对象在不重写的情况下使用的是Object的equals方法和hashcode方法,从Object类的源码我们知道,默认的equals 判断的是两个对象的引用指向的是不是同一个对象;而hashcode也是根据对象地址生成一个整数数值; 另外我们可以看到Object的hashcode()方法的修饰符为native,表明该方法是否操作系统实现,java调用操作系统底层代码获取哈希...
For multiple objects x, y, and z, ifx.equals(y)returnstrueandy.equals(z)returnstrue, thenx.equals(z)should returntrue. Multiple invocations ofx.equals(y)should return same result, unless any of the object properties is modified that is being used in theequals()method implementation. Object c...
Add this method to theEmployeeclass, andEqualsTestwill start returning"true". So are we done? Not yet. Let’s test the above-modifiedEmployeeclass again in a different way. importjava.util.HashSet;importjava.util.Set;publicclassEqualsTest{publicstaticvoidmain(String[]args){Employeee1=newEmploye...
"Note that it is generally necessary to override thehashCodemethod whenever this method(equals) is overridden, so as to maintain the general contract for thehashCodemethod, which states that equal objects must have equal hash codes." 如果你重写了equals()方法,那么一定要记得重写hashCode()方法.我们...
Object.equals方法默认实现的是用==,即比较是否指向同一个对象: publicclassObject{//...publicbooleanequals(Objectobj){return(this==obj);}//...} 1.2 hashCode方法 JavaDoc对hashcode方法的介绍: Returns a hash code value for the object. This method is supported for the benefit of hash tables such...
hashCode() method 它将哈希码值作为整数返回。 Hashcode值主要用于基于散列的集合,如HashMap,HashSet,HashTable... .etc。必须在覆盖equals()方法的每个类中重写此方法。 语法: publicinthashCode()// This method returns the hash code value// for the object on which this method is invoked.//当这个方法...
* If two objects are equal according to the {@code equals(Object)} * method, then calling the {@code hashCode} method on each of * the two objects must produce the same integer result. * It is not required that if two objects are unequal * according to the {@...
Equal method and hashcode if we override equal method and hashcode,which method will run first and why? equalshashcode 2nd Nov 2017, 9:00 AM oyl 1 RespostaResponder + 1 Has nothing to do with "running". The only rule is that if equals returns true the hashcodes should be equal as we...
1. Java 里面有了 == 运算符,为什么还需要 equals ? ==比较的是对象地址,equals比较的是对象值 先来看一看Object类中equals方法: public boolean equals(Object obj) { return (this == obj); } 我们看到equals方法同样是通过==比较对象地址,并没有帮我们比较值。Java 世界中Object绝对是”老祖宗” 的存在...
"Note that it is generally necessary to override the hashCode method whenever this method(equals) is overridden, so as to maintain the general contract for the hashCode method, which states that equal objects must have equal hash codes." ...