equals consistency: objects that are equal to each other must return the same hashCode collisions: unequal objects may have the same hashCode 3.2. Violating the Consistency ofhashCode()andequals() The second cr
public int hashCode(){ return this.color.length(); } 原文:Java equals() and hashCode() Contract 翻译:ImportNew.com-唐小娟
Object的规范中并没有明确要求equals()和hashCode()必须一致-- 它们的结果在随后的调用中将是相同的,假设“不改变对象相等性比较中使用的任何信息。”这听起来象“计算的结果将不改变,除非实际情况如此。”这一模糊声明通常解释为相等性和散列值计算应是对象的可确定性功能,而不是其它。 对象相等性意味着什么? 人们...
x.equals(y) return true y.equals(z) return true x.equals(z) return true 4.consistent-一致性 x.equals(y) return true //那么不管调用多少次,肯定都是返回true 5.与null的比较 x.equals(null) return false //对于none-null的x对象,每次必然返回false 6.于hashcode的关系 * Note that it is gener...
public boolean equals(Object obj) { if (!(obj instanceof Dog)) return false; if (obj == this) return true; return this.color.equals(((Dog) obj).color); } } 答案是不。 现在问题是由Java中的hashCode和equals contract引起的。hashCode()方法是Object类中的另一个方法。 约定是,如果两个对象...
简介:Java中Set的contains()方法 —— hashCode与equals方法的约定及重写原则翻译人员: 铁锚翻译时间: 2013年11月5日原文链接: Java hashCode() and equals() Contract for the contains(Object o) Met... Java中Set的contains()方法 —— hashCode与equals方法的约定及重写原则 ...
Java Object hashCode() is a native method and returns the integer hash code value of the object. The general contract of hashCode() method is: Multiple invocations of hashCode() should return the same integer value, unless the object property is modified that is being used in the equals() ...
As compared to the general contract specified by the equals method, the contract specified by the hashCode method is relatively simple and easy to understand. It simply states two important requirements that must be met while implementing the hashCode method. The third point of the contract, in ...
1.1. Contract betweenhashCode()andequals() Overriding the thehashCode()is generally necessary wheneverequals()is overridden to maintain the general contract for thehashCode()method, which states thatequal objects must have equal hash codes.
Objects that are equal (according to theirequals()) must return the same hash code.Different objects do not need to return different hash codes. The general contract ofhashCode()states: Whenever it is invoked on the same object more than once during an execution of a Java application,hashCode...