New to Java

I am totally new to JDBC programming using MySQL as the DB.
I have trouble updating values in the employee_bak table, when there is a key match with employee table.

import java.sql.*;

public class Employee {

public static Connection con;
	
    public static void main(String[] args) 
    {
        try 
		{
			Class.forName("com.mysql.jdbc.Driver");

			con = DriverManager.getConnection("jdbc:mysql://localhost/training","root", "");

			java.util.Date util_today = new java.util.Date();
			java.sql.Date sql_today = new java.sql.Date(util_today.getTime());

			Employee emp = new Employee();

			// Below statement should be executed only once
			emp.createEmployee("employee");
			emp.createEmployee("employee_bak");
			
			//pre-populating employee table
			//emp.insertEmployee("employee",1004,"John Smith",5671.34f,sql_today);
			//emp.insertEmployee("employee",1005,"Jane Doe",5000.86f, sql_today);
        	//emp.insertEmployee("employee",1034,"Mary Jane",6784.57f, sql_today);
        	//emp.insertEmployee("employee",1054,"James Seymour",4675.47f, sql_today);
        	//emp.insertEmployee("employee",1258,"Philip Rogue",5848.33f, sql_today);

			//pre-populating employee_bak table
			emp.insertEmployee("employee_bak",1004,"Jack Hand",5252.4f,sql_today);
			emp.insertEmployee("employee_bak",1034,"Mary Beth",5000.42f,sql_today);
			emp.insertEmployee("employee_bak",1258,"Phil Hersh",3500.65f,sql_today);
			
			emp.copyEmployeeTable(); // I can make it to this call, but get stuck inside
        	con.close();
        }
        catch(Exception e) { e.printStackTrace();}
    }

    public int createEmployee(String tname1) throws SQLException{
		Statement stmt = con.createStatement();
		int count = stmt.executeUpdate("CREATE TABLE " +tname1+" (emp_id INT, name VARCHAR(20), salary FLOAT, "+"doj DATE)");
		return count;
    }
    public int insertEmployee(String tname1, int emp_id1, String name1, float salary1, java.sql.Date doj1) throws SQLException{int count = 0;
   		PreparedStatement p;
   		p = con.prepareStatement("insert into "+tname1+" (emp_id, name, salary, doj) values(?,?,?,?) ");
   		p.setInt(1, emp_id1);
   		p.setString(2, name1);
   		p.setFloat(3, salary1);
   		p.setDate(4, doj1);

   		count = p.executeUpdate();
   		p.close();
   		return count;
    } 
    public int copyEmployeeTable() throws SQLException{
    	int count = 0;
       	Statement stat = con.createStatement();
        String sql = "SELECT emp_id, name, salary, doj FROM employee ORDER BY emp_id";
        String sql2 = "SELECT emp_id, name, salary, doj FROM employee_bak ORDER BY emp_id";
               
        ResultSet rs = stat.executeQuery(sql);
        ResultSet rs2 = stat.executeQuery(sql2);
        
        boolean found;
        while (rs.next()){ //err msg: Operation not allowed after ResultSet closed

        	found = false;
        	while (rs2.next()){ //compare the key emp_id, if there is match use an update query to match the values from employee table
        		if (rs.getInt("emp_id") == rs2.getInt("emp_id")){
        			found=true;
        			System.out.println("Found record in backup table\nUpdating record\n\n");
        			//use update method
count = stat.executeUpdate("Update employee_bak set name="+rs.getString("name")+",salary="+rs.getFloat("salary")+",doj="+rs.getDate("doj")+" WHERE emp_id="+rs.getInt("emp_id")+")");
        			break;
        		}
        	}
        }
        
        }
        rs.close();
        stat.close();
        return count;
    }
}

This is the code in its entirety.
Created 2 tables: employee and employee_bak.
Successfully pre-populated both tables.
I call the copyEmployeeTable method, if the keys match from both tables then update employee_bak from employee.
I get the err msg: Operation not allowed after ResultSet closed.
Plus, I am not sure if I am doing the executeUpdate properly.