teaching machines

CS 245 Lecture 4 – Calculator

September 12, 2013 by Chris Johnson. Filed under cs245, fall 2013, lectures.

Agenda

• specchecker example
• calculator free-for-all

TODO

• Work on preassignment 1. No 1/4 sheet.

Code

CalculatorGUI.java

package lecture0912;

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

public class CalculatorGUI {

  public static void main(String[] args) {
    JFrame frame = new JFrame();
    frame.setVisible(true);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    frame.setSize(700, 500);

    // Panel
    JPanel panel = new JPanel();
    frame.add(panel, BorderLayout.CENTER);

    panel.setLayout(new GridLayout(0, 3));

    // Label
    final JLabel numberDisplay = new JLabel();
    frame.add(numberDisplay, BorderLayout.NORTH);
    numberDisplay.setText("CALCULATOR");
    numberDisplay.setFont(new Font(Font.SANS_SERIF, Font.PLAIN, 36));
    numberDisplay.setHorizontalAlignment(JLabel.RIGHT);

    JButton[] buttons = new JButton[20];
    for (int i = 0; i < buttons.length; i++) {
      buttons[i] = new JButton();
      panel.add(buttons[i]);
    }
    for (int i = 0; i < 10; i++) {
      buttons[i].setText("" + i);
    }
    buttons[10].setText("+");
    buttons[11].setText("-");
    buttons[12].setText("*");
    buttons[13].setText("/");
    buttons[14].setText("=");
    buttons[15].setText(".");
    buttons[19].setText("Clr");

    class ClearListener implements ActionListener {
      @Override
      public void actionPerformed(ActionEvent e) {
        numberDisplay.setText("0");
      }
    }
    buttons[19].addActionListener(new ClearListener());
  }
}

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