DIY simple calculator

Draw lessons from bloggers https://blog.csdn.net/without_scruple/article/details/78603605
This blogger's code is the most easy to understand and concise code I see. At the same time, I added the functions of clearing, naming and icon to realize simple addition, subtraction, multiplication and division
A closer understanding of the java interface
The code is as follows:

package design;

import java.awt.BorderLayout;
import java.awt.GridLayout;
import java.awt.Panel;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.StreamTokenizer;
import java.util.StringTokenizer;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;



public class Demo1_topic01 extends JFrame {

	private static final long serialVersionUID = 1L;
	private JTextField text;
	public JButton jb0,jb1,jb2,jb3,jb4,jb5,jb6,jb7,jb8,jb9;	//Four numbers from 0 to 9 (can be written as an array)
	public JButton bot,add,sub,mul,div,equ,clear;	//Addition, subtraction, multiplication and division, and five symbols of decimal point
	private JPanel panel;
	
	public Demo1_topic01() {
		init();
		Panel();
		MyEvent();	//event processing
	}

	private void MyEvent() {
		//Add event handling for each button
		Text(jb0);
		Text(jb1);
		Text(jb2);
		Text(jb3);
		Text(jb4);
		Text(jb5);
		Text(jb6);
		Text(jb7);
		Text(jb8);
		Text(jb9);
		Text(bot);
		Text(add);
		Text(sub);
		Text(mul);
		Text(div);
		
		//Event handling of "=" button
		equ.addActionListener(new ActionListener() {
			
			@Override
			public void actionPerformed(ActionEvent arg0) {
				text.setText(text.getText() + equ.getText());
				if(text.getText().contains("+")) {//Do addition
					StringTokenizer str1 = new StringTokenizer(text.getText(), "+");
					double d1, d2 = 0;
					d1 = Double.parseDouble(str1.nextToken());
					while (str1.hasMoreTokens()) {
						StringTokenizer str2 = new StringTokenizer(str1.nextToken(),"=");
						d2 = Double.parseDouble(str2.nextToken());
					}
					text.setText(text.getText() + " " + (d1+d2));//Put the result in the text area
				}else if (text.getText().contains("-")) {
					StringTokenizer str1 = new StringTokenizer(text.getText(),"-");
					double d1,d2 = 0;
					d1 = Double.parseDouble(str1.nextToken());
					while(str1.hasMoreTokens()){
						StringTokenizer str2 = new StringTokenizer(str1.nextToken(),"=");
						d2 = Double.parseDouble(str2.nextToken());
					}
					text.setText(text.getText() + " " + (d1-d2));
				}else if(text.getText().contains("*")) {
					StringTokenizer str1 = new StringTokenizer(text.getText(),"*");
					double d1,d2 = 0;
					d1 = Double.parseDouble(str1.nextToken());
					while(str1.hasMoreTokens()){
						StringTokenizer str2 = new StringTokenizer(str1.nextToken(),"=");
						d2 = Double.parseDouble(str2.nextToken());
					}
					text.setText(text.getText() + " " + (d1*d2));
				}else if (text.getText().contains("/")){
					StringTokenizer str1 = new StringTokenizer(text.getText(),"/");
					double d1,d2 = 0;
					d1 = Double.parseDouble(str1.nextToken());
					while(str1.hasMoreTokens()){
						StringTokenizer str2 = new StringTokenizer(str1.nextToken(),"=");
						d2 = Double.parseDouble(str2.nextToken());
					}
					text.setText(text.getText() + " " + (d1/d2));
				}
			}
		});
		
		clear.addActionListener(new ActionListener() {
			
			@Override
			public void actionPerformed(ActionEvent arg0) {
				text.setText("");
			}
		});
		
		
	}

	private void Text(final JButton button) {//Event handling method of each button
		button.addActionListener(new ActionListener() {
			
			@Override
			public void actionPerformed(ActionEvent arg0) {
				String str = button.getText();
				text.setText(text.getText() + str);
			}
		});
	}

	private void Panel() {
		panel = new JPanel();		//New calculator number and symbol area panel
		panel.setLayout(new GridLayout(4,4));	//Set panel layout
		//Place the button components in the panel
		//first line
		panel.add(jb7);
		panel.add(jb8);
		panel.add(jb9);
		panel.add(div);
		//Second elements
		panel.add(jb4);
		panel.add(jb5);
		panel.add(jb6);
		panel.add(mul);
		//Third elements
		panel.add(jb1);
		panel.add(jb2);
		panel.add(jb3);
		panel.add(sub);
		//Fourth elements
		panel.add(bot);
		panel.add(jb0);
		panel.add(equ);
		panel.add(add);
		
		//panel.add(clear);
		
		
		this.add(panel,BorderLayout.CENTER);
		
		Panel sourth  = new Panel();
		sourth.add(clear);
		this.add(sourth,BorderLayout.SOUTH);//Place the Panel to the south of the Frame
	}

	private void init() {
		this.setBounds(800, 300, 400, 400);	//Form size
		this.setTitle("WhitestのCabbage - simple calculator");			//Form name
		this.setLayout(new BorderLayout());
		text = new JTextField(30);			//Computation area
		this.add(text,BorderLayout.NORTH);
		//New number button
		jb0 = new JButton("0");
		jb1 = new JButton("1");
		jb2 = new JButton("2");
		jb3 = new JButton("3");
		jb4 = new JButton("4");
		jb5 = new JButton("5");
		jb6 = new JButton("6");
		jb7 = new JButton("7");
		jb8 = new JButton("8");
		jb9 = new JButton("9");
		
		//New symbol button
		bot = new JButton(".");
		add = new JButton("+");
		sub = new JButton("-");
		mul = new JButton("*");
		div = new JButton("/");
		equ = new JButton("=");
		clear = new JButton("C");
		
		this.setIconImage(Toolkit.getDefaultToolkit().createImage("Calculator.png"));
		
		
		this.setVisible(true);			//Set form display
	}
	public static void main(String[] args) {
		new Demo1_topic01();
	}

}

Operation interface