BinCalc.java

/*
    BinCalc.java
    CIS 260
    2006-03-01
    David Klick

Demonstration of creating a GUI component using
    other Swing components.
*/

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

class BinCalc extends JPanel {
    private JTextField txt;
    private JButton[] btn = new JButton[4];

public BinCalc() {
        // set up panels and layouts
        setLayout(new GridLayout(2, 1, 10, 10));
        JPanel pnlTop = new JPanel();
        JPanel pnlBottom = new JPanel();
        pnlTop.setLayout(new BorderLayout());
        pnlBottom.setLayout(new GridLayout(1, 4, 10, 5));

// create buttons
        btn[0] = new JButton("0");
        btn[1] = new JButton("1");
        btn[2] = new JButton("Clear");
        btn[3] = new JButton("Calc");

// change button 2's font
        Font f = new Font("Comic Sans MS", Font.ITALIC, 12);
      
        // add buttons
        for (int i=0; i<4; i++) pnlBottom.add(btn[i]);

// create and add text display
        txt = new JTextField(20);
        txt.setText("");
        txt.setEditable(false);
        pnlTop.add(txt);

add(pnlTop);
        add(pnlBottom);
    }

public void clear() { txt.setText(""); }
    public String getText() { return txt.getText(); }
    public void setText(String s) {
        clear();
        append(s);
    }
    public void append(String s) {
        for (int i=0; i<s.length(); i++) append(s.charAt(i));
    }
    public void append(char c) {
        if (c=='0' || c=='1') txt.setText(txt.getText() + c);
    }
    public void addActionListener(ActionListener lst) {
        for (int i=0; i<4; i++) btn[i].addActionListener(lst);
    }
}