Java类对象不相等，即使它们相等[重复]

Question

嘿，我有两个 java 类对象，它们的键和值是相同的，但是当我检查 ob1.equals(obj2) 时它返回 false。

这里是代码：

   Category expected = new Category("01","lorem","custom");


  ResponseEntity<List<LinkedHashMap>> response = restTemplate.exchange("/api/categories", HttpMethod.GET,
                        null, new ParameterizedTypeReference<List<LinkedHashMap>>() {});

LinkedHashMap result = response.getBody().get(0); // which is same as expected object

//check if equals

 private boolean areEqual(LinkedHashMap result, Category expected) {
        String catId = (String) obj.get("category_id"); //is 01
        String name = (String) obj.get("category_name"); // is lorem
        String sec = (String) obj.get("section_name");   // is custom
        DefaultCategory temp = new Category(catId, name, sec);
        return temp.equals(expected);  //<--------- returning false, even they are equal
    }

api返回这个类别

 @GetMapping("categories")
    public ResponseEntity<List<Category>> getDefaultCategories() {
        List<Category> categories = new ArrayList();
        categories.add(new Category("01","lorem","custom"));
        return new ResponseEntity<>(categories, HttpStatus.OK);
    }

Answer 1

标准.equals(...) 检查两个对象是否相同。如果您想将两个对象与其字段进行比较。您可以覆盖equals 方法，如下所示。

public class DefaultCategory {
    private String catId;
    private String name;
    private String sec;

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (!(o instanceof DefaultCategory)) return false;

        DefaultCategory other = (DefaultCategory) o;
        if(!Objects.equals(other.catId, catId)) return false;
        if(!Objects.equals(other.name, name)) return false;
        if(!Objects.equals(other.sec, sec)) return false;

        return true;
    }
}

Answer 2

因为 expected 是子类而 temp 是超类，反之亦然。您正在比较两个不同的对象（类型）。将您临时转换为类别，您会没事的。或者覆盖你的 equals 以允许混合类型比较。