Board.java

import java.util.*;
public class Board
{
    Tile[][]table;
    int emptyX;
    int emptyY;
    String total;
    boolean solved;
    public Board()
    {
        table = new Tile[3][3];
        total = "";
        solved = false;
    }

    public void setBoard(){//initializes board
        //randomizes digits
        int[] a = new int[9];
        int rand;
        ArrayList<Integer> numbers = new ArrayList<>(Arrays.asList(1, 2, 3, 4, 5, 6,7,8,9));
        for(int i = 0; i < numbers.size(); i++){
            rand = (int)(Math.random() * 9);
            if(a[rand] == 0){
                a[rand] = numbers.get(i);
            }else{
                i--;
            }
        }

        //places in board using array 1-9
        int spot = 0;
        for(int i = 0; i < 3; i++){
            for(int j = 0; j < 3; j++){
                table[i][j] = new Tile(a[spot]-1);
                if(a[spot]-1 == 0){
                    emptyX = j;
                    emptyY = i;
                }
                a[spot]-=1;
                spot++;

            }
        }
        if(!solvableBoard(a)){
            System.out.println("Unsolvable. Trying again.");
            setBoard();
        }
        total = "";
        for(int i = 0; i < a.length; i++){
            total += a[i];
        }
    }

    public boolean solvableBoard(int[]board){//determines if the board is solvable
        int totalInverted = 0;
        for (int i = 0; i < board.length; i++) {
            if (board[i] == 0)
                continue;
            int testInverted = 0;
            for(int j = i+ 1; j < board.length; j++){
                if(board[i] > board[j] && board[j] != 0){
                    testInverted++;
                }
            }
            //System.out.format("%d: %d inversions\n", board[i], testInverted);
            totalInverted += testInverted;
        }
        if(totalInverted % 2 == 0){
            return true;
        }
        return false;
    }

    public void move(int x, int y){//moves tile if applicable
        if(solved){
            return;
        }
        
        if((Math.abs(x-emptyX) == 1 && y == emptyY) || (Math.abs(y-emptyY) == 1 && x == emptyX)){
            System.out.println("Move " + table[y][x].digit);
            Tile hold = table[y][x];
            table[y][x] = table[emptyY][emptyX];
            table[emptyY][emptyX] = hold;
            emptyX = x;
            emptyY = y;
        }else{
            System.out.println("No move");
        }
        if(isSolved()){
            solved = true;
        }
    }

    public boolean isSolved(){ //0 first
        int spot = 0;
        for(int i = 0; i < 3; i++){
            for(int j = 0; j < 3; j++){
                if(spot != table[i][j].digit){
                    return false;
                }
                spot++;
            }
        }
        return true;
    }

}

GUI.java

import java.awt.Color;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.WindowConstants;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Point;
import java.awt.event.MouseListener;
import java.awt.event.MouseEvent;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
import java.util.*;
import java.io.*;
import java.awt.Font;

public class GUI {
    private JFrame frame;
    public static Board table;
    public GUI() {
        table = new Board();
        table.setBoard();
        frame = new JFrame("Tiles Program");
        frame.setSize(800, 800);
        frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        frame.setPreferredSize(frame.getSize());
        frame.add(new InnerProgram(frame.getSize()));
        frame.pack();
        frame.setVisible(true);

    }

    public static void main(String... argv) {
        new GUI();
    }

    public static class InnerProgram extends JPanel implements Runnable, MouseListener  {

        ArrayList<String> names = new ArrayList<String>();
        private Thread animator;
        Dimension d;
        String str = "";

        public InnerProgram (Dimension dimension) {
            setSize(dimension);
            setPreferredSize(dimension);
            addMouseListener(this);
            addKeyListener(new TAdapter());
            setFocusable(true);
            d = getSize();

            //for animating the screen - you won't need to edit
            if (animator == null) {
                animator = new Thread(this);
                animator.start();
            }
            setDoubleBuffered(true);
        }

        @Override
        public void paintComponent(Graphics g) {
            Graphics2D g2 = (Graphics2D)g;

            g2.setColor(Color.black);
            g2.fillRect(0, 0,(int)d.getWidth() , (int)d.getHeight());

            Color co = new Color(255,255,255);
            g2.setColor(co);
            int fontSize = 100;
            g2.setFont(new Font("TimesRoman", Font.PLAIN, fontSize));
            //g2.drawString(table.total + "",20,70);

            for(int i = 0; i < 3; i++){
                for(int j = 0; j < 3; j++){
                    g2.drawRect(j*200 + 100,i*200+100,200,200);
                    //System.err.println(i +" " + j);
                    if(table.table[j][i].digit != 0)
                        g2.drawString("" + table.table[j][i].digit , (i+1) *200,(j+1) *200);
                }
            }

        }

        public int random (int a, int b){    
            int max=a;
            int min=b;
            int random=(int)(Math.random() * (max - min) + min);

            return random;
        }

        public void mousePressed(MouseEvent e) {
            int x = e.getX();
            int y = e.getY();
            str = x + " " + y;

            if(x < 100 || y < 100 || x > 700 || y > 700){
                table.setBoard();
            }else{
                System.out.println("Into Move: " + (x-100)/200 + " " + (y-100)/200);
                table.move((x-100)/200, (y-100)/200);
            }

        }

        public void mouseReleased(MouseEvent e) {
        }

        public void mouseEntered(MouseEvent e) {
        }

        public void mouseExited(MouseEvent e) {
        }

        public void mouseClicked(MouseEvent e) {
        }

        private class TAdapter extends KeyAdapter {

            public void keyReleased(KeyEvent e) {
                int keyr = e.getKeyCode();

            }

            public void keyPressed(KeyEvent e) {
                int key = e.getKeyCode();
                // String c = KeyEvent.getKeyText(e.getKeyCode());
                //  c = Character.toString((char) key);

            }
        }//end of adapter

        public void run() {
            long beforeTime, timeDiff, sleep;
            beforeTime = System.currentTimeMillis();
            int animationDelay = 37;
            long time = System.currentTimeMillis();
            while (true) {// infinite loop
                // spriteManager.update();
                repaint();
                try {
                    time += animationDelay;
                    Thread.sleep(Math.max(0, time - System.currentTimeMillis()));
                } catch (InterruptedException e) {
                    System.out.println(e);
                } // end catch
            } // end while loop
        }// end of run

    }//end of class
}

Tile.java

public class Tile
{
    int digit;
    public Tile(int d)
    {
        digit = d;
    }

}