Polymorphism in java can be implemented by using method overloading & method over riding. Method overloading is a process of defining many methods with the same name. But parameter must be different. A method acts upon different sets of parameters. But, basic operation is same.
1. when many methods are performing same operations. It would be easy to call same method with different types of arguments.
2. we can overriding many methods and remember them for the same operation.