import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.GridBagConstraints;
import java.awt.GridLayout;
import java.awt.TextArea;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;

public class Window{

    static int i;
    JButton buttons;

    public static void main(String args[]){

    JFrame frame = new JFrame("Calculator");
    frame.setVisible(true);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setResizable(false);

    TextArea text = new TextArea(2,25);
    text.setEditable(false);

    JPanel gui = new JPanel(new BorderLayout(5,5));
    frame.setContentPane(gui);
    gui.add(text, BorderLayout.NORTH);
    JPanel panelButtons = new JPanel(new GridLayout(3,0,3,3));

    JPanel buttonPanel = new JPanel();
    buttonPanel.setVisible(true);
    buttonPanel.setPreferredSize(new Dimension(150,200));
    frame.getContentPane().add(buttonPanel);

    Font font = new Font("SansSerif", Font.PLAIN, 30);

    JButton[] buttons = new JButton[10];

    for(i=0; i<buttons.length; i++){
        buttons[i] = new JButton(String.valueOf(i));

        buttons[i].setFont(font);
    }

    JButton plusButton = new JButton("+");
    JButton minusButton = new JButton("-");
    JButton equalsButton = new JButton("=");
    JButton clearButton = new JButton("C");

    ActionListener listener = new ActionListener() {

    public void actionPerformed(ActionEvent e) {

    JButton source = (JButton) e.getSource();

    if(source.getText().equals("1")) {
       text.append("1");
    }
    if(source.getText().equals("2")) {
        text.append("2");
     }
    if(source.getText().equals("3")) {
        text.append("3");
     }
    if(source.getText().equals("4")) {
        text.append("4");
     }
    if(source.getText().equals("0")) {
        text.append("0");
     }
    if(source.getText().equals("5")) {
        text.append("5");
     }
    if(source.getText().equals("6")){
        text.append("6");
    }
    if(source.getText().equals("7")){
        text.append("7");
    }
    if(source.getText().equals("8")){
        text.append("8");
    }
    if(source.getText().equals("9")){
        text.append("9");
    }
    if(source.getText().equals("+")){
        text.append("+");
    }
    if(source.getText().equals("-")){
        text.append("-");
    }
    if(source.getText().equals("C")){
        text.setText(" ");
    }
    if(source.getText().equals("=")){
        String textStuff = text.getText();
        if(textStuff.contains("-")){
            String[] parts = textStuff.split("-");
            String part1 = parts[0];
            String part2 = parts[1];
            double num1 = Double.parseDouble(parts[0]);
            double num2 = Double.parseDouble(parts[1]);
            double total = (num1 - num2);
            String finalNum = Double.toString(total);
            text.setText(finalNum);
        }else{
            String[] parts = textStuff.split("[+]");
            String part1 = parts[0];
            String part2 = parts[1];
            double num1 = Double.parseDouble(parts[0]);
            double num2 = Double.parseDouble(parts[1]);
            double total = (num1 + num2);
            String finalNum = Double.toString(total);
            text.setText(finalNum);
        }

    }
    }

    };

    for(i=0; i<buttons.length; i++){
            buttons[i].addActionListener(listener);
        }

     minusButton.addActionListener(listener);
     plusButton.addActionListener(listener);
     equalsButton.addActionListener(listener);
     clearButton.addActionListener(listener);


    GridBagConstraints c = new GridBagConstraints();

    for(i=0; i<buttons.length; i++){
            panelButtons.add(buttons[i], c);
        }

     panelButtons.add(minusButton);
     panelButtons.add(plusButton);
     panelButtons.add(equalsButton);
     panelButtons.add(clearButton);

     gui.add(panelButtons, BorderLayout.CENTER);
     frame.pack();



}
}