Question

This is the “main” class (doesn’t contain the main method)

import javax.swing.*;
import java.awt.*;
//import java.lang.Object;
//import java.awt.event.ActionListener;
//import java.awt.event.;

public class Program {

  public JFrame frame;
  public JPanel header;
  public JPanel text;
  public JPanel body;
  public JTextField input;
  public JButton agregar;

  public List listA;
  public List listB;

  public Program(String title) {
    frame = new JFrame(title);
    frame.setSize(500,600);
    frame.setResizable(false);
    frame.setVisible(true);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setLayout(null);

    header = new JPanel();
    header.setBackground(new Color(255,204,50));
    header.setBounds(0,0,500,100);

    text = new JPanel();
    text.setBackground(new Color(255,204,100));
    text.setBounds(0,100,500,50);
    text.setLayout(null);

    //Inicializando la "entrada"
    input = new JTextField(20);
    input.setBounds(50,13,300,25);
    text.add(input);

    agregar = new JButton();
    agregar.setBounds(360,12,80,25);
    agregar.setText("Agregar");
    text.add(agregar);
    //Listo

    body = new JPanel();
    body.setBackground(new Color(255,204,150));
    body.setBounds(0,150,500,450);

    //Lo que está dentro del body
    listA = new List(20);
    body.add(listA);

    listB = new List(20);
    body.add(listB);
    //Listo

    //Añadir todos los paneles al frame principal
    frame.add(header);
    frame.add(text);
    frame.add(body);

  }
}

And this is the MAIN class (This one contains the main method):

public class Main {
  public static void main(String[] args) {
    new Program("Ordenamiento Recursivo");
  }
}

Each time I run the application, the UI components are presented differently, please see attached screen shot.

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Well, thanks to everyone who responded the post, I finished the program and I’m very happy with the final result, here it is:

In case anyone wants to take a look at the code, here it is: Link

Answer 1

Problems:

• You’re call setVisible(true) on your JFrame before adding components and this will lead to unreliable drawing of your program’s graphics and is why you are seeing different results. Don’t do this, but rather call it after you’ve added all to the top-level Window.
• As the others are saying, read up and learn to use the layout managers.