Java循环没有做它应该做的事

Question

递归conflictCheck（）方法有问题。现在看来很好。我有测试打印线，看起来不错。现在，当某些事情发生冲突（返回true）时，我的playChess（）方法应该通过调整节点的第二个变量来解决冲突，依此类推。

我的结果是字面上：

1,1

2,3

3,1

4,3

5,1 ...

即使输出说“哦，我们有冲突”，它不会采取行动它一旦达到X，3

public static boolean conflictCheck(QueenNode a, QueenNode b) { 
    //checks for conflicts between head and all other nodes in the stack 
    if (b == null) { 
     System.out.println("Attempting Conflict Check: Nothing to Compare to"); 
     return false; 
    } 

    if (a.getRow()!=b.getRow() && a.getColumn()!=b.getColumn() && !diagonal(a,b)){ 
     System.out.println("Comparing " + a.getRow() + " ," + a.getColumn() + 
            " And " + b.getRow() + " , " + b.getColumn()); 
     conflictCheck(a,b.getNext()); 
    } 
    else { 
     System.out.println("There is a conflict with " +a.getRow() + "," + a.getColumn() 
          + " And " + b.getRow() + "," + b.getColumn()); 
     return true; 
     } 
    return false; 
} 


    public static void playChess() { 
    System.out.println("Playing chess"); 
    //Either there is a conflict between head and another node, the stack isn't full, or we have solution 
    if (conflictCheck(head, head.getNext())) { 
     if (head.getColumn() == 8) { 
      queens.pop(); 
     } 
     else if (!queens.isEmpty()) { 
      System.out.println("Adjusting head"); 
      head.setColumn(head.getColumn()+1); 
      System.out.println("Head is now " + head.getRow() + ", " + head.getColumn()); 
      playChess(); 

     } 
    } 

    else if (queens.size() < 8) { 
     System.out.println("Stack isn't full yet"); 
     queens.push(queens.size()+1,1); 
     queens.viewPieces(); 
     playChess(); 
     } 
    else { 
     success= true; 
     System.out.println("Success"); 
     queens.viewPieces(); 
     return; 
    } 
} 

整个输出：

The stack 
1, 1 
End of stack 
Playing chess 
Attempting Conflict Check: Nothing to Compare to 
Stack isn't full yet 
The stack 
2, 1 
1, 1 
End of stack 
Playing chess 
There is a conflict with 2,1 And 1,1 
Adjusting head 
Head is now 2, 2 
Playing chess 
problem 
There is a conflict with 2,2 And 1,1 
Adjusting head 
Head is now 2, 3 
Playing chess 
Comparing 2 ,3 And 1 , 1 
Attempting Conflict Check: Nothing to Compare to 
Stack isn't full yet 
The stack 
3, 1 
2, 3 
1, 1 
End of stack 
Playing chess 
Comparing 3 ,1 And 2 , 3 
There is a conflict with 3,1 And 1,1 
Stack isn't full yet 
The stack 
4, 1 
3, 1 
2, 3 
1, 1 
End of stack 
Playing chess 
There is a conflict with 4,1 And 3,1 
Adjusting head 
Head is now 4, 2 
Playing chess 
problem 
There is a conflict with 4,2 And 3,1 
Adjusting head 
Head is now 4, 3 
Playing chess 
Comparing 4 ,3 And 3 , 1 
There is a conflict with 4,3 And 2,3 
Stack isn't full yet 
The stack 
5, 1 
4, 3 
3, 1 
2, 3 
1, 1 
End of stack 
Playing chess 
Comparing 5 ,1 And 4 , 3 
There is a conflict with 5,1 And 3,1 
Stack isn't full yet 
The stack 
6, 1 
5, 1 
4, 3 
3, 1 
2, 3 
1, 1 
End of stack 
Playing chess 
There is a conflict with 6,1 And 5,1 
Adjusting head 
Head is now 6, 2 
Playing chess 
problem 
There is a conflict with 6,2 And 5,1 
Adjusting head 
Head is now 6, 3 
Playing chess 
Comparing 6 ,3 And 5 , 1 
There is a conflict with 6,3 And 4,3 
Stack isn't full yet 
The stack 
7, 1 
6, 3 
5, 1 
4, 3 
3, 1 
2, 3 
1, 1 
End of stack 
Playing chess 
Comparing 7 ,1 And 6 , 3 
There is a conflict with 7,1 And 5,1 
Stack isn't full yet 
The stack 
8, 1 
7, 1 
6, 3 
5, 1 
4, 3 
3, 1 
2, 3 
1, 1 
End of stack 
Playing chess 
There is a conflict with 8,1 And 7,1 
Adjusting head 
Head is now 8, 2 
Playing chess 
problem 
There is a conflict with 8,2 And 7,1 
Adjusting head 
Head is now 8, 3 
Playing chess 
Comparing 8 ,3 And 7 , 1 
There is a conflict with 8,3 And 6,3 
Success 
The stack 
8, 3 
7, 1 
6, 3 
5, 1 
4, 3 
3, 1 
2, 3 
1, 1 
End of stack 

Answer 1

由于这是功课，有一个小提示：

您不要在冲突采取行动的理由您发现的原因很可能是因为您忽略了从boolean conflictCheck(QueenNode a, QueenNode b)递归调用的返回值conflictCheck(a,b.getNext());。

第012页的this excellent work by E.W.Dijkstra深入探讨了八个女王的问题。它使用ALGOL-60编码（甚至在我的时间之前就已经过时），但这些想法与语言无关。