java assertEquals集

Question

我有两套:

 Set<Attribute> set1 = new HashSet<Attribute>(5);
 Set<Attribute> set2 = new HashSet<Attribute>(5);

 //add 5 attribute objects to each of them. (not necessarily the same objects)


 assertEquals(set1,set2); //<--- returns false, even though 
                         //the added attribute objects are equal

根据我的要求,覆盖了属性的equals方法:

public abstract class Attribute implements Serializable{

public int attribute;

public abstract boolean isNumerical();

@Override
public boolean equals(Object other){
    if(!(other instanceof Attribute)){
        return false;
    }

    Attribute otherAttribute = (Attribute)other;
    return (this.attribute == otherAttribute.attribute && 
            this.isNumerical() == otherAttribute.isNumerical());
}

}

在调试时,甚至没有调用equals方法!

有任何想法吗？

Answer 1

您没有覆盖hashCode(),这意味着将使用默认实现.在调用之前首先HashSet检查匹配的哈希码- 这就是它如何有效地找到潜在匹配的方法.(很容易"整理"一个整数.)equals

基本上,您需要以hashCode与您的equals方法一致的方式覆盖.