这一段是ItemsDAO商品逻辑类中根据ID返回商品信息的方法，，一点一点码上去的不是复制粘贴的，和老师讲的一模一样，它提示我please add return statement，为何？
public Items getItemsById (int id) {
Connection conn = null;
PreparedStatement stmt = null;
ResultSet rs = null;
try {
conn = DBHelper.getConnection();
String sql = "select * from items where id=?";
stmt = conn.prepareStatement(sql);
stmt.setInt(1, id);
rs = stmt.executeQuery();
if (rs.next()) {
Items item = new Items();
item.setCity(rs.getString("city"));
item.setId(rs.getInt("id"));
item.setName(rs.getString("name"));
item.setNumber(rs.getInt("number"));
item.setPicture(rs.getString("picture"));
item.setPrice(rs.getInt("price"));
return item;
}else{
return null;
}
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
} finally {
if (stmt != null) {
try {
stmt.close();
stmt = null;
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
if (rs != null) {
try {
rs.close();
rs = null;
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}
Connection conn=null;
PreparedStatement stmt=null;
ResultSet rs=null;
try{
conn=DBhelper.getConnection();
String sql="select * from items where id=?;";
stmt=conn.prepareStatement(sql);
stmt.setInt(1, id);
rs=stmt.executeQuery();
if(rs.next()){
items item=new items();
item.setId(rs.getInt("id"));
item.setName(rs.getString("name"));
item.setCity(rs.getString("city"));
item.setNumber(rs.getInt("number"));
item.setPrice(rs.getInt("price"));
item.setPicture(rs.getString("picture"));
return item;
}
else{
return null;
}
}catch(Exception ex){
ex.printStackTrace();
return null;
}finally{
if(rs!=null){
try{
rs.close();
rs=null;
}catch(Exception ex){
ex.printStackTrace();
}
}
if(stmt!=null){
try{
stmt.close();//释放stmt内存
stmt=null;
}catch(Exception ex){
ex.printStackTrace();
}
}
where id=?;";一个分号没写
Connection conn=null;
PreparedStatement stmt=null;
ResultSet rs=null;
ArrayList<items> list=new ArrayList<items>();//商品集合
try{
conn=DBhelper.getConnection();
String sql="select * from items";
stmt=conn.prepareStatement(sql);
rs=stmt.executeQuery();
while(rs.next()){
items item=new items();
item.setId(rs.getInt("id"));
item.setName(rs.getString("name"));
item.setCity(rs.getString("city"));
item.setNumber(rs.getInt("number"));
item.setPrice(rs.getInt("price"));
item.setPicture(rs.getString("picture"));
list.add(item);
}
return list;
}catch(Exception ex){
ex.printStackTrace();
return null;
}finally{
if(rs!=null){
try{
rs.close();
rs=null;
}catch(Exception ex){
ex.printStackTrace();
}
}
if(stmt!=null){
try{
stmt.close();//释放stmt内存
stmt=null;
}catch(Exception ex){
ex.printStackTrace();
}
}