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Because, if two objects are supposed to be equal as per the equals() method, then the value returned by the hashCode() method must also be the same. This will not be the case if you override only the equals method and this can have some confusing effects when using those objects with hash related collections. So it is always a good idea to override the hashCode() method if you are providing an implementation for the equals method.
What else can I help you with?
Why can't method override be used without inheritance?
Overriding a method means that you are replacing an existing or virtual method that has already been defined in the parent object class, so without using inheritance, there can be no existing method to override.
What is the hashCode method and what is the purpose of this method in Object?
The hashCode method is used to create a unique identification number to describe the state and type of an object.The Java API description of the method is:Returns a hash code value for the object. This method is supported for the benefit of hashtables such as those provided by java.util.Hashtable.The general contract of hashCode is:Whenever it is invoked on the same object more than once during an execution of a Java application, the hashCode method must consistently return the same integer, provided no information used in equals comparisons on the object is modified. This integer need not remain consistent from one execution of an application to another execution of the same application.If two objects are equal according to the equals(Object) method, then calling the 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 Object.equals(java.lang.Object) method, then calling the hashCode method on each of the two objects must produce distinct integer results. However, the programmer should be aware that producing distinct integer results for unequal objects may improve the performance of hashtables.As much as is reasonably practical, the hashCode method defined by class Object does return distinct integers for distinct objects. (This is typically implemented by converting the internal address of the object into an integer, but this implementation technique is not required by the JavaTM programming language.)
What is the difference between overloading and overriding methods in object?
Here are some of the most common differences between both of them. If you are working in Java for more than 1 year, you might be familiar with all of them but any way its good revision: 1) First and major difference between Overloading and Overriding is that former occur during compile time while later occur during runtime. 2) Second difference between Overloading and Overriding is that, you can overload method in same class but you can only override method in sub class. 3) Third difference is that you can overload static method in Java but you can not override static method in Java. In fact when you declare same method in Sub Class it's known as method hiding because it hide super class method instead of overriding it. 4) Overloaded methods are bonded using static binding and Type of reference variable is used, while Overridden method are bonded using dynamic bonding based upon actual Object. 5) Rules of Overloading and Overriding is different in Java. In order to overload a method you need to change its method signature but that is not required for overriding any method in Java.
Can you override an instance method and make it final?
No. Once a method is declared final in a class, no derivative of that class can override that method.
Is overriding a dynamic polymorphism in c plus plus or not?
In C++, overriding and function, method, or operator is a different thing than (dynamic) polymorphism, so overriding a polymorphic method is almost entirely possible.
How is hiding method different from overriding method in c sharp?
Hiding means a class cannot see the definition. Overriding implies that a class must see that to "override"
Why can't method override be used without inheritance?
Overriding a method means that you are replacing an existing or virtual method that has already been defined in the parent object class, so without using inheritance, there can be no existing method to override.
What is the hashCode method and what is the purpose of this method in Object?
The hashCode method is used to create a unique identification number to describe the state and type of an object.The Java API description of the method is:Returns a hash code value for the object. This method is supported for the benefit of hashtables such as those provided by java.util.Hashtable.The general contract of hashCode is:Whenever it is invoked on the same object more than once during an execution of a Java application, the hashCode method must consistently return the same integer, provided no information used in equals comparisons on the object is modified. This integer need not remain consistent from one execution of an application to another execution of the same application.If two objects are equal according to the equals(Object) method, then calling the 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 Object.equals(java.lang.Object) method, then calling the hashCode method on each of the two objects must produce distinct integer results. However, the programmer should be aware that producing distinct integer results for unequal objects may improve the performance of hashtables.As much as is reasonably practical, the hashCode method defined by class Object does return distinct integers for distinct objects. (This is typically implemented by converting the internal address of the object into an integer, but this implementation technique is not required by the JavaTM programming language.)
What is overriding in c?
Overriding relates to derived classes, where the derived class provides a new implementation for a method declared in the base class. The override is said to be a more-specialised implementation of the base class method, which is itself described as being a generic method. However, the derived class method can still call the base class method, if required.When the designer of a class can predict that their class will be derived from, they will normally provide virtual methods. These methods are expected to be overridden by the derived class. Overriding a non-virtual method can have side effects if the method is also overloaded. Overriding just one overloaded method will effectively hide all the other overloads in the base class, which may be undesirable.
What is the difference between overloading and overriding methods in object?
Here are some of the most common differences between both of them. If you are working in Java for more than 1 year, you might be familiar with all of them but any way its good revision: 1) First and major difference between Overloading and Overriding is that former occur during compile time while later occur during runtime. 2) Second difference between Overloading and Overriding is that, you can overload method in same class but you can only override method in sub class. 3) Third difference is that you can overload static method in Java but you can not override static method in Java. In fact when you declare same method in Sub Class it's known as method hiding because it hide super class method instead of overriding it. 4) Overloaded methods are bonded using static binding and Type of reference variable is used, while Overridden method are bonded using dynamic bonding based upon actual Object. 5) Rules of Overloading and Overriding is different in Java. In order to overload a method you need to change its method signature but that is not required for overriding any method in Java.
Can you override an instance method and make it final?
No. Once a method is declared final in a class, no derivative of that class can override that method.
What is a example of override?
An override occurs when you create a method of the same name as the one in the parent/super class. Ex: public class A { ..... public String getName(){ } ..... } public class B extends A { ..... public String getName(){ } ..... } Here class B which is the child class of A also declares a method of the same name as in the parent class. This is overriding...
Is overriding a dynamic polymorphism in c plus plus or not?
In C++, overriding and function, method, or operator is a different thing than (dynamic) polymorphism, so overriding a polymorphic method is almost entirely possible.
What is function overriding in Java?
Method overriding is similar to method overloading, with a small difference. In overriding, a method in a parent class is overridden in the child class. The method in the child class will have the same signature as that of the parent class. Since the method in the child class has the same signature & name as the method of its parent class, it is termed as overriding. In situations where you may have to explicitly call the parent class method you can use the "super" keyword and for explicitly calling the current objects method you can use the "this" keyword.
Difference between Method overloading and method overriding in C plus plus?
Yes. Any base class method that is declared virtual can be overridden by a derived class. Overriding a method that is not declared virtual can still be called, but will not be called polymorphically. That is, if you call the base class method, the base class method will execute, not the override. To call a non-virtual override you must call it explicitly.
What is the difference between reference and hash code in java?
Cat oldCat = new Cat(); Cat newCat = new Cat(); Cat oldCatRef = oldCat; In the above example, oldCat and oldCatRef are references to the same object. Since they refer to the same object, their hashcodes will be equal. But oldCat and newCat do not refer to the same object. They are references to two different objects. But they might have the same hashCode based on their implementation. hashCode is simply a method in Object class which you can override.
Is method overridding is polymorphism?
Yes. Method Overriding is a form of Polymorphism.Overridden MethodsAny time you have a class that inherits a method from a superclass, you have the opportunity to override the method (unless, as you learned in the earlier chapters, the method is marked final). The key benefit of overriding is the ability to define behavior that's specific to a particular subclass type. The following example demonstrates a Porsche subclass of Car overriding the Car version of the drive() method:public class Car {public void drive() {System.out.println("Generic Car Driving Generically");}}class Porsche extends Car {public void drive() {System.out.println("Porsche driving Full Throttle");}}
