I noticed this kinda of event some weeks ago, but I ignored, now it's making me curious. the last element that I add always end up in the up position of the screen, no matter how much I try to alter the positions of the elements created, the result is the same.

It was supposed to have two buttons inline.

import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import static javax.swing.WindowConstants.EXIT_ON_CLOSE;
import javax.swing.border.TitledBorder;
public class Todolist extends JFrame{
private JLabel jcriar, jtexto, jnum, jtexto1;
private JButton btcriar, btrem;
private JTextField txtcriar;
private JPanel jp;
int t = 0;
    public static void main(String[] args) {
        JFrame op = new Todolist();
        op.setVisible(true);
        op.setLayout(null);
        op.setSize(500, 400);
        op.setDefaultCloseOperation(EXIT_ON_CLOSE);
    }
    public Todolist(){
        elemen();
    }
    public void elemen(){
    jcriar =  new JLabel("criar/remover");
    txtcriar = new JTextField();
    btcriar = new JButton("criar");
    btrem = new JButton("remover");
    jp = new JPanel();
    jp.setBounds(230, 100, 150, 200);
    jp.setLayout(null);
    jp.setBorder(new TitledBorder(""));
    jcriar.setBounds(30, 30, 100, 20);
    txtcriar.setBounds(131, 30, 100, 20);
    btcriar.setBounds(232, 30, 80, 20);
    btrem.setBounds(314, 30, 80, 20);
    add(jcriar);
    add(txtcriar);
    add(btcriar);
    add(jp);
    add(btrem);
    }
    }
}