问题描述

SQLite读取全部数据

table中一共有11条记录，每个记录有三个内容"name","address","city"。现在要获取这些记录，但是我写的代码只能显示出一条记录，不知道怎么实现显示全部记录？

public void readData(View v)
    {
        DatabaseClass mydb = new DatabaseClass(this);
        SQLiteDatabase readdata = mydb.getReadableDatabase();
        TextView tv = (TextView)findViewById(R.id.readtext);
        Cursor c = readdata.rawQuery("select * from mylistdata", null);
        int[] elementId = {R.id.textView1, R.id.textView2, R.id.textView3};
        if(c !=null)
        {
            c.moveToFirst();
            while(c.isAfterLast() == false)
            {
                listData = new ArrayList<GenericListItem>();
                String name = c.getString(c.getColumnIndex(DatabaseClass.NAME));
                String address = c.getString(c.getColumnIndex(DatabaseClass.ADDRESS));
                String city = c.getString(c.getColumnIndex(DatabaseClass.CITY));
                listData.add(new GenericListItem(new String[]{name,address,city}));
                listAdapter = new GenericListAdapter(getApplicationContext(), R.layout.list_layout, listData, elementId);
                result.setAdapter(listAdapter);
                c.moveToNext();
            }

        }

解决方案

要把Adapter放到循环前初始化，然后最后再加载（调用setAdapter()），否则每次都对ListView设置了一个新的Adapter，当然只能看到最后一次设置的值了

解决方案二：

在while循环外面初始化listData ArrayList:

    c.moveToFirst();
    listData = new ArrayList<GenericListItem>();
    while(c.isAfterLast() == false)
    {
       // add value here to listData
      c.moveToNext();
    }
   // set  listData datasource to GenericListAdapter here

   listAdapter = new GenericListAdapter(getApplicationContext(),
              R.layout.list_layout, listData, elementId);

   result.setAdapter(listAdapter);

解决方案三：

listData = new ArrayList<GenericListItem>();  //moved out of loop

 while(c.isAfterLast() == false)
        {
            String name = c.getString(c.getColumnIndex(DatabaseClass.NAME));
            String address = c.getString(c.getColumnIndex(DatabaseClass.ADDRESS));
            String city = c.getString(c.getColumnIndex(DatabaseClass.CITY));
            listData.add(new GenericListItem(new String[]{name,address,city}));
            listAdapter = new GenericListAdapter(getApplicationContext(), R.layout.list_layout, listData, elementId);
            c.moveToNext();
        }

        result.setAdapter(listAdapter);  // moved out of loop

我认为是循环的问题，你这样写看看