为什么可以在IntelliJ上运行，这里运行不了

import java.util.HashSet; import java.util.Set; import java.util.Iterator; /* 包含猫的集 */ public class Solution { public static void main(String[] args) { Set<Cat> cats = createCats(); //在此编写你的代码. 第 3 步 Iterator<Cat> iterator = cats.iterator(); while(iterator.hasNext()){ Cat cat = iterator.next(); iterator.remove(); break; } printCats(cats); } public static Set<Cat> createCats() { //在此编写你的代码. 第 2 步 HashSet<Cat> catSet = new HashSet<Cat>(); catSet.add(new Cat()); catSet.add(new Cat()); catSet.add(new Cat()); return catSet; } public static void printCats(Set<Cat> cats) { // 第 4 步 for(Cat cat : cats){ System.out.println(cat); } } // 第 1 步 public static class Cat{ String name; Cat cat; public Cat(){ } public Cat(String name){ this.name = name; } } }

编译通过 public static void main(String[] args) { Set<Cat> cats = createCats(); Iterator<Cat> iterate = cats.iterator(); int i = 0; while (iterate.hasNext()){ Cat pair = iterate.next(); if(i == 0){ iterate.remove(); } i++; } printCats(cats); } public static Set<Cat> createCats() { Set<Cat> cats = new HashSet<Cat>(); cats.add(new Cat()); cats.add(new Cat()); cats.add(new Cat()); return cats; } public static void printCats(Set<Cat> cats) { for(Cat cat: cats){ System.out.println(cat); } } public static class Cat { public Cat(){ } }

Set中删除元素需要用到Iterator类的方法

Iterator<Cat> iterator = cats.iterator();
while (iterator.hasNext()) {
    Cat cat = iterator.next();
    iterator.remove();
    break;
}

I think the online judge system was not implemented well for this problem. To fulfil the requirements, I would suggest to modify two places. 1. Instead of using equals to find the object to remove, you may try to directly remove the first object when iterating the Cat set. 2. Instead of printing out the name of a cat, you may try to print out the object itself.