Adding panel to scrollpane on button click

Question

Please run the below code with
javac MyTestingNew.java and
java MyTestingNew
I am having a button(ADD ME) on click of that I want to add panel containg textfield
which will append to already exist textfields which are diasplyed in jscrollpane
How I can proceed??
import javax.swing.*;
import java.awt.Dimension;
import java.awt.event.*;
class MyTestingNew extends JFrame{
     static Sale2 sale2;
     static int coordinate = 0;
     final int SIZE = 5;
       JPanel[] jp = new JPanel[20];
   //     ButtonGroup[] group = new ButtonGroup[SIZE]; 
   //     JRadioButton[] rb = new JRadioButton[SIZE * SIZE];
     JTextField[] jtf = new JTextField[SIZE * 1000];
     JButton jb = new JButton();
        public MyTestingNew(){
             buildGUI(); 
    public void buildGUI(){   
         setSize(1200,800);   
         //setLocation(400,300);  
          setDefaultCloseOperation(EXIT_ON_CLOSE);  
          JPanel main = new JPanel();
         //JPanel main = new JPanel(new GridLayout(20,1));
         main.setLayout(null);
         jb.setText("ADD ME");
         jb.setBounds(0,0,100,30);
         sale2=new Sale2(this);
         jb.addActionListener(sale2);
         main.setPreferredSize(new Dimension(353,800));
         //main.setBounds(420,335,353,381);
         //main.setBounds(0,0,353,381);
         for(int x = 0; x <20; x++){
               //group[x] = new ButtonGroup();    
            jp[x] = new JPanel();
                //jp[x] = new JPanel(new GridLayout(1,SIZE));
              jp[x].setLayout(null);
              jp[x].setBounds(0,coordinate,353,32);
              //jp[x].setBounds(0,coordinate,353,32);
                System.out.println("SIZE  :"+ SIZE);
            jp[x].setBorder(BorderFactory.createEtchedBorder());   
            for(int y = 1; y < SIZE+1; y++){
                 int rbNum = x*SIZE + y;
                 System.out.println("X : "+x+ "Y : "+y+" rbNum : "+rbNum);
                 if(y==1) {jtf[rbNum] = new JTextField(""+rbNum);jtf[rbNum].setBounds(0,0,30,32);}
                 if(y==2) {jtf[rbNum] = new JTextField(""+rbNum);jtf[rbNum].setBounds(32,0,180,32);}
                 if(y==3) {jtf[rbNum] = new JTextField(""+rbNum);jtf[rbNum].setBounds(214,0,35,32);}
                 if(y==4) {jtf[rbNum] = new JTextField(""+rbNum);jtf[rbNum].setBounds(251,0,35,32);}
                 if(y==5) {jtf[rbNum] = new JTextField(""+rbNum);jtf[rbNum].setBounds(288,0,65,32);}
                jp[x].add(jtf[rbNum]);  
                 coordinate = coordinate + 7;
            main.add(jp[x]);   
        JScrollPane sp = new JScrollPane(main);
         //sp.setVerticalScrollBarPolicy(javax.swing.JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
         sp.setBounds(420,335,353,350);
         JPanel main2 = new JPanel();
         main2.setLayout(null);
         //main2.setPreferredSize(new Dimension(400,400));
         main2.add(sp);
         main2.add(jb);
         getContentPane().add(main2);
       public static void main(String[] args){
               new MyTestingNew().setVisible(true);
class Sale2 implements ActionListener
MyTestingNew parent;
Sale2(MyTestingNew parent)
this.parent=parent;
public void actionPerformed(ActionEvent e)
     //My code will come here
     System.out.println("get from button");
}

Answer 1

You really should start learning how to use LayoutManagers.. they make life a lot easier
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
class MyTestingNew extends JFrame {
    final int SIZE = 5;
    JPanel[] jp = new JPanel[20];
    JTextField[] jtf = new JTextField[SIZE * 1000];
    JButton jb = new JButton();
    private int nrOfRows = 20;//starting nr of rows
    public MyTestingNew() {
        buildGUI();
    public void buildGUI() {
        setTitle("My Test");
        setSize(1200, 800);
        //setLocation(400,300);
        setDefaultCloseOperation(EXIT_ON_CLOSE);
        final JPanel main = new JPanel();
        //JPanel main = new JPanel(new GridLayout(20,1));
        main.setLayout(new BoxLayout(main,BoxLayout.Y_AXIS));
        jb.setText("ADD ME");
        jb.setBounds(0, 0, 100, 30);
        jb.addActionListener(new ActionListener(){
            public void actionPerformed(ActionEvent evt){
                JPanel newPanel = new JPanel();
                newPanel.setLayout(new GridLayout(1,SIZE));
                for (int y = 1; y < SIZE + 1; y++) {
                    int rbNum = nrOfRows * SIZE + y;
                    System.out.println("X : " + nrOfRows + " Y : " + y + " rbNum : " + rbNum);
                    newPanel.add(new JTextField("" + rbNum));
                main.add(newPanel);
                main.revalidate();
                nrOfRows++;//added a new row
        for (int x = 0; x < nrOfRows; x++) {
            jp[x] = new JPanel();
            jp[x].setLayout(new GridLayout(1,SIZE));
            System.out.println("SIZE  :" + SIZE);
            for (int y = 1; y < SIZE + 1; y++) {
                int rbNum = x * SIZE + y;
                System.out.println("X : " + x + " Y : " + y + " rbNum : " + rbNum);
                jtf[rbNum] = new JTextField("" + rbNum);
                jp[x].add(jtf[rbNum]);
            main.add(jp[x]);
        JScrollPane sp = new JScrollPane(main);
        //sp.setVerticalScrollBarPolicy(javax.swing.JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
        sp.setBounds(420, 335, 353, 350);
        JPanel main2 = new JPanel();
        main2.setLayout(null);
        //main2.setPreferredSize(new Dimension(400,400));
        main2.add(sp);
        main2.add(jb);
        getContentPane().add(main2);
    public static void main(String[] args) {
        new MyTestingNew().setVisible(true);
}