JDBC返回空结果集

打击为虎作伥

我正在使用JDBC实现非常简单的数据库连接。
我创建了连接/句子并进行查询。我在调试器中检查句子的查询对象，以确认它正在发送正确的查询。然后，我再次检查数据库中的查询（直接从调试器中复制），以确保其返回数据。然而，返回结果集中在.next（）上给出false
( s$ ~, v. U3 }* E' |0 _这里有我遗漏的常见陷阱吗？
, r3 q; @- n' n9 N- zmyDB));               return returnList;   catch (SQLException e)              e.printStackTrace()；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；return null;   myDB));        }         return returnList;    } catch (SQLException e) {        e.printStackTrace();        return null;    }}还有myDB类(一个简单的包装程序使我能够将连接/语句代码放入任何项目)
public void sendQuery(String query){    this.query = query;    try              if(statement == null)              statement = connection.createStatement()；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；results = statement.executeQuery(query);   catch (SQLException e)              System.out.println(query);        currentError = e;        results = null;        printError(e,"querying");   public ResultSet getResults(){     return results;}编辑：根据建议，我主要修改了我的代码，但仍然有同样的问题。以下是简化具有相同问题的代码。
private boolean attemptLogin(String uName,String pWord)    ResultSet results;    try{          try            Class.forName("oracle.jdbc.driver.OracleDriver");      catch (ClassNotFoundException e)            e.printStackTrace();             connection =DriverManager.getConnection(connectionString,user,password);        PreparedStatement statement = connection.prepareStatement("select username from users where username='testuser'");        results = statement.executeQuery()；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；if(results != null && results.next()){              System.out.println("found a result");            statement.close()；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；    return true;             System.out.println("did not find a result");        statement.close()；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；return false;    }catch(SQLException e){          e.printStackTrace()；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；；return false;   我了消除错误的来源，我还对查询进行了硬编码。与以前相同的问题（所有查询都会发生）。调试器显示所有实例对象，不打印堆栈跟踪。此外，我可以在不同的项目中使用相同的代码（以及上面列出的更复杂的代码）。
                                                               
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