equals

问题 I would like to use the @EqualsAndHashCode annotation on my domain classes, but it seems the equals and hashCode methods generated by that annotation don't take hasMany fields into account. I don't see any way to change this with the annotation, but I'm hoping that I'm missing something because it is very convenient (if it works). 回答1: Define the hasMany relationship as a Set in the parent domain class, which we normally do not do as it is redundant. You also have to make sure you are using

问题 Is it possible to configure custom factories to generate values for the EqualsMethodTester and HashCodeMethodTester classes from org.meanbean.test ? When I pass the Configuration which works for BeanTester to EqualsMethodTester , I get the following messages in the error traceback: org.meanbean.factories.ObjectCreationException: Failed to create a value for property [demoUrl]. Failed to find suitable Factory for property=[demoUrl] of type=[class java.net.URL]. Please register a custom Factory

问题 Prompt for and input two integers “a” and “b” using syscalls Display one of the following statements depending on if a>b, or a=b or a You entered a greater than b You entered an equal to b You entered a less than b I have to get this prompt and I tried so hard to get it done. This is where I'm stucked, I'd really appreciate your help. .data p1: .asciiz "Please enter the first number ? " p2: .asciiz " Please enter the second number? " ans1: .asciiz " \nYou entered a greater than b " ans2:

问题 If two objects are equal then hashcode must be same. Then why does the any check in HashMap do - if (e.hash == hash && ((k = e.key) == key || (key != null && key.equals(k)))) { Instead of simply if ((k = e.key) == key || (key != null && key.equals(k)))) { 回答1: If two objects are equal then hashcode must be same. In this case, take it the other way: "If hashcodes of two objects are different, they can't be equal" So, here we are simply short-circuiting the comparison using equals() by first

问题 Lets say I Have class: public class Ident { public String Name { get; set; } public String SName { get; set; } } and also one more: class IdenNode { public Ident id { get; set; } public List<IdenNode> Nodes { get; set; } public IdenNode() { Nodes = new List<IdenNode>(); } } I want to use HashSet<IdenNode> with mind that two elements of it are same(Equal) if and only if their id.Names are Equal. So, I'm gonna override Equals and GetHashCode like next: public override bool Equals(object obj) {

问题 This question already has answers here : Java object equals method not work (5 answers) Closed 3 years ago . I have a custom class called Card public class Card implements Serializable, Comparable<Card>{ private static final long serialVersionUID = 100L; private Rank rank; private Suit suit; public Card(Rank rank, Suit suit){ this.rank = rank; this.suit = suit; } public enum Rank{ TWO(2), THREE(3), FOUR(4), FIVE(5), SIX(6), SEVEN(7), EIGHT(8), NINE(9), TEN(10), JACK(10), QUEEN(10), KING(10),

问题 I have a list in that list I created an object. By using the contains() method, I want to check whether the object already exists or not. For that, I override the equals() method. Everything is perfect upto this. But when I try to do the same thing for String and int the equals() override doesn't not work. Why is it like this? I just posted some sample code for reference. public class Test { private int x; public Test(int n) { x = n; } public boolean equals(Object o) { return false; } public

问题 In Java to compare two objections for equality, you must implement both the equals method and the hashCode method. I need to compare two BSTs for equality. How do I implement the hashCode method in such a case? Now, implementing the hashCode on the Node class is simple enough: imagine my data is int . But I cannot just add the values of the node to check if the trees are equal. So how do I do it? Has anyone done this successfully? I am thinking of many different things that I can do, but I am

问题 Lets see we have 2 references to instances of a user-defined class, a and b in Java. Can there ever be a situation where a == b but a.equals(b) return false? 回答1: Sure! The implementation of .equals() is completely up to the class, so I could write: class Foo public boolean equals(Object other) { return false; } } Now it doesn't matter what two instances you pass — even the exact same instance twice — I'm always going to say they're not equal. This particularly setup is silly, but it

问题 I was trying to use set. so i tried this way HashSet set=new HashSet(); Points p1 = new Points(10, 20); Points p2 = new Points(10, 20); System.out.println(set.add(p1)); // output true System.out.println(set.add(p2)); // output false I know my first output will be true and second will be false as Set will not allow duplicate elements. And, i also know Set achieve this by using equals(Object o) method. Which comes from java Object class with following signature. public boolean equals(Object o)