Overriding and overloading are concepts you need to understand as a programmer. These concepts are essential when programming in Java, but other languages also use these concepts. You need to understand the difference between overloading and overriding to determine which approach is best for what you want to accomplish.
Polymorphism is an important concept in object-oriented programming. It refers to the fact that an object can be processed differently depending on the data type that is available for this object. In some cases, the object class will indicate how the object is processed.
Polymorphism can either be static or dynamic. Overloading is the technique you would use for static polymorphism while overriding is the dynamic approach.
Polymorphism is a crucial concept since it helps you save time when coding. Without polymorphism, you would have to work with several different methods. Being able to create different variations of a method and invoking a specific version of a method in your code helps you keep your code short and concise.
What Is Overloading?
Java is a programming language that gives you the possibility to invoke a method at any time in your code by simply using the method’s name. You can use built-in methods or define a new method if you need to perform a task that isn’t covered by a built-in method.
Overloading allows you to use a method name and to have different signatures associated with this name. The version of the method that is executed depends on the parameters available.
There are a few rules to follow when using overloading in Java. You can have different versions of the same method exist in the same class.
When creating the different definitions of a method, you can use different types of parameters, have a different number of parameters, and change the order of the parameters.
Overloading is a concept that also exists in C++. You can overload a function or an operator.
If you need to overload a function, start by creating two or more functions with the same name in the same scope. Each function needs to have a different definition. Just like with Java, you can use different types of arguments or a different number of arguments. Keep in mind that you can’t have different return types.
Note that the purpose of overloading is to create different versions of a method without changing the method behavior. This is the solution you would choose to apply the same behavior to objects parameter variations. If you need to create a new behavior, using a different method would make more sense.
You can also overload operators in C++. This only works with built-in operators and not all of them can be overloaded. Operators that can’t be overloaded include the conditional operator, member selection operators, object size and object type information operators, and the scope resolution operator.
When you overload a function or an operator in C++, your code compiler is going to look at the different argument types that were used to call the function or the operator. The compiler will choose the definition of the function or operator with parameter types that correspond to the data used when the function or operator was called.
Remember that overloading is the static approach to polymorphism. This means the correct method signature is selected when the code is compiled.
You can use overloading with different return types, different access modifiers, and different checked and unchecked exceptions. There are fewer restrictions that apply to overloading when it comes to defining the different versions of your method, function, or operator.
What Is Override?
Overriding is the dynamic approach to polymorphism. With this method, the correct method definition is selected at runtime.
The main difference between overloading and override is that override is used to create different definitions of a method that is inherited by a class. Overloading is less restrictive since this method allows you to have different definitions of a method so a relevant definition can be executed depending on the data available.
Creating a subclass in Java means that the methods that apply to the superclass are inherited by the subclass. Overriding gives you the possibility to define a new behavior for the subclass, so the method inherited from the superclass doesn’t apply.
Override is often used to remove methods inherited by the Object class. For instance, the toString() method is often overridden so that programmers can create a new string representation of the object they are working with.
Note that final methods that apply to the Object class can’t be overridden. This is true for the getClass() method.
Some Object class methods can be overridden, but the new method definition can lead to an undesirable outcome if you don’t take the original purpose of the method into consideration. For instance, the hashCode() method generates a number for each object. This hash code can be used to refer to a specific object inside of a data structure. Overriding the hashCode() method means you need to create a new way to refer to each object.
Overriding works by replacing an existing method definition with a different one if an object belongs to a subclass.
You need to keep a few rules in mind when using override in java. Once you have created an alternative definition, you can invoke the original version by using the super keyword.
Keep in mind that overriding only works with methods. You can’t use this approach with constructors. Besides, overriding only works if you have an architecture with a superclass and one or more subclasses.
Because overriding replaces the definition of a method that is inherited, you can only use it if a method is inherited.
There are some restrictions regarding the argument list of the new method. The argument list of the new method needs to be identical to the argument list of the original method. You can’t have different parameter types, can’t have more or fewer parameters, and can’t change the order of the parameters.
You can either use the same return type or choose a new return type that is categorized as a subtype of the original return type.
There are also restrictions regarding the access level of the new method. Overriding doesn’t let you create a new method that is more restrictive. If you used a public method for the superclass, the overridden version of the method can’t be private.
If the subclass is located in the same package as the superclass, you can override a method that isn’t set to private or final. However, if the classes are in different packages, you can only use override with methods that are set to public or protected.
You should also know that you can’t use broader checked exceptions for the new method.
When To Use Overloading And Overriding
Overloading and overriding help you save time. Polymorphism lets you use different definitions of a method instead of creating two different methods. You need to use polymorphism whenever you need different outcomes for a method or expect to have objects with different parameters that might not correspond to the original definition of a method.
You would use overloading when there isn’t a class relationship between the objects you are working with. Overloading makes sense when you need a method that can be applied to objects with a varying range of parameters.
There is more flexibility in what you can do with your new method definition, and overloading allows you to use a method for a wide range of object parameters. You can use the same method name for objects with different parameter types, a different number of parameters, and with variations in the order of the parameters.
Overriding is the method you would choose with objects that have a superclass and subclass or child class relationship. You can’t use overriding if this relationship doesn’t exist.
The purpose of overriding is to get rid of a method that is inherited by the subclass or to modify what this method does.
There are a lot more rules to follow when using overriding. The new method definition needs to have the same arguments, and either uses the same return type or a subclass of the original return type. Note that you might not be able to use a subclass of the original return type if you are working with a version of Java that is older than Java 5.
An override is an approach you can only use in a specific scenario and even though there are limitations regarding the new method, this is a useful functionality since not all inherited methods are desirable. Overloading can be applied in a wider range of scenarios and gives you more possibilities when it comes to redefining a method.
You should now have a better understanding of overloading and overriding in Java. Both techniques allow you to use polymorphism for methods, but each technique is used in a different scenario and comes with a different set of rules.