英文:
how to transfer elements from UnorderedList to array using iterable
问题
public class Slope<E> implements Comparable {
private Trail[] trail;
private int ranking;
private int count;
public Slope(ArrayUnorderedList<Trail> path) {
trail = new Trail[10];
Iterator<Trail> iter = path.iterator();
for (int i = 0; i < trail.length; i++) {
while (iter.hasNext()) {
trail[i] = iter.next();
count++;
}
}
}
}
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:
public class Slope<E> implements Comparable {
private Trail[] trail;
private int ranking;
private int count;
public Slope (ArrayUnorderedList<Trail> path) {
trail = new Trail[10];
Iterator<Trail> iter = path.iterator();
for (int i = 0; i < trail.length; i++) {
while (iter.hasNext()) {
trail[i] = iter.next();
count ++;
}
}
}
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：
public class Slope<E> implements Comparable {
private Trail[] trail;
private int ranking;
private int count;
public Slope(ArrayUnorderedList<Trail> path) {
trail = new Trail[10];
Iterator<Trail> iter = path.iterator();
int i = 0;
while (iter.hasNext() && i < trail.length) {
trail[i++] = iter.next();
count++;
}
}
}
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:
public class Slope<E> implements Comparable {
private Trail[] trail;
private int ranking;
private int count;
public Slope (ArrayUnorderedList<Trail> path) {
trail = new Trail[10];
Iterator<Trail> iter = path.iterator();
int i = 0;
while (iter.hasNext() && i < trail.length) {
trail[i++] = iter.next();
count++;
}
}
}
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