What 'no such child' means in java swing when trying to makeCompactGrid with class SpringUtilities

So I tried to make a simple java swing program, i didn't finish the program but I wanted to see how it looks before doing the functionality part, this is my code:

import layouts.SpringUtilities;

import javax.swing.*;
import layouts.SpringUtilities;


public class FactorialCalculatorFrame extends JFrame {

    public FactorialCalculatorFrame(){
        JPanel panel = new JPanel();
        panel.setLayout(new SpringLayout());


        JTextField brojText = new JTextField();
        brojText.setColumns(10);
        panel.add(new JLabel("Broj:", SwingConstants.RIGHT));
        panel.add(brojText);


        JButton start = new JButton("Start");

        panel.add(new JLabel("Pokreni izracun:",SwingConstants.RIGHT));
        panel.add(start);


        JProgressBar napredakProgressBar = new JProgressBar();

        add(new JLabel("Napredak:", SwingConstants.RIGHT));
        add(napredakProgressBar);

        JLabel rezultat = new JLabel("Rezultat:");
        JLabel ispisiRez = new JLabel("");

        add(new JLabel("Rezultat:", SwingConstants.RIGHT));
        add(ispisiRez);


        start.addActionListener((e)->{
            try {
                int number = Integer.parseInt(brojText.getText());

                //reset GUI components
                napredakProgressBar.setValue(0);
                start.setEnabled(false);
                ispisiRez.setText("");

                //schedule for execution on one of working threads
                new primeNumberJavaSwingApp().execute();

                            } catch (Exception ex) {
                ex.printStackTrace();
            }
        });

        SpringUtilities.makeCompactGrid(panel,4, 2, 0, 0, 5, 5);

        add(panel);
    }
    public static void main(String[] args){
        FactorialCalculatorFrame frame = new FactorialCalculatorFrame();
        frame.setVisible(true);
    }

    public class primeNumberJavaSwingApp extends SwingWorker<Long, Integer> {
        @Override
        protected Long doInBackground() throws Exception {
            Long l = (long)3.2;
return l;}}}

the Exception that occurs is this Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: No such child: 4
at layouts.SpringUtilities.makeCompactGrid(SpringUtilities.java:190)
at FactorialCalculatorFrame.<init>(FactorialCalculatorFrame.java:55)

Why does this occurs, what did I do wrong?

I also use SpringUtilities class that I copied from Oracle. Any help is greatly appriciated!

I downloaded source code for class SpringUtilities from here.

Your problem is that you are not adding all the components to the panel. You are calling add() when you should be calling panel.add(). Hence you are only adding 4 components to panel rather than 8. Hence the error message.

I also added a call to method pack(), of class JFrame, in order to make the JFrame big enough to display all the components it contains.

Here is your code with my fixes:

import layout.SpringUtilities; // in your code this import is added twice

import javax.swing.*;

public class FactorialCalculatorFrame extends JFrame {
    public FactorialCalculatorFrame() {
        setDefaultCloseOperation(EXIT_ON_CLOSE); // I added this line
        JPanel panel = new JPanel();
        panel.setLayout(new SpringLayout());

        JTextField brojText = new JTextField();
        brojText.setColumns(10);
        panel.add(new JLabel("Broj:", SwingConstants.RIGHT));
        panel.add(brojText);

        JButton start = new JButton("Start");

        panel.add(new JLabel("Pokreni izracun:",SwingConstants.RIGHT));
        panel.add(start);

        JProgressBar napredakProgressBar = new JProgressBar();

        panel.add(new JLabel("Napredak:", SwingConstants.RIGHT)); // change here
        panel.add(napredakProgressBar); // change here

        JLabel rezultat = new JLabel("Rezultat:");
        JLabel ispisiRez = new JLabel("");

        panel.add(new JLabel("Rezultat:", SwingConstants.RIGHT));
        panel.add(ispisiRez);

        start.addActionListener((e)->{
            try {
                int number = Integer.parseInt(brojText.getText());

                //reset GUI components
                napredakProgressBar.setValue(0);
                start.setEnabled(false);
                ispisiRez.setText("");

                //schedule for execution on one of working threads
                new primeNumberJavaSwingApp().execute();

                            } catch (Exception ex) {
                ex.printStackTrace();
            }
        });
        SpringUtilities.makeCompactGrid(panel, 4, 2, 0, 0, 5, 5);
        add(panel);
    }

    public static void main(String[] args){
        FactorialCalculatorFrame frame = new FactorialCalculatorFrame();
        frame.pack(); // I added this line
        frame.setLocationRelativeTo(null); // I added this line
        frame.setVisible(true);
    }

    public class primeNumberJavaSwingApp extends SwingWorker<Long, Integer> {
        @Override
        protected Long doInBackground() throws Exception {
            Long l = (long) 3.2;
            return l;
        }
    }
}

Here is a screen capture of the JFrame when running the above code.