java - 32 位整数上的 RotateLeft 操作

Question

我一直在为我的计算机组织类(class)开发不同的项目，并且我们一直在研究 BitWise 操作。我们当前的任务是为 java 编写一个自制的“rotateLeft”方法。

虽然 java 已经有了 Integer.rotateLeft，但我当前的任务是编写一个程序来使用该程序。

注意:int 变量等于这些位字符串

x1 = 3 = 00000000000000000000000000000011
x2 = -11= 1111111111111111111111111111110101

我当前的计划是:

public class Demo
 {
     public static void main(String[]args)
    {
         int x1=3, x2=-11;
         System.out.print("x1:            ");
         BitWise.printbit(x1);
         System.out.print("rotateLeft(x1,2):  ");
         BitWise.printbit(rotateLeft(x1,2));
         System.out.print("x2:            ");
         BitWise.printbit(x2);
         System.out.print("rotateLeft(x2,2):  ");
          BitWise.printbit(rotateLeft(x2,2));
        }
         public static int rotateLeft(int i, int distance)
         {
           int mask= i>>distance;
          return mask;

          }
       }

此操作适用于 x1 位模式，但是，它只是移位位，而不是实际旋转它们。

有什么建议吗？

Answer 1

这对我有用:

public static void main(String[] args) {
  int x1 = 3;
  int x2 = -11;

  int x1IntegerRotated = Integer.rotateLeft(x1, 2);
  int x1SelfRotated = rotateLeft(x1, 2);
  System.out.printf("x1 = %d(%s)%n",               x1,               printIntBitwise(x1));
  System.out.printf("x1IntegerRotated = %d(%s)%n", x1IntegerRotated, printIntBitwise(x1IntegerRotated));
  System.out.printf("x1SelfRotated = %d(%s)%n",    x1SelfRotated,    printIntBitwise(x1SelfRotated));

  System.out.println();

  int x2IntegerRotated = Integer.rotateLeft(x2, 2);
  int x2SelfRotated = rotateLeft(x2, 2);
  System.out.printf("x2 = %d(%s)%n",               x2,               printIntBitwise(x2));
  System.out.printf("x2IntegerRotated = %d(%s)%n", x2IntegerRotated, printIntBitwise(x2IntegerRotated));
  System.out.printf("x2SelfRotated = %d(%s)%n",    x2SelfRotated,    printIntBitwise(x2SelfRotated));
}

private static int rotateLeft(int value, int distance) {
  int mask = (1 << distance) - 1;
  int leftPart = (value << distance) & (~mask);
  int rightPart = (value >> (32 - distance)) & (mask);

  int result = leftPart | rightPart;

  return result;
}

private static String printIntBitwise(int a) {
  StringBuilder sb = new StringBuilder();

  for(int i = 1; i <= 32; i++) {
    sb.append(Math.abs((a & (1 << (32 - i))) >> (32 - i)));
  }

  return sb.toString();
}