这是ListView的主类，运行后在这个View页面是空的，不知道什么原因？

谢谢！！

package com.example.plant;

import java.util.ArrayList;

import java.util.HashMap;

import java.util.List;

import java.util.Map;

import android.app.Activity;

import android.os.Bundle;

import android.widget.ListView;

import android.widget.SimpleAdapter;

public class ViewFirst extends Activity{

private ListView listView;

private SimpleAdapter simAdapter;

private List<Map<String,Object>>dataList;

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.view1);

//初始化控件

listView=(ListView) findViewById(R.id.listView1);

dataList=new ArrayList<Map<String,Object>>();

simAdapter=new SimpleAdapter(this, getData(), R.layout.item1, 

 new String[]{"imageView1","textView1"},

new int[]{R.id.imageView1,R.id.textView1});

//加载适配器

listView.setAdapter(simAdapter);

}

//获取数据源的方法

private List<Map<String,Object>> getData() {

for(int i=0;i<20;i++){

Map<String,Object>map=new HashMap<String,Object>();

map.put("imageView1", R.drawable.ic_launcher);

map.put("textView1", "花卉");

dataList.add(map);

}

return dataList;

}

}