在IJVM中編寫遞歸函數

Question

我目前正在編寫一個遞歸解決河內塔的ijvm程序。我不知道如何設置方法中調用的方法的對象引用的編號。

這是java代碼，我使用「翻譯」的ijvm代碼：

public class Tower{ 
    public static void towers(int n, int i, int j) { 
    int k; 
    if (n == 1) { 
     System.out.println("Move a disk from " + i + " to " + j); 
    } else { 
     k = 6 - i - j; 
     towers(n - 1, i, k); 
     towers(1, i, j); 
     towers(n - 1, k, j); 
    } 
} 

    public static void main(String[] args){ 
    towers(5,1,3); 
    } 
} 

這是ijvm代碼：

;BIPUSH 0 is for the object reference 
BIPUSH 0 
BIPUSH 5 
BIPUSH 1 
BIPUSH 3 
INVOKEVIRTUAL tower 
HALT 

;the recursive method 
tower 4 1 
ILOAD 1 
BIPUSH 1 
IF_ICMPEQ L1 
BIPUSH 6 
ILOAD 2 
ISUB  
ILOAD 3 
ISUB 
ISTORE 4 

;this is for the method towers(n - 1, i, k); 
;BIPUSH 1 is for the object reference 
BIPUSH 1 
ILOAD 1 
BIPUSH 1 
ISUB 
ILOAD 2 
ILOAD 4 
INVOKEVIRTUAL tower 

;this is for the method towers(1, i, j); 
;BIPUSH 2 is for the object reference 
BIPUSH 2 
BIPUSH 1 
ILOAD 2 
ILOAD 3 
INVOKEVIRTUAL tower 

;this is for the method towers(n-1, k, j); 
;BIPUSH 3 is for the object reference 
BIPUSH 3 
ILOAD 1 
BIPUSH 1 
ISUB 
ILOAD 4 
ILOAD 3 
INVOKEVIRTUAL tower 

L1: ILOAD 3 
ILOAD 2 
SPRINT "Move a disk from " 
IPRINT 
SPRINT " to " 
IPRINT 
SPRINT "\n" 

Answer 1

的對象引用僅僅是一個佔位符，因爲IJVM不實現面向對象。你可以在那裏放置任何值。它將在INVOKEVIRTUAL例程中被覆蓋，但從未讀取。