hashcode and equals in java

Value) is returned ). If we want to get the expected results, we need to rewrite the toString method. [Java]Package mark. demo;Public class EnumDemo {Public static void main (String [] args ){For (Color color: Color. values ()){System. out. println (color );}}Public enum Color {RED ("red color", 0), GREEN ("green color", 1), BLUE ("blue color", 2), YELLOW ("Yellow color", 3 );Color (String name, int id ){_ Name = name;_ Id = id;}Private String _ name

I need to record some of the things I saw in Sunday, or I'll forget about them.Hashcode, equals:1) Each Java object has the Hashcode and equals methods.The ultimate Java class is the object class, so how does the object class label itself, that is, how the class of object di

* Public voidSetblood (intblood) { $ This. Blood =Blood;Panax Notoginseng } - the PublicPerson (intHeightintWeightintAgeintblood) { + This. Height =height; A This. Weight =weight; the This. Age =Age ; + This. Blood =Blood; - } $ $ @Override - Public Booleanequals (Object o) { - the if( This. hashcode () = =O.hashcode ()) { - return true;Wuyi } the

When learning Java basic data types and complex data types, especially equals () "= =" and the Hashcode () part, not very understand, also stayed a long time, finally a bit of a look.To understand equals () "= =" and Hashcode (), it's a good idea to first understand the heap

In Java, equals and hashcode have design requirements, equals equal, then hashcode must be equal, or vice versa. Why is there such a requirement? In the collection, such as HashSet, the object required to be placed can not be repeated, how to determine it? The

(adouble); Result= Prime * result + (int) (tolong ^ (Tolong >>> +)); Result= Prime * result +Aobject.hashcode (); Result= Prime * result +Intshashcode (ints); Result= Prime * result +Unitshashcode (units); returnresult; } Private intIntshashcode (int[] aints) { intresult = -; for(inti =0; i ) Result=Panax Notoginseng* result +Aints[i]; returnresult; } Private intUnitshashcode (unit[] aunits) {intresult = -; for(inti =0; i ) Result=Panax Notoginseng* result +Aunits[i].

1.equals () In the beginner Java, many people will say that when comparing objects, = = is the comparison of the address, equals () is the content of the comparison object, who said? Look at the definition of the Equals () method in the object class: public　boolean　equals

relation on objects; * That's, for any non-null reference values {@code x} and * {@code y}, this is returns {@code true} if and only * If {@code x} and {@code y} refer to the same object * ({@code x = = y} has the value {@code true}). * * The It is generally necessary to override the {@code hashcode} * Method whenever this and is overridden, and so as to maintain the * General contract for the {@code hashc