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java——如何比较两组对象不使用 Comparator 和 Streams 覆盖 equals/hashCode

发布时间:2022-09-09 09:47:46 248
# 移动端

我有两个Set它是这样的:

Set s1 = createBooks();
Set s2 = createBooks(); // or any set of values

这种方法:

private Set createBooks() {

    List name = Arrays.asList("book 1", "book 2", "book 3");
    List type = Arrays.asList(BookType.TYPEONE, BookType.TYPETWO);

    Set listOfBooks = new HashSet<>();

    for(int i=0; i<2; i++) {
        Book book = new Book();
        book.setName(name.get(i));
        book.setType(type.get(i));
        listOfBooks.add(books);
    }

    return listOfBooks;
}

还有这门课:

Class Book {

 private String name;
 private BookType type;

 //here is getter and setter ...

 }

我确实做到了Comparator,但我不确定它是否正常工作:

   Comparator comparingBooks = (o1, o2) -> {
        if (o1.getName().compareTo(o2.getName()) == 0) {
            return o1.getType().compareTo(o2.getType());
        }
        return o1.getName().compareTo(o2.getName());
    };


     //I did try this implementation but am not sure it's working as well:

     //Comparator comparingBooks = Comparator.comparing((Book b)->b.getNName())
              .thenComparing(b->b.getType());

当预期结果为true:

s1 = (new Book("book 1", BookType.ONE), new Book("book 2", BookType.TWO));
s2 = (new Book("book 1", BookType.ONE), new Book("book 2", BookType.TWO));

当预期结果为false:

s1 = (new Book("book 1", BookType.ONE), new Book("book 2", BookType.TWO));     
s2 = (new Book("book 1", BookType.ONE), new Book("book 2", BookType.ONE));

我需要将这些集合与以下内容进行比较:

// this flag should validate any difference of Name 
// and Type by returning true, 
// if both Sets have exactly the same objects, 
// it should return false.
boolean compareBooks = s1.stream().anyMatch(a -> s2.stream().anyMatch(b -> comparingBooks.compare(a, b) != 0));

我也尝试过,但没有成功,总是返回相同的值:

    boolean compareBooks = SetUtils.isEqualSet(s1, s2);

我没有equals和hashcode实现,无法实现。

java 8和comparator还有其他方法来检查和比较这些集合吗?

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