I am working on randomizing which move my knight takes in my knight's tour code. For some reason though, my switch statement always goes to default, instead of executing a possible move. I know my possible moves methods work because I have separately ran firstMoveChoice()
on it's own and it worked. So I know the problem is with my random move picker, but I can't seem to figure it out.
Thanks for your help and time in advance! It is really much appreciated as I have looked this problem over and cannot find the answer.
public class MoveKnight extends Moves {
public int[][] moveTheKnight() {
Moves switchBetweenMoves = new Moves();
switchBetweenMoves.startingLocation();
while (knight != 64) {
int randomMove = new Random().nextInt();
switch (randomMove) {
case 1:
switchBetweenMoves.firstMoveChoice();
break;
case 2:
switchBetweenMoves.secondMoveChoice();
break;
case 3:
switchBetweenMoves.thirdMoveChoice();
break;
// other possible moves
default:
System.out.println("No more possible moves.");
break;
}
break;
}
return board;
}
}
Here is the result of the above code:
1 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0
No more possible moves.
BUILD SUCCESSFUL (total time: 0 seconds)
Here is my Main method:
public static void main(String[] args) {
MoveKnight myKnight = new MoveKnight();
myKnight.moveTheKnight();
}
Here is my ChessBoard class:
public class ChessBoard {
int[][] board;
public ChessBoard() {
this.board = new int[8][8];
}
}
Here is firstMoveChoice()
public int[][] firstMoveChoice() {
System.out.println();
x += 1;
y += 2;
if (x >= board.length) { // this tests to make sure the knight does not move off the row
System.out.println("Cannot move off board on x axis\n");
x -= 1;
y -= 2;
return board;
}
else if (y >= board.length) { // this tests to make sure the knight does not move off the column
System.out.println("Cannot move off board on y axis\n");
x -= 1;
y -= 2;
return board;
}
else if (board[x][y] != 0) { // this prevents the knight from landing on a previously landed on square
x -= 1;
y -= 2;
System.out.println("Cannot move onto a used square\n");
return board;
}
else { // this moves the knight when the above statements are false
board[x][y] = ++knight;
System.out.println("This executed and the knight moved\n");
for(int[] row : board) {
printRow(row);
}
if (knight == 64) {
System.out.println("Knight has completed the tour");
}
return board;
}
}
Here is thirdMoveChoice()
: It is practically the same as all the others, except for the change in numbers for the different moves.
public int[][] thirdMoveChoice() {
System.out.println();
x += 2;
y -= 1;
if (x >= board.length) { // this tests to make sure the knight does not move off the row
System.out.println("Cannot move off board on x axis\n");
x -= 2;
y += 1;
return board;
}
else if (y >= board.length) { // this tests to make sure the knight does not move off the column
System.out.println("Cannot move off board on y axis\n");
x -= 2;
y += 1;
return board;
}
else if (board[x][y] != 0) { // this prevents the knight from landing on a previously landed on square
x -= 2;
y += 1;
System.out.println("Cannot move onto a used square\n");
return board;
}
else { // this moves the knight when the above statements are false
board[x][y] = ++knight;
System.out.println("This executed and the knight moved\n");
}
for(int[] row : board) {
printRow(row);
}
if (knight == 64) {
System.out.println("Knight has completed the tour");
return board;
}
return board;
}
It's because random.nextInt()
return a value between -2,147,483,648 and 2,147,483,647
you should use the random.nextInt(int n)
that return a value between 0 inclusive and n exclusive
so replace
int randomMove = new Random().nextInt(); b
by
int randomMove = 1 + new Random().nextInt(3);
Also, you should assign new Random()
to a field that would be reused.