数据库listview界面的显示

public class MainActivity extends Activity {

private SQLiteDatabase db;
private ListView lv;
private List<Person> list;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

//初始化listview控件
lv = (ListView) findViewById(R.id.lv);

DBHelper helper = new DBHelper(this, "persons.db", null, 1);

db = helper.getWritableDatabase();

}

public void insert(View v){

// db.execSQL(“insert into person (name)values(?)”, new String[]{“lisi”});

ContentValues values = new ContentValues();

Random r = new Random();

values.put(“name”, “zhangsan”+r.nextInt(100));

long rowId = db.insert(“person”, null, values);

System.out.println(“rowId=”+rowId);

Toast.makeText(this, “插入数据成功”, 0).show();

}

public void query(View v){

list = new ArrayList<Person>();
/**
* table 表名
* columns 查询的列
* selection 查询条件"id=1"
* selectionArgs 查询条件的值
* String groupBy
* String having
* String orderBy)
*
*/
Cursor cursor = db.query("person", new String[]{"id","name" }, null, null, null, null, null);

while(cursor.moveToNext()){

Person p = new Person();
int id = cursor.getInt(0);
p.setId(id);
String name = cursor.getString(1);
p.setName(name);
list.add(p);
System.out.println("id="+id+"; name="+name);
}

//把数据显示到列表
lv.setAdapter(new MyAdapter());

Toast.makeText(this, "查询数据成功", 0).show();
}

/**
*创建一个数据适配器，为listview填充数据
*/
private class MyAdapter extends BaseAdapter{

@Override
public int getCount() {

return list.size();
}

@Override
public View getView(int position, View convertView, ViewGroup parent) {
View view = null;
if(convertView != null){
view = convertView;
}
else{
view = View.inflate(MainActivity.this, R.layout.item, null);
}

TextView tv_id = (TextView) view.findViewById(R.id.tv_id);
TextView tv_name = (TextView) view.findViewById(R.id.tv_name);
Person p = list.get(position);

tv_id.setText(p.getId()+"");

tv_name.setText(p.getName());
return view;
}

@Override
public Object getItem(int position) {
// TODO Auto-generated method stub
return null;
}

@Override
public long getItemId(int position) {
// TODO Auto-generated method stub
return 0;
}

}

}