equals

问题 Lovely equals and hashcode, all the theory is here and also here I have taken the decision to use the auto-generated id within equals() and hashcode() in a number of my hibernate entity/domain objects. However, a number of websites say you should never do this due to the risk of persisting an object to the database for the first time whilst it is in the process of being compared or using hashcode. My point of view is that in most use cases this is much more unlikely than any other field being

问题 So, I have an interface with a bunch of methods that need to be implemented, the method names are irrelevant. The objects that implement this interface are often put into collections, and also have a special toString() format that I want them to use. So, I thought it would be convenient to put hashCode(), equals(), and toString() into the interface, to make sure that I remember to override the default method for these. But when I added these methods to the interface, the IDE/Compiler doesn't

问题 I'm trying to write an equals method for objects that compares their fields and return true if they're equal. private int x, y, direction; private Color color; public boolean equals(Ghost other){ if (this.x == other.x && this.y == other.y && this.direction == other.direction && this.color == other.color) return true; else return false; } What could be wrong with this? 回答1: Since color appears to be a Color, that's a class, and therefore a reference type, which means you need to use equals()

问题 I have the following code: object val1 = 1; object val2 = 1; bool result1 = (val1 == val2);//Equals false bool result2 = val1.Equals(val2); //Equals true What's up with that? Is the only way to fix this to go with .Equals() method? 回答1: The operator == is static, not virtual, so the behaviour is determined by the static type and not the runtime type. The default implementation for == on objects of reference type is to compare the references (although types can implement a different behaviour,

问题 Hashcode() and equals() concept is 1) If two Objects are equal according to equal(), then calling the hashcode method on each of those two objects should produce same hashcode. and other one is 2) It is not required that if two objects are unequal according to the equal(), then calling the hashcode method on each of the two objects must produce distinct values. I tried and understood first one and this is the code for first point. public class Test { public static void main(String[] args) {

问题 How should I implement hashCode() and equals() for the following class in Java? class Emp { int empid ; // unique across all the departments String name; String dept_name ; String code ; // unique for the department } 回答1: in Eclipse right mouse click-> source -> generate hashCode() and equals() gives this: /* (non-Javadoc) * @see java.lang.Object#hashCode() */ @Override public int hashCode() { final int prime = 31; int result = 1; result = prime * result + (code == null ? 0 : code.hashCode()

问题 I want to write an if/else statement that tests if the value of a text input does NOT equal either one of two different values. Like this (excuse my pseudo-English code): var test = $("#test").val(); if (test does not equal A or B){ do stuff; } else { do other stuff; } How do I write the condition for the if statement on line 2? 回答1: Think of ! (negation operator) as "not", || (boolean-or operator) as "or" and && (boolean-and operator) as "and". See Operators and Operator Precedence. Thus: if

问题 This question already has answers here : Using GetHashCode to test equality in Equals override (8 answers) Closed 6 years ago . given the person class: class person { public string name; public int age; } say, i override the class person`s GetHashCode method: public override int GetHashCode() { unchecked { hashCode = 17; // ...some code here... } return hashCode; } and based on msdn`s instruction, i also need to override the Equality, so i did this: public override bool Equals(object obj) { /

问题 I get a string form a list and try to compare it with some strings in the values and then do some stuff for(int i=0; i<sizeOfList; i++){ String LIST_TITLE; LIST_TITLE = list_title.get(i); //the List list_title includes some strings if(LIST_TITLE.equals(R.string.percentbattery)) { //do stuff Log.d("EQUAL!","" + LIST_TITLE); } else if(LIST_TITLE.equals(R.string.screenrecorder) == true) { //do stuff Log.d("EQUAL!","" + LIST_TITLE); } else if(LIST_TITLE.equals(R.string.eightsms) == true) { //do

问题 I have Hashmap,how to override equals method for the hashmap? Thanks. 回答1: if you want you can do: HashMap<String, String> map = new HashMap<String, String>(){ @Override public boolean equals(Object o) { // TODO comparison here return super.equals(o); } }; map.equals(new HashMap<String, String>()); 回答2: In HashMap already equals() method is overrriden.If you want to override object class equals() method eclipse shortcut key--->alt+shift+s+v Select the equals method click on ok. 回答3: You will