Prerequisite : Overloading
Java can distinguish the methods with different method signatures. i.e. the methods can have same name but with different parameters list (i.e. number of the parameters, order of the parameters, and data types of the parameters) within the same class.
- Overloaded methods are differentiated based on the number and type of the parameters passed as an arguments to the methods.
- You can not define more than one method with the same name, Order and the type of the arguments. It would be compiler error.
- The compiler does not consider the return type while differentiating the overloaded method. But you cannot declare two methods with the same signature and different return type. It will throw a compile time error.
If both methods have same parameter types, but different return type, then it is not possible. (Java SE 8 Edition, §8.4.2)
Why do we need Method Overloading ??
If we need to do same kind of the operation with different ways i.e. for different inputs. In the example described below, we are doing the addition operation for different inputs. It is hard to find many different meaningful names for single action.
Different ways of doing overloading methods
Method overloading can be done by changing:
- The number of parameters in two methods.
- The data types of the parameters of methods.
- The Order of the parameters of methods.
Method 1: By changing the number of parameters.
sum of the two integer value :3 sum of the three integer value :6
Method 2: By changing the Data types of the parameters
sum of the three integer value :6 sum of the three double value :6.0
Method 3: By changing the Order of the parameters
geekName :Mohit Id :1 geekName :shubham Id :2
What happens when method signature is same and the return type is different?
The compiler will give error as the return value alone is not sufficient for the compiler to figure out which function it has to call. More details:Java Language Specification: §8.4.2.
Only if both methods have different parameter types (so, they have different signature), then Method overloading is possible.
16: error: method add(int,int) is already defined in class Addition public double add(int a, int b) ^ 1 error
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