Android:SQLite数据绑定ListView

public void showDbUpdata(){
mContext = MainActivity.this;
myDBHelper = new DbOpenHelper(mContext, "note.db", null, 1);

TextView note_main_content = (TextView) findViewById(R.id.content_main_textView_1);

mydb = myDBHelper.getWritableDatabase();
mydbcontent = new StringBuilder();

Cursor cursor = mydb.query("note", null, null, null, null, null, null);
//int columnsSize = cursor.getColumnCount();获取长度
List<Map<String, Object>> listitem = new ArrayList<Map<String, Object>>();
if (cursor.moveToFirst()) {
do {

int noteid = cursor.getInt(cursor.getColumnIndex("noteid"));
String title = cursor.getString(cursor.getColumnIndex("title"));
String fenlei = cursor.getString(cursor.getColumnIndex("fenlei"));
String date = cursor.getString(cursor.getColumnIndex("date"));
//mydbcontent.append( noteid + "：" + title+"：" + fenlei+"：" + date + "\n");

Map<String, Object> showitem = new HashMap<String, Object>();
showitem.put("icon", fenbie_icon_list[1]);
showitem.put("title", title);
showitem.put("fenlei", fenlei);
showitem.put("date", date);
showitem.put("number", 1);
listitem.add(showitem);
} while (cursor.moveToNext());
}
cursor.close();
//创建一个simpleAdapter
SimpleAdapter myAdapter = new SimpleAdapter(getApplicationContext(), listitem, R.layout.main_list_item, new String[]{"icon","title", "date","number"}, new int[]{R.id.imageView_note_icon,R.id.textView_title, R.id.textView_date,R.id.textView_number});
ListView listView = (ListView) findViewById(R.id.main_note_list);
listView.setAdapter(myAdapter);

// note_main_content.setText(mydbcontent);
}