如何使用可迭代对象将UnorderedList中的元素转移到数组中

huangapple
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英文:

how to transfer elements from UnorderedList to array using iterable

问题

  1. public class Slope<E> implements Comparable {
  3.     private Trail[] trail;
  4.     private int ranking;
  5.     private int count;
  7.     public Slope(ArrayUnorderedList<Trail> path) {
  8.         trail = new Trail[10];
  10.         Iterator<Trail> iter = path.iterator();
  11.         for (int i = 0; i < trail.length; i++) {
  12.             while (iter.hasNext()) {
  13.                 trail[i] = iter.next();
  14.                 count++;
  15.             }
  16.         }
  17.     }
  18. }

我想使用迭代器逐个将UnorderedList的每个元素传输到trail数组中，但它只会更新数组中的第一个值，其余值仍然指向null。

英文: 
  1. public class Slope&lt;E&gt; implements Comparable {
  2. 	
  3. 	private Trail[] trail;
  4. 	private int ranking;
  5. 	private int count;
  6. 	
  7. 	public Slope (ArrayUnorderedList&lt;Trail&gt; path) {
  8. 		trail = new Trail[10];
  9. 		
  10. 		Iterator&lt;Trail&gt; iter = path.iterator();
  11. 		for (int i = 0; i &lt; trail.length; i++) {
  12. 			while (iter.hasNext()) {
  13. 				trail[i] = iter.next();
  14. 				count ++;
  15. 			}
  16. 			
  17. 		}
  18. 		
  19. 	}

I want to transfer each of the UnorderedList elements to the
trail array one-by-one using the iterator but it only updates the first value in the array and the rest still point to null.

答案1

得分: 0

问题出在你的循环结构上；你对每个i的值都迭代了一遍iter。这会导致你只会设置trail[0]的值，因为一旦你对i=0迭代完成，它就结束了；对于所有其他i的值，iter.hasNext()都将是false。

要解决这个问题，你需要在没有封闭的for循环的情况下迭代iter，同时仍然需要跟踪一个运行中的索引，可能会像这样：

  1. public class Slope<E> implements Comparable {
  2.     
  3.     private Trail[] trail;
  4.     private int ranking;
  5.     private int count;
  6.     
  7.     public Slope(ArrayUnorderedList<Trail> path) {
  8.         trail = new Trail[10];
  9.  
  10.         Iterator<Trail> iter = path.iterator();
  11.         int i = 0;
  12.         while (iter.hasNext() && i < trail.length) {
  13.             trail[i++] = iter.next();
  14.             count++;
  15.         }
  16.     }
  17. }
英文:

The issue is with your loop structure; you iterate over iter for every single value of i. This will cause you only ever to set the value of trail[0] because once you have iterated over iter for i=0, it's done; iter.hasNext() will be false for all other values of i.

To fix this, you will need to iterate over iter without an enclosing for-loop while still keeping track of a running index, which might look something like this:

  1. public class Slope&lt;E&gt; implements Comparable {
  2.     
  3.     private Trail[] trail;
  4.     private int ranking;
  5.     private int count;
  6.     
  7.     public Slope (ArrayUnorderedList&lt;Trail&gt; path) {
  8.         trail = new Trail[10];
  9.  
  10.         Iterator&lt;Trail&gt; iter = path.iterator();
  11.         int i = 0;
  12.         while (iter.hasNext() &amp;&amp; i &lt; trail.length) {
  13.             trail[i++] = iter.next();
  14.             count++;
  15.         }
  16.     }
  17. }

huangapple
  • 本文由 发表于 2020年7月28日 22:16:30
  • 转载请务必保留本文链接：https://go.coder-hub.com/63136218.html
  • java
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