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

class JavaGUI extends JFrame{
    String names[] = {"1", "2", "3" ,"+" , "4", "5", "6", "-", "7", "8", "9", "*", "C", "0", "=", "/"};
    JTextField inputText;
    JButton buttons[];

    JavaGUI(){
        setSize(300, 400);
        setTitle("계산기");
        setLayout(new BorderLayout(0, 10));

        JPanel inputPanel = new JPanel(new BorderLayout(5, 2));
        JPanel buttonPanel = new JPanel(new GridLayout(4, 4));

        add(inputPanel, BorderLayout.NORTH);
        add(buttonPanel, BorderLayout.CENTER);


        inputText = new JTextField();
        inputText.setHorizontalAlignment(JTextField.RIGHT);
        inputPanel.add(inputText);
   
        buttons = new JButton[16];
        for(int i = 0; i< 16; i++){
            buttons[i] = new JButton(names[i]);
            buttonPanel.add(buttons[i]);
        }

        setVisible(true);
        setDefaultCloseOperation(EXIT_ON_CLOSE);
    }
}

class Calculator extends JavaGUI implements ActionListener{

    Calculator(){
        for(int i = 0; i< 16; i++){
            buttons[i].addActionListener(this);
        }
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        JButton pressedButton = (JButton)e.getSource();
        String text = pressedButton.getText();

        switch (text) {
            case "=":
                int result = textAnalysis(inputText.getText());
                inputText.setText("" + result);
                break;
            
            case "C":
                inputText.setText("");
                break;
        
            default:
                inputText.setText(inputText.getText() + text);
                break;
        }          
    }

    int textAnalysis(String text){
        if (text.contains("+")){
            String[] formula = text.split("\\+");
            int x = Integer.parseInt(formula[0]);
            int y = Integer.parseInt(formula[1]);
            return x + y;
        }
        if (text.contains("-")){
            String[] formula = text.split("-");
            int x = Integer.parseInt(formula[0]);
            int y = Integer.parseInt(formula[1]);
            return x - y;
        }
        if (text.contains("*")){
            String[] formula = text.split("\\*");
            int x = Integer.parseInt(formula[0]);
            int y = Integer.parseInt(formula[1]);
            return x * y;
        }
        if (text.contains("/")){
            String[] formula = text.split("/");
            int x = Integer.parseInt(formula[0]);
            int y = Integer.parseInt(formula[1]);
            return x / y;
        }
        return 0;
    }
}


public class GUI {
    public static void main(String[] args) {
        System.out.println("시작!");
        Calculator gui = new Calculator();
    }
}