Explain code

Question

code link sololearn
https://code.sololearn.com/cm94iQbqiGF8

Answer 1

Ook no problem

Answer 2

another hidden secret
//decButton.setBounds(150,430,100,50);
delButton.setBounds(150,430,100,50); // rename to delButton

it will show the Delete button

Answer 3

Ohk

Answer 4

there are some errors

import java.awt.*; //for desktop
import java.awt.event.*;
import javax.swing.*;

Main()
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); // not EXIT_ON_CLODE

public void actionPerformed(ActionEvent e) { // not actionperformed

Answer 5

try two calculations without clear button, you get an incorrect result, press:

3+6=
9-6=
3.09
--------
if display is empty and (-) is pressed, it crashes