Showing a 2D array in a JTable in Java

Question

I have 2 classes, WordSearch.java is where all the main code is held and WordSearchSwing.java is where I wish to create a JTable to display the 2D array "letters". The JTable doesn't display any content (just 12 blank cells) when the following code is run. I cannot figure out why it will not work, any help would be much appreciated.

WordSearch Class:

import java.util.ArrayList;

public class WordSearch {

    public static String[][] letters = new String[12][12];
    static ArrayList<String> words = new ArrayList<String>();

    public static void main(String[] args) {


        //populating the arrayList with Strings, some which are in the wordsearch and some which aren't
        words.add("ghost");     words.add("knife");     words.add("patch");     words.add("ghoul");     words.add("apple");
        words.add("boo");       words.add("spider");    words.add("pumpkin");   words.add("house");     words.add("trick");
        words.add("cat");       words.add("candy");     words.add("orange");    words.add("rat");       words.add("crow");
        words.add("blood");     words.add("bats");      words.add("neck");      words.add("mask");      words.add("witch");
        words.add("party");     words.add("broom");     words.add("fangs");     words.add("mummy"); 

        //A 2D array is used to make the wordsearch
        //Here each coordinate is assigned a letter
        letters[0][0] = "o";    letters[1][0] = "e";    letters[2][0] = "o";    letters[3][0] = "e";    letters[4][0] = "b";    letters[5][0] = "o";
        letters[0][1] = "h";    letters[1][1] = "n";    letters[2][1] = "i";    letters[3][1] = "l";    letters[4][1] = "t";    letters[5][1] = "r";
        letters[0][2] = "b";    letters[1][2] = "c";    letters[2][2] = "o";    letters[3][2] = "d";    letters[4][2] = "y";    letters[5][2] = "a";
        letters[0][3] = "d";    letters[1][3] = "o";    letters[2][3] = "t";    letters[3][3] = "m";    letters[4][3] = "d";    letters[5][3] = "n";
        letters[0][4] = "d";    letters[1][4] = "h";    letters[2][4] = "m";    letters[3][4] = "a";    letters[4][4] = "c";    letters[5][4] = "g";
        letters[0][5] = "p";    letters[1][5] = "u";    letters[2][5] = "o";    letters[3][5] = "a";    letters[4][5] = "p";    letters[5][5] = "e";
        letters[0][6] = "m";    letters[1][6] = "u";    letters[2][6] = "n";    letters[3][6] = "u";    letters[4][6] = "t";    letters[5][6] = "r";
        letters[0][7] = "m";    letters[1][7] = "d";    letters[2][7] = "m";    letters[3][7] = "k";    letters[4][7] = "s";    letters[5][7] = "e";
        letters[0][8] = "y";    letters[1][8] = "d";    letters[2][8] = "c";    letters[3][8] = "p";    letters[4][8] = "h";    letters[5][8] = "e";
        letters[0][9] = "w";    letters[1][9] = "e";    letters[2][9] = "i";    letters[3][9] = "e";    letters[4][9] = "k";    letters[5][9] = "r";
        letters[0][10] = "n";   letters[1][10] = "y";   letters[2][10] = "n";   letters[3][10] = "e";   letters[4][10] = "o";   letters[5][10] = "i";
        letters[0][11] = "c";   letters[1][11] = "t";   letters[2][11] = "f";   letters[3][11] = "h";   letters[4][11] = "o";   letters[5][11] = "w";

        letters[6][0] = "b";    letters[7][0] = "o";    letters[8][0] = "o";    letters[9][0] = "l";    letters[10][0] = "c";   letters[11][0] = "h";
        letters[6][1] = "o";    letters[7][1] = "b";    letters[8][1] = "h";    letters[9][1] = "t";    letters[10][1] = "a";   letters[11][1] = "s";
        letters[6][2] = "g";    letters[7][2] = "h";    letters[8][2] = "o";    letters[9][2] = "s";    letters[10][2] = "t";   letters[11][2] = "g";
        letters[6][3] = "r";    letters[7][3] = "b";    letters[8][3] = "a";    letters[9][3] = "t";    letters[10][3] = "s";   letters[11][3] = "n";
        letters[6][4] = "e";    letters[7][4] = "o";    letters[8][4] = "f";    letters[9][4] = "u";    letters[10][4] = "t";   letters[11][4] = "a";
        letters[6][5] = "d";    letters[7][5] = "e";    letters[8][5] = "f";    letters[9][5] = "t";    letters[10][5] = "m";   letters[11][5] = "f";
        letters[6][6] = "i";    letters[7][6] = "c";    letters[8][6] = "k";    letters[9][6] = "o";    letters[10][6] = "p";   letters[11][6] = "m";
        letters[6][7] = "p";    letters[7][7] = "h";    letters[8][7] = "o";    letters[9][7] = "e";    letters[10][7] = "a";   letters[11][7] = "a";
        letters[6][8] = "s";    letters[7][8] = "r";    letters[8][8] = "c";    letters[9][8] = "l";    letters[10][8] = "r";   letters[11][8] = "s";
        letters[6][9] = "b";    letters[7][9] = "r";    letters[8][9] = "d";    letters[9][9] = "p";    letters[10][9] = "t";   letters[11][9] = "k";
        letters[6][10] = "o";   letters[7][10] = "o";   letters[8][10] = "e";   letters[9][10] = "p";   letters[10][10] = "y";  letters[11][10] = "e";
        letters[6][11] = "n";   letters[7][11] = "l";   letters[8][11] = "u";   letters[9][11] = "a";   letters[10][11] = "a";  letters[11][11] = "s";


        //searchAcross();
        //searchDown();
    }

    //A method used to search across the grid for words
    public static void searchAcross(){
        for (int i =0; i < 12; i++) {
            for (int j = 0; j < 12; j++) {
                for (int k = 0; k < words.size(); k++){
                    if (words.get(k).contains(letters[i][j]) && (words.get(k).contains(letters[i][j+1])) && (words.get(k).contains(letters[i][j+2]))){
                        System.out.println(words.get(k));
                        }
                    }
                }
            }
        }

    // A method used to search down the grid for words
    public static void searchDown(){
        for (int j =0; j < 12; j++) {
            for (int i = 0; i < 12; i++) {
                for (int k = 0; k < words.size(); k++){
                    if (words.get(k).contains(letters[j][i]) && (words.get(k).contains(letters[j][i+1])) && (words.get(k).contains(letters[j][i+2]))){
                        System.out.println(words.get(k));
                        }
                    }
                }
            }
    }
}

WordSearchSwing Class:

import javax.swing.*;
public class WordSearchSwing {

    private JPanel contentPane;
    private JTable table;

    /**
     * Launch the application.
     */
    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            public void run() {
                try {
                    WordSearchSwing frame = new WordSearchSwing();
                    frame.setVisible(true);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
    }

    /**
     * Create the frame.
     */
    public WordSearchSwing() {
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setBounds(100, 100, 450, 300);
        contentPane = new JPanel();
        contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
        contentPane.setLayout(new BorderLayout(0, 0));
        setContentPane(contentPane);

        Object[] title = {"Happy Halloween"};
        table = new JTable(WordSearch.letters, title);
        contentPane.add(table, BorderLayout.CENTER);
    }

}

Answer 1

To expand on @Hakan's answer:

When you run your code, it'll start by running one (and only one) main method. So if you see the GUI, it ran the main method of WordSearchSwing . This means that the main method of WordSearch was not run.

The easiest (but definitely not the best) way to fix this is to add WordSearch.main(new String[]{}); before you create the JTable.

What it looks like you're trying to use for WordSearch in this instance is a Singleton pattern . This would be a much better solution than the above.

Answer 2

WordSearch.letters is initialized in WordSearch.main(...) method and WordSearch.main() method is never called.

Note: There are a number of improvement opportunities in this code, but I have answered the question only.

Answer 3

The fast track to get it running would be to

1) Change in WordSearch from

public static void main(String[] args) {

to static initialization:

static  {
    //populating the arrayList with Strings, some which are in the wordsearch and some which aren't
    words.add("ghost");     words.add("knife");     words.add("patch");     words.add("ghoul");     words.add("apple");

Next in WordSearchSwing you need to change the code to

    Object[] title = {"First","2nd","r3d","4th","5th","6th"};
    table = new JTable(WordSearch.letters, title);
    JScrollPane scrollPane = new JScrollPane(table);
    contentPane.add(scrollPane, BorderLayout.CENTER);

to see the first 6 columns, add more as you like, and to also display the header.

You would then get something like this: