reduce my JTextField's height in gridlayout

[ocw91]

I was trying to reduce my jtextfield height, since it is for user to enter first name.
somehow when i run the code, the box is just too big, is there anyway to change the textfield height? i tried with setPrefferedSize but somehow it showing error, mayb i put it wrongly in a wrong place
Totally a beginner here....
here is my code

import java.util.*;
import javax.swing.*;
import javax.swing.JList;
import javax.swing.ButtonGroup;
import java.awt.*;
import java.awt.BorderLayout;

public class RegistrationSystem extends JPanel{

    JLabel lblfirstname = new JLabel("First Name:");
    JLabel lbllastname = new JLabel("Last Name:");
    JLabel lblage = new JLabel("Age:");
    JLabel lblgender = new JLabel("gender:");
    JLabel lblworkshop = new JLabel("Workshop:");
    JLabel lblhotelroom = new JLabel("Hotel:");
    JLabel lblmobphone = new JLabel("Phone(mob):");
    JLabel lblphone = new JLabel("Phone:");
    JLabel lblstudent = new JLabel("Student:");

    JTextField jtffirstname = new JTextField();


    JTextField jtflastname = new JTextField();
    JTextField jtfage = new JTextField();
    JTextField jtfmobphone = new JTextField();
    JTextField jtfphone = new JTextField();

    JPanel jpradiogender = new JPanel(new BorderLayout());
    JRadioButton jrbmale = new JRadioButton("Male");
    JRadioButton jrbfemale = new JRadioButton("Female");

    JPanel jpradiochoice = new JPanel(new BorderLayout());
    JRadioButton jrbyes = new JRadioButton("Yes");
    JRadioButton jrbno = new JRadioButton("No");

    JPanel jpcheckboxworkshop = new JPanel(new BorderLayout());
    JCheckBox jcbworkshop1 = new JCheckBox("The Future is Called the Sensor Web");
    JCheckBox jcbworkshop2 = new JCheckBox("Distributed Information Retrieved");
    JCheckBox jcbworkshop3 = new JCheckBox("Advanced Medical Technology");
    JCheckBox jcbdinner = new JCheckBox("Registering for openning night dinner with keynote speech");

    String hotel[] = {"None","Deluxe","Premier","Suite"};
    JList jlhotel = new JList(hotel);

    JButton jbtregister = new JButton("Register");

    public RegistrationSystem() {
    ButtonGroup genderGroup = new ButtonGroup();
    genderGroup.add(jrbmale);
    genderGroup.add(jrbfemale);
    jpradiogender.add(jrbmale,BorderLayout.WEST);
    jpradiogender.add(jrbfemale,BorderLayout.EAST);

    ButtonGroup studentGroup = new ButtonGroup();
    studentGroup.add(jrbyes);
    studentGroup.add(jrbno);
    jpradiochoice.add(jrbyes,BorderLayout.WEST);
    jpradiochoice.add(jrbno,BorderLayout.EAST);

    jpcheckboxworkshop.add(jcbworkshop1,BorderLayout.NORTH);
    jpcheckboxworkshop.add(jcbworkshop2,BorderLayout.CENTER);
    jpcheckboxworkshop.add(jcbworkshop3,BorderLayout.SOUTH);

    JScrollPane listScrollPane = new JScrollPane(jlhotel);

    jtffirstname.setBounds(200,50,20,20);

    JPanel jpmain = new JPanel(new GridLayout(10,2));
    jpmain.add(lblfirstname);
    jpmain.add(jtffirstname);
    jpmain.add(lbllastname);
    jpmain.add(jtflastname);
    jpmain.add(lblage);
    jpmain.add(jtfage);
    jpmain.add(lblgender);
    jpmain.add(jpradiogender);
    jpmain.add(lblmobphone);
    jpmain.add(jtfmobphone);
    jpmain.add(lblphone);
    jpmain.add(jtfphone);
    jpmain.add(lblstudent);
    jpmain.add(jpradiochoice);
    jpmain.add(lblworkshop);
    jpmain.add(jpcheckboxworkshop);
    jpmain.add(lblhotelroom);
    jpmain.add(listScrollPane);
    jpmain.add(jcbdinner);
    jpmain.add(jbtregister);

    JFrame frame = new JFrame("Conference Registration");
    frame.add(jpmain);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setSize(400,700);
    frame.setVisible(true);
    frame.setLocationRelativeTo(null);
}   

    public static void main(String[] args) {
        RegistrationSystem a = new RegistrationSystem();
    }

}

[Majestics]

Grid Layout set the layout in the form of Rows and columns , there are no options for setting the content size... Better move to Grid Bag Layout, it is the most flexiable one with size and placement options.