为什么只出来了一行数据？

Question

public class SimpleAdapterActivity extends Activity { private SimpleAdapter sim_adapter; private List<Map<String,Object>>datalist; private ListView lv;  @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_listview); lv=(ListView) findViewById(R.id.lv1); //新建一个map键值对数据集合 datalist=new ArrayList<Map<String,Object>>(); //新建一个适配器  适配器加载数据源  sim_adapter=new SimpleAdapter(this, getData(), R.layout.simple, new String[]{"img1","tv1"} ,new int[]{R.id.img1,R.id.tv1}); //视图加载适配器 lv.setAdapter(sim_adapter); } //数据源 private List<Map<String,Object>> getData(){ Map<String,Object> map=new HashMap<String, Object>();//创建一个键值对对象 map.put("img1", R.drawable.img1);//添加键-值对 map.put("tv1", "可爱萝莉"); map.put("img2", R.drawable.img3); map.put("tv2", "功夫兔"); map.put("img3", R.drawable.img3); map.put("tv3", "小狐狸"); map.put("img4", R.drawable.img4); map.put("tv4", "元气少女"); datalist.add(map); return datalist; }}