Question

I am having some trouble with passing data of an array from one class to the next.

edits
I am now no longer getting the error, and my code compiles, but as I had been warned, I got null for every element of the array. Now that I have taken out the static modifiers though, it still gives me null. I have also updated the code.

Here is the class where the array is created.

public class AssignSeat {

String[] arrangement = new String[12];

public void SeatStart() {

    arrangement[0] = "Collins";
    arrangement[2] = "Faivre";
    arrangement[3] = "Kinnard";
    arrangement[6] = "Morgans";
    arrangement[7] = "Rohan";
    arrangement[8] = "Shatrov";
    arrangement[9] = "Sword";
    arrangement[11] = "Tuckness";

    System.out.format("%-15s%-15s%n", "seat", "passenger");

    for (int i=0; i<arrangement.length; i++) {
        System.out.format("%-15s%-15s%n", i+1, arrangement[i]);

    }

}

public String[] getArrangement() {
    return arrangement;
}

public void setArrangement(String[] arrangement) {
    this.arrangement = arrangement;
}
}

and here is the method trying to access the information. It is specifically the for loop that I need help with so Ignore other areas where there are mistakes. Thank you.

public void actionPerformed(ActionEvent event) {
    Scanner scanner = new Scanner(System.in);
    AssignSeat seat = new AssignSeat();

    if(event.getSource() instanceof JButton){

        JButton clickedButton = (JButton) event.getSource();
        String buttonText = clickedButton.getText();

        if (buttonText.equals("first class")) {
            entername.setVisible(true);
            seatnum.setVisible(true);
            confirmed.setVisible(true);
            inputline.setVisible(true);
            outputline.setVisible(true);
            if ((seat.arrangement[1] == null)) {
                System.out.println(seat.arrangement[0]);
                System.out.println(seat.arrangement[2]);
                two.setForeground(Color.green);
            }
        } else if (buttonText.equals("coach")) {
            //System.out.println("so does this!");
            entername.setVisible(true);
            seatnum.setVisible(true);
            confirmed.setVisible(true);
            inputline.setVisible(true);
            outputline.setVisible(true);
            if ((seat.arrangement[4] == null)) {
                five.setForeground(Color.green);
            } 
            if ((seat.arrangement[5] == null)) {
                six.setForeground(Color.green);
            } 
            if ((seat.arrangement[10] == null)) {
                eleven.setForeground(Color.green);
            } 
        }
    }

}

Answer 1

The problem lies in the fact that the array was declared as static, but the initialization code for it is in the constructor. Remove all the static modifiers in the original code, and replace this part:

if (AssignSeat.getArrangement()[1].equals("null"))

With this:

AssignSeat assign = new AssignSeat();
if (assign.getArrangement()[1] == null)

Also notice that "null" is not a null value, use null (without quotes) for that.

A different approach would be to leave the array as an static member, but initialize it statically, like this:

private static String[] arrangement = new String[12];
static {
    arrangement[0] = "Collins";
    arrangement[2] = "Faivre";
    arrangement[3] = "Kinnard";
    arrangement[6] = "Morgans";
    arrangement[7] = "Rohan";
    arrangement[8] = "Shatrov";
    arrangement[9] = "Sword";
    arrangement[11] = "Tuckness";
}

In that case, this would work:

if (AssignSeat.getArrangement()[1] == null)

But I still believe that making the array static is going to be problematic if several instances of the class happen to be modifying its contents.