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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
*
* @author johnny
*
*/ public class ThreeListViewActivity extends Activity {
private ListView mContentLv;
private OneAdapter adapter;
private 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
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
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 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
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 new ArrayList
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
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
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
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ListView中常用知识总结