What is Method Overloading in Java? An Example

What is method overloading in Java?
Method overloading in Java is an object-oriented programming concept that allows a programmer to declare two methods of the same name but with different method signatures, like change in the argument list or change in the type of argument. Method overloading is a powerful Java programming technique to declare a method that does a similar job but with a different kind of input. One of the most popular examples of method overloading is the System.out.println() method whose job is to print data on the console. This method is overloaded to accept all kinds of data types in Java. 

You have the println() method which takes String, int, float, double, or even char in output. All of those methods are collectively referred to as an overloaded method in Java.

You should also know that difference between method overloading and overriding is also a popular Java interview question. In the next section, we will some important points about method overloading in Java and then a simple example of how to overload a method in Java.

By the way, if you are new to Java and object-oriented programming then I also recommend you to join a comprehensive Java course like The Complete Java Masterclass on Udemy to learn in a more structured way. This 80-hour long course is the most updated and comprehensive and you can get it for just $10 on Udemy sales now. 




Properties of method overloading in Java

1) Overloaded methods are bonded using static binding in Java. Which occurs during compile time i.e. when you compile a Java program. During the compilation process, the compiler bind method calls to the actual method.

2) Overloaded methods are fast because they are bonded during compile time and no check or binding is required during runtime.

3) Most important rule of method overloading in Java is that two overloaded methods must have a different signature

Here is an example of what does method signature means in Java:
  • A number of arguments to a method are part of the method signature.
  • Type of argument to a method is also part of the method signature
  • Order of argument also forms part of the method signature provided they are of a different type.
  • The return type of method is not part of the method signature in Java.
These are some important points to remember while working in Java or going for Java interviews. If you need more object-oriented questions I suggest you checkout Grokking the Object-Oriented Design Interview course form Educative. 

What is method overloading in Java - Example Tutorial




Method Overloading Example in Java

Here is a list of method and there a corresponding overloaded method with the reason that How they are overloaded :

Original method :

public void  show(String message){
      System.out.println(message);
}

Overloaded method: number of argument is different

public void  show(String message, boolean show){
      System.out.println(message);
}

Overloaded method: type of argument is different

public void  show(Integer message){
      System.out.println(message);
}


Not an Overloaded method: the only return type is different

public boolean show(String message){
      System.out.println(message);
      return false;
}

In the summary method, overloading means multiple methods with the same name but with a different signature. remember return type is not part of the method signature. method overloading is also completely different from method overriding which is a similar concept and we will see in the next article.

That's all on what is method overloading in Java, let me know if you have any question related to How to overload a method in Java.

Further Learning
SOLID Principles of Object-Oriented Design
Absolute Introduction to Object-Oriented Programming in Java
Java - Object-Oriented Programming [For Absolute Beginners]


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6 comments:

  1. Method overloading in any programming language, including Java will work fine if:

    - the two variants have a different number of parameters
    - the two variants have the same number of parameters but the types are unrelated

    In both cases, the overloaded method should logically consist of the same name and operation, but with different kind of inputs.

    For example, this is fine:

    LocalTime.of(int hour, int minute)
    LocalTime.of(int hour, int minute, int second)

    as both the method are actually creating time but with different set of input, so name of() is valid and there is on confusion between these two methods.

    Here is another example, which is also fine:
    Bundle.of(String[] data)
    Bundle.of(Iterable data)

    (there is no possible confusion between the types, the overload method is providing flexible input handling for callers, both methods must perform the same logical task and that's why same name)

    But if you have the same number of parameters and related types, then it's a big problem. That should be avoided as it causes users great difficulty in figuring out which method is called
    If two overloaded methods actually behave differently, then they also fail the rule that overloads should be logically equivalent.

    ReplyDelete
  2. hmm..it looks like the same parameters to,,i mean in the local time part.

    any other example?

    ReplyDelete
  3. Thanks for this tutorial

    You told overloading example is System.out.println(). So can you explain different argument types in println() in detailed explanation is required.

    ReplyDelete
  4. public Double add(int a, double b) {
    return a+b;
    }

    public Double add(double a, int b) {
    return a+b;
    }

    Is this method overloading or not?

    ReplyDelete
  5. yes, as sequence of arguments are interchanged

    ReplyDelete

Feel free to comment, ask questions if you have any doubt.