明" ); hashMap.put( "address" , "上海" ); } else if (i % 4 == 1 ) { hashMap.put( "name" , "老马" ); hashMap.put( "address" , "深圳" ); } else if (i % 4 == 2 ) { hashMap.put( "name" , "小三" ); hashMap.put( "address" , "东莞" ); } else if (i % 4 == 3 ) { hashMap.put( "name" , "老哥" ); hashMap.put( "address" , "北京" ); } arrayList.add(hashMap); } adapter.setAddList(arrayList); } }

ListView 适配器推荐写法：

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 @Override public View getView( int position, View convertView, ViewGroup parent) { // TODO Auto-generated method stub View v = convertView; //判断是否为null，这是每个要做复用的都要写的 if (v == null ) { v = inflater.inflate(R.layout.lv_item, null ); } //相比之下 //写法太集中，没有细化 /*if (null == convertView) { holder = new ViewHolder(); convertView = inflater.inflate(R.layout.lv_item, null); holder.mNameTv = (TextView) convertView.findViewById(R.id.tv_name); holder.mAddressTv = (TextView) convertView.findViewById(R.id.tv_address); convertView.setTag(holder); } else { holder = (ViewHolder) convertView.getTag(); }*/ //简洁，把初始化控件放到了ViewHolder里面，是的getView方法更清晰简洁，只需要做数据的赋值和复杂的逻辑，没有混为一滩 ViewHolder holder = (ViewHolder) v.getTag(); if (holder == null ) { holder = new ViewHolder(v); v.setTag(holder); } HashMap hashMap = getItem(position); holder.mNameTv.setText(hashMap.get( "name" )); holder.mAddressTv.setText(hashMap.get( "address" )); return v; }

方法二：

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 @Override public View getView( int position, View convertView, ViewGroup parent) { // TODO Auto-generated method stub View v = convertView; //判断是否为null，这是每个要做复用的都要写的 if (v == null ) { v = inflater.inflate(R.layout.lv_item, null ); } //简洁,方便,快速 TextView mNameTv=ViewHolder.get(v, R.id.tv_name); TextView mAddressTv=ViewHolder.get(v, R.id.tv_address); HashMap hashMap = getItem(position); mNameTv.setText(hashMap.get( "name" )); mAddressTv.setText(hashMap.get( "address" )); return v; }

ListView中疑难杂症：

只做截图具体下载代码查看：不需要豆子

另链接单选删除帖子效果如下：

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ListView中常用知识总结

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