高手来看看这个鬼问题
public class UserDAOImpl implements UserDAO { public User Login(int userid,String password) { String sql = "select * from users where userid=? and password=?"; PreparedStatement ps = null; ResultSet rs = null; try { ConFactory.DateBaseConnection(); ps = ConFactory.getConnection().prepareStatement(sql); ps.setInt(1,userid); ps.setString(2, password); rs = ps.executeQuery(); if (rs.next()) { User LoginUser = new User(//这里明明搞了个实例了，怎么下面RETURN时说找不到LoginUser呢？其他地方都没问题 rs.getInt(1), rs.getString(2), rs.getString(3), rs.getInt(4)); } rs.close(); ps.close(); } catch (SQLException e) { e.printStackTrace(); System.out.println("public boolean Login(User user) fail!!!!!!!!"); } finally { ConFactory.closeConn(); } return LoginUser;//报错没有找到LoginUser。unresorve.. }}public class UserDAOImpl implements UserDAO { public User Login(int userid,String password) { String sql = "select * from users where userid=? and password=?"; PreparedStatement ps = null; ResultSet rs = null; User LoginUser=null//先在这里声明，你在try里面声明，然后在try外面用，当然不行 try { ConFactory.DateBaseConnection(); ps = ConFactory.getConnection().prepareStatement(sql); ps.setInt(1,userid); ps.setString(2, password); rs = ps.executeQuery(); if (rs.next()) { LoginUser = new User(//这里改 rs.getInt(1), rs.getString(2), rs.getString(3), rs.getInt(4)); } rs.close(); ps.close(); } catch (SQLException e) { e.printStackTrace(); System.out.println("public boolean Login(User user) fail!!!!!!!!"); } finally { ConFactory.closeConn(); } return LoginUser;//这样就不会报错了 }}