public class MainActivity extends Activity {
private ListView listview;
private List<String> dataList = new ArrayList<String>();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
listview = (ListView) findViewById(R.id.listview);
initData();
MyAdapter myAdapter = new MyAdapter();
listview.setAdapter(myAdapter);
//为listview设置点击监听
listview.setOnItemClickListener(new OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
//标题
if(position == 1|| position == 7){
return;
}
//数据
Toast.makeText(MainActivity.this, "点击了第"+position+"条", 0).show();
}
});
}
private void initData() {
for (int i = 0; i < 10; i++) {
dataList.add("第"+i+"条数据");
}
}
class MyAdapter extends BaseAdapter{
@Override
public int getCount() {
return dataList.size();
}
@Override
public Object getItem(int position) {
return dataList.get(position);
}
@Override
public long getItemId(int position) {
return position;
}
/*
* 总共显示10条数据 第2条和第8条显示文本 其他显示图片加文本(position)
*/
@Override
public View getView(int position, View convertView, ViewGroup parent) {
//注意:1.加载的是布局文件,返回的也是布局文件,
// 2.只有textview特殊能直接返回,imageView需要从布局中加载文件
//屏幕滑出去会自动复用
if(position == 1 || position == 7){
TextView textView = new TextView(MainActivity.this);
textView.setText(""+position);
textView.setTextSize(30);
textView.setTextColor(Color.BLUE);
return textView;
}
ViewHolder viewHolder = null ;
//如果复用的view不为空,并且能转化为子类布局文件,获取viewHolder对象,否则加载布局文件,重新进行设置复用的view
if(convertView != null&&convertView instanceof LinearLayout){
viewHolder = (ViewHolder) convertView.getTag();
viewHolder.tv_text.setText("+"+dataList.get(position));
}else{
//加载布局
viewHolder= new ViewHolder();
convertView = View.inflate(MainActivity.this, R.layout.listview_item01, null);
viewHolder.iv_image = (ImageView) convertView.findViewById(R.id.iv_image01);
viewHolder.tv_text = (TextView) convertView.findViewById(R.id.tv_text01);
viewHolder.tv_text.setText("+"+dataList.get(position));
convertView.setTag(viewHolder);
}
return convertView;
}
class ViewHolder{
private TextView tv_text;
private ImageView iv_image;
}
}
}
Instanceof对象与类比较运算符
语法: 对象 instanceof 类 向下转型(大转小)父转子,必须强行转
返回类型是boolean类型,非true即false
表示判断某个对象是否属于某个类
注意:这个比较运算符不能随便使用,必须用在类与类存在继承关系的时候使用
效果图: