Firstly, I know Lists are better in almost(if not all) every way. I have encountered a substantial bug in an encoder program that I am making. In this program, I have a button that resets the "wheels" responsible for encoding(One of the wheels rotates after every letter encoded). I have a final int[][] called wheelsOriginal that is supposed to store the original value of the int[][] called wheels. Both of these arrays are int[9][36]. I would like a way of making wheelsOriginal stay unchanged throughout the program instead of changing with wheels for some reason. Here is a good way to recreate the problem(Sorry for the lengthy intToChar and charToInt methods!):
Main class:
import java.awt.*;
import javax.swing.*;
public class mainClass {
public static void main(String[] args) {
JFrame frame = new JFrame("Encoder");
frame.setBackground(new Color(225,225,225));
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
Display d = new Display();
frame.add(d);
frame.pack();
frame.setResizable(false);
frame.setVisible(true);
}
}
Display class:
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class Display extends JPanel implements ActionListener {
static JButton button;
static JLabel letter;
static int currentKey = -10;
static int wheel = 0;
static int[][] wheels = {
{-3,10,-6,2,20,-7,22,5,23,4,6,-9,3,26,0,15,21,-2,13,14,12,1,17,11,-8,-5,18,8,24,9,25,7,19,16,-4,-1},
{9,22,14,12,18,-3,3,6,16,1,-7,25,24,19,-8,8,21,20,5,-6,-2,26,15,-9,23,10,11,0,-5,4,-4,2,17,-1,13,7},
{18,20,-9,15,12,-6,16,-4,-5,14,24,-7,-8,-3,-1,1,4,7,8,25,10,11,5,6,13,22,19,21,23,-2,3,26,17,9,0,2},
{-3,10,-6,2,20,-7,22,5,23,4,6,-9,3,26,0,15,21,-2,13,14,12,1,17,11,-8,-5,18,8,24,9,25,7,19,16,-4,-1},
{9,22,14,12,18,-3,3,6,16,1,-7,25,24,19,-8,8,21,20,5,-6,-2,26,15,-9,23,10,11,0,-5,4,-4,2,17,-1,13,7},
{25,18,5,8,7,-8,4,11,6,-7,26,21,-1,24,15,23,9,-6,-2,13,16,22,-5,10,17,3,1,-9,0,12,2,19,-4,14,20,-3},
{25,18,5,8,7,-8,4,11,6,-7,26,21,-1,24,15,23,9,-6,-2,13,16,22,-5,10,17,3,1,-9,0,12,2,19,-4,14,20,-3},
{25,18,5,8,7,-8,4,11,6,-7,26,21,-1,24,15,23,9,-6,-2,13,16,22,-5,10,17,3,1,-9,0,12,2,19,-4,14,20,-3},
{9,22,14,12,18,-3,3,6,16,1,-7,25,24,19,-8,8,21,20,5,-6,-2,26,15,-9,23,10,11,0,-5,4,-4,2,17,-1,13,7}
};
final static int[][] wheelsOriginal = wheels;
public Display() {
setPreferredSize(new Dimension(250,200));
setFocusable(true);
button = new JButton("Reset");
button.setPreferredSize(new Dimension(225,50));
button.setFont(new Font(button.getFont().getFontName(), button.getFont().getStyle(), 25));
letter = new JLabel(" ", SwingConstants.CENTER);
letter.setPreferredSize(new Dimension(225,100));
letter.setFont(new Font(letter.getFont().getFontName(), Font.BOLD, 125));
letter.setForeground(new Color(0,0,0));
addKeyListener(
new KeyListener() {
public void keyPressed(KeyEvent e) {
if(currentKey == -10 && e.getKeyCode() >= 65 && e.getKeyCode() <= 90) {
currentKey = e.getKeyCode() - 64;
letter.setText(encode() + "");
}
else if(currentKey == -10 && e.getKeyCode() >= 48 && e.getKeyCode() <= 57) {
currentKey = -1 * (e.getKeyCode() - 48);
letter.setText(encode() + "");
}
}
public void keyReleased(KeyEvent e) {
currentKey = -10;
letter.setText(" ");
}
public void keyTyped(KeyEvent e) {}
}
);
button.addActionListener(this);
add(button, TOP_ALIGNMENT);
add(letter);
}
public static char encode() {
int key = currentKey;
for(int i = 0; i < 9; i++) {
key = wheels[i][key + 9];
}
for(int i = 8; i >= 0; i--) {
key = wheels[i][key + 9];
}
rotate(wheels[wheel], isEven(wheel));
if(wheel < 8) {
wheel++;
}
else {
wheel = 0;
}
return((char) key);
}
public static int[] rotate(int[] wheel, boolean positive) {
int revolve;
if(positive) {
revolve = wheel[wheel.length - 1];
for(int i = wheel.length - 2; i > 0; i--) {
wheel[i + 1] = wheel[i];
}
wheel[0] = revolve;
}
else {
revolve = wheel[0];
for(int i = 1; i < wheel.length - 1; i++) {
wheel[i - 1] = wheel[i];
}
wheel[wheel.length - 1] = revolve;
}
return wheel;
}
public static boolean isEven(int num) {
return (num/2 == Math.abs(num/2));
}
public void actionPerformed(ActionEvent e) {
if(e.getSource().equals(button)) {
reset();
grabFocus();
}
}
public static void reset() {
for(int[] i : wheels) {
for(int x : i) {
System.out.print(x + " ");
}
System.out.println("");
}
System.out.println(" ");
for(int[] i : wheelsOriginal) {
for(int x : i) {
System.out.print(x + " ");
}
System.out.println("");
}
System.out.println(" ");
wheels = wheelsOriginal;
for(int[] i : wheels) {
for(int x : i) {
System.out.print(x + " ");
}
System.out.println("");
}
wheel = 0;
letter.setText(" ");
currentKey = ' ';
System.out.println("Pressed");
}
}
Whenever a key is pressed, the encoded letter appears in the window. Even pressing the same key over and over again will usually produce different letters. Pressing the reset button should reset the encoder so that pressing the letter 'A' three times should produce S, E, and Q in that order. I also have designed this so that whenever you press the reset button, three large bulks of numbers print in the console. These show the wheels array before reset, the wheelsOriginal array, and the product wheels array in that order. If you press keys and click reset several times, you will notice that wheelsOriginal changes with wheels. Please help...
Your problem is that you are creating wheelsOriginal as reference of wheels instead of copy. Thats why when you change wheels, wheelsOriginal changes as well.
final static int[][] wheelsOriginal = wheels;
Something like this loop can be used to create a copy of wheels
int[][] wheelsOriginal = new int[wheels.length][];
for( int i = 0; i < wheelsOriginal.length; i++ )
{
wheelsOriginal[i] = Arrays.copyOf( wheels[i], wheels[i].length );
}
Also, for your charToInt and IntToChar methods - you could use the fact that chars are numbers and a->z A->Z 0->9 are grouped together to shorten them significantly
I didn't test that - in case you decide to use something like this - think and test yourself
public int charToInt( char c )
{
if( c >= '0' && c <= '9' ) {
return '0' - c;
} else if( c >= 'A' && c <= 'Z' ) {
return c - 'A' + 1;
} else if( c >= 'a' && c <= 'z' ) {
return c - 'a' + 1;
} else {
return -10;
}
}
public char intToChar( int c )
{
if( c >= -9 && c <= 0 ){
return (char)('0' - c);
} else if( c >= 1 && c <= 26 ){
return (char)(c + 'A' - 1);
} else{
return ' ';
}
}