I want to implement more Advance features to my java simple Calculator

Question

I build a simple calculator using java and now i want to add more advance features where i will be able to add more operands and operators at a time..
like my own simple calculator is to handle two numbers at once like 2+2=4 but i want something more sophisticated like unlimited operands and different operators too like 2+6*5/2= ? in one line.. Please help me out!!

***This is my former code:***

import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
import java.awt.Font;
import java.awt.font.*;

public class Gui implements ActionListener {

JTextField screen;
JButton off, b0, b1, b2, b3, b4, b5, b6, b7, b8, b9, bPoint, bClear, divideBtn, minusBtn, plusBtn,multiplyBtn, btn;
String s0, s1, s2;

public Gui(){
// set them into empty string
s0 = s1 = s2 = "";

JFrame frame= new JFrame();
JPanel mainPanel= new JPanel(new BorderLayout());
JPanel btnPanel= new JPanel(new GridLayout(6,5));
Font font1 = new Font("Digital-7 Italic", Font.BOLD, 24);

// create number buttons
b0 = new JButton("0");
b1 = new JButton("1");
b2 = new JButton("2");
b3 = new JButton("3");
b4 = new JButton("4");
b5 = new JButton("5");
b6 = new JButton("6");
b7 = new JButton("7");
b8 = new JButton("8");
b9 = new JButton("9");
bClear = new JButton("C");
divideBtn = new JButton("/");
minusBtn = new JButton("-");
plusBtn = new JButton("+");
multiplyBtn = new JButton("x");
btn = new JButton("=");
// create . button
bPoint = new JButton(".");
off = new JButton("OFF");

// Setting attribute for frame object
frame.setTitle("Calculator");
frame.setSize(380, 400);
frame.setResizable(true);

screen=new JTextField("0");
screen.setFont(font1);
screen.setEditable(false);
screen.setHorizontalAlignment(SwingConstants.RIGHT);
screen.setPreferredSize(new Dimension(100, 70));

// Add component on panel
btnPanel.add(off);
btnPanel.add(screen);
btnPa

Answer 1

Don't know if this is still relevant. It's hard to help with gui codes on SoloLearn as they don't run on the playground.

Answer 2

The class PowerCalculater can manage one line expressions like:
3 *(4+75/5)- (4-23%7)/2
((3+43)*(32-11) + 21)*(34-21)

https://code.sololearn.com/cicAa55y1lSw/?ref=app