Question

我正在使用这个课程作为另一个课程的一部分，我想知道为什么第二个System.out.print没有打印任何东西。我对其他算法做了同样的事情并且工作得很好。它仍然在方法内，所以我不确定为什么它不会打印

public class EnhancedBubbleSort
{
   int temp = 0;
   boolean sorted = false;
   long counter1 = 0, counter2 = 0;

   public void sort(int[] numbers)
   {  
      System.out.print("Before Enhanced Bubble Sort: ");
      for(int a: numbers)
         System.out.print(a + ", ");

      int lastSwap = numbers.length-1;
      for(int i=1; i<numbers.length; i++) 
      {
         boolean is_sorted = true;
         int currentSwap = -1;

         for(int j=0; j < lastSwap; j++) 
         {
            counter1++;
            if(numbers[j] > numbers[j+1]) 
            {
               counter2++;
               temp = numbers[j];
               numbers[j] = numbers[j+1];
               numbers[j+1] = temp;
               is_sorted = false;
               currentSwap = j;
            }
         }  
         if(is_sorted) 
            return;
         lastSwap = currentSwap;
      }

      System.out.print("\nAfter Enhanced Bubble Sort: ");
      for(int a: numbers)
         System.out.print(a + ", "); 
   }
}

Answer 1

请修改下面的代码，它可以正常工作：

class EnhancedBubbleSort
{
   int temp = 0;
   boolean sorted = false;
   long counter1 = 0, counter2 = 0;

   public void sort(int[] numbers)
   {  
      System.out.print("Before Enhanced Bubble Sort: ");
      for(int a: numbers)
      System.out.print(a + ", ");

      int lastSwap = numbers.length-1;
      for(int i=1; i<numbers.length; i++) 
      {
         boolean is_sorted = true;
         int currentSwap = -1;

         for(int j=0; j < lastSwap; j++) 
         {
            counter1++;
            if(numbers[j] > numbers[j+1]) 
            {
               counter2++;
               temp = numbers[j];
               numbers[j] = numbers[j+1];
               numbers[j+1] = temp;
               is_sorted = false;
               currentSwap = j;
            }
         }  
         if(is_sorted) 
          break;   // Use break statement instead of return one
      lastSwap = currentSwap;
      }
      System.out.print("\nAfter Enhanced Bubble Sort: ");
      for(int a: numbers)
         System.out.print(a + ", "); 
   }
}

输出：

jshell> new EnhancedBubbleSort().sort(data)
Before Enhanced Bubble Sort: 1, 2, 3, 4, 
After Enhanced Bubble Sort: 1, 2, 3, 4,

Answer 2

当您执行/** * Parses the given string as an Instant, and returns null if not parseable */ public Instant parse(String s) { try { return Instant.parse(s); } catch (DateTimeParseException e) { return null; } }时，您将离开if(is_sorted) return;，并且不会执行任何进一步的陈述。您想要做的是void sort()，离开if(is_sorted) break;循环。

我的第二个System.out.print没有打印，但编译正常

2 个答案: