Java netbeans数据库检索数据并将其显示在另一个jframe文本字段中

我想检索我的数据，并在另一个jframe中显示它。如何将值传递到该点

public void connectDb() {
    try {
        //setting up driver for Java Derby - select the Driver Class from connection properties
        Class.forName("org.apache.derby.jdbc.ClientDriver");

        //setting up Database connection through DriverManager.getConnection(dbUrl, DBusername, DBpwd)
        con = DriverManager.getConnection(
                        "jdbc:derby://localhost:1527/dbshop", //DB URL from connection properties
                        "apiit", //DB username you gave when creating db
                        "apiit");   //DB password you gave when creating db

        //create java.sql.Statement from db connection to execute SQL queries
        stmt = con.createStatement();
    } catch (ClassNotFoundException ex) {

    } catch (SQLException ex) {
        System.out.println("Error in file");
    }
}//end connectDb()

public void updatePassword(String u) {
    boolean flag = false;
    try {

        //Sql UPDATE         column name   tabl name             clmn          equlng vrbl
        String sql = "select lastname from CUSTOMERDETAILS where FIRSTNAME='" + u + "'";

        //if the update query was successful it will return the no. of rows affected
        ResultSet rs = stmt.executeQuery(sql);
        System.out.println(sql);
    } catch (SQLException ex) {
        System.out.println("Error in updatePasswrd");
    }
    // return flag;
}

在

语句

上使用

PreparedStatement

。有关更多详细信息，请参阅

从查询中返回所需的值

例如

public String getLastName(String u) throws SQLException {
    String lastName = u;
    try (PreparedStatement ps = con.prepareStatement("select lastname from CUSTOMERDETAILS where FIRSTNAME=?")){
        ps.setString(1, u);
        try (ResultSet rs = ps.executeQuery()) {
            if (rs.next()) {
                lastName = rs.getString(1);
            }
        }
    }
    return lastName;
}

这只是返回客户的姓氏和匹配的名字。如果有多个，则只返回第一个结果

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没关系，但我想在另一个类中执行此操作，我如何将这些值传递到另一个JFrame？也许你应该有一个中央数据工厂，你可以从任何地方查询，那么为什么你不能调用getLastName方法并将结果应用到文本字段呢？