Added a method to get the pieces in order.

src/Assignments/A1/models/Board.java

@@ -1,5 +1,7 @@
 package Assignments.A1.models;
 
+import java.util.Arrays;
+
 /**
  * This class keeps track of the current state (whether in permutation or not) of the board.
  *
@@ -8,7 +10,7 @@ package Assignments.A1.models;
  */
 public class Board {
 
-    private final Piece[] pieces;
+    private Piece[] pieces;
 
     /**
      * Default constructor that generates the solved board.
@@ -26,18 +28,24 @@ public class Board {
     /**
      * Constructor used to create a board with a pre-provided board.
      *
-     * @precondition board.length == 9
+     * @precondition board != null
      * @postcondition a board is created with given locations
      *
      * @param board the provided state of the board.
      */
-    public Board(Piece[] board) {
-        if (board.length != 9) {
-            throw new IllegalArgumentException("The board must be a array size of 9.");
+    public Board(Board board) {
+        if (board == null) {
+            throw new IllegalArgumentException("The board must be valid an initialized.");
+        }
+        this.pieces = new Piece[9];
+        for (int index = 0; index < 9; index++) {
+            if (board.getPiece(index) != null) {
+                this.pieces[index] = new Piece(board.getPiece(index));
+            }
         }
-        this.pieces = board;
     }
 
+
     /**
      * Checks the status of a place on the board. If the location is taken or not.
      *
@@ -88,6 +96,130 @@ public class Board {
         throw new IllegalStateException("The state of the board must have 1 empty space.");
     }
 
+    /**
+     * Takes two values on the board and swaps them if possible.
+     *
+     * @precondition board.get(first).validMove(second) == true
+     *            || board.get(second).validMove(first) == true
+     * @postcondition the values are swapped
+     *
+     * @param first the first index of the values being swapped
+     * @param second the second index of the values being swapped
+     * @return if the values were swapped or not.
+     */
+    public boolean swap(int first, int second) {
+        // Checks if the first piece is empty and the second is not.
+        if (this.pieces[first] == null && this.pieces[second] != null) {
+            // Checks if the moves are valid
+            if (this.pieces[second].validMove(first, this)) {
+                // Swaps the values
+                this.pieces[first] = this.pieces[second];
+                this.pieces[second] = null;
+                return true; // Successful Swap
+            }
+        } else if (this.pieces[second] == null && this.pieces[first] != null) { // Checks the inverse.
+            // Checks if the moves are valid
+            if (this.pieces[first].validMove(second, this)) {
+                // Swaps the values
+                this.pieces[second] = this.pieces[first];
+                this.pieces[first] = null;
+                return true; // Successful Swap
+            }
+        }
+        return false;
+    }
+
+    /**
+     * Gets the pieces in order in a single array of size 8.
+     *
+     * @precondition none
+     * @postcondition none
+     *
+     * @return the ordered list of values.
+     */
+    public Piece[] getPiecesInOrder() {
+        Piece[] ordered = new Piece[8];
+        boolean foundSpace = false;
+        for (Piece curr : this.pieces) {
+            if (curr == null) {
+                foundSpace = true;
+            } else if (!foundSpace) {
+                ordered[curr.getLoc()] = curr;
+            } else {
+                ordered[curr.getLoc()-1] = curr;
+            }
+        }
+        return ordered;
+    }
+
+    /**
+     * Hashes the board by adding the pieces to an array and hashes the array.
+     *
+     * @precondition none
+     * @postcondition none
+     *
+     * @return the hash of the board.
+     */
+    @Override
+    public int hashCode() {
+        int[] hashValues = new int[9];
+
+        for (int i = 0; i < 9; i++) {
+            if (this.pieces[i] != null) {
+                hashValues[i] = this.pieces[i].getValue();
+            } else {
+                hashValues[i] = 0;
+            }
+        }
+
+        return Arrays.hashCode(hashValues);
+    }
+
+    /**
+     * Checks if this and the other object are the same.
+     * @precondition none
+     * @postcondition they are compared.
+     *
+     * @param o the other object.
+     * @return if they are the same, True
+     *         if they are not,      False
+     */
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) {
+            return true;
+        }
+        if (o == null) {
+            return false;
+        }
+        if (this.getClass() != o.getClass()) {
+            return false;
+        }
+        Board other = (Board) o;
+        for (int i = 0; i < 9; i++) {
+            if (this.pieces[i].getValue() != other.pieces[i].getValue()
+                || this.pieces[i].getLoc() != other.pieces[i].getLoc()) {
+                return false;
+            }
+        }
+        return true;
+    }
+
+    /**
+     * Specifies a way of printing out the board with its current state.
+     * @return the current state formatted.
+     */
+    @Override
+    public String toString() {
+        String result = "";
+        for (int i = 0; i < 9; i++) {
+            result += i + " ";
+            if ((i+1) % 3 == 0) {
+                result += "\n";
+            }
+        }
+        return result;
+    }
 
     /* Private Methods Below. End of Java Docs. */
 
@@ -95,4 +227,4 @@ public class Board {
     private boolean invalidLocation(int loc) {
         return (loc < 0 || loc > 8);
     }
-}
+}

src/Assignments/A1/models/Piece.java

@@ -25,11 +25,26 @@ public class Piece {
         if (value < 1 || value > 8) {
             throw new IllegalArgumentException("The piece value is not valid. Valid Range: 1 <= Value <= 8");
         }
-
         this.setLoc(loc);
         this.value = value;
     }
 
+    /**
+     * Creates a new piece from an existing piece.
+     *
+     * @precondition piece != null
+     * @postcondition a copied piece is created.
+     *
+     * @param piece the piece being copied
+     */
+    public Piece(Piece piece) {
+        if (piece == null) {
+            throw new IllegalArgumentException("The piece cannot be null.");
+        }
+        this.loc = piece.getLoc();
+        this.value = piece.getValue();
+    }
+
     /**
      * Moves the piece to a new location.
      *

src/Assignments/A1/resources/Constants.java

@@ -0,0 +1,8 @@
+package Assignments.A1.resources;
+
+public class Constants {
+
+    /* Used to prevent DFS from going down only 1 branch */
+    public static final int MAX_DEPTH = 100;
+
+}