Hii ,friend's
Today I will expain you about the diffrence between Method Declaration and method definition.
In Method Declartion you can declare somthing like [public void my function();] here myfunction is the name of method. And In Method defintion you can put complete information like [public void emp();], in this emplyee method, you can put complete details like name , id, phone number etc. See the below examples it will clearly describe you the diffrence between Method Declaration and method definition.

Step(1) Method Declaration-Method declaration is only declare a method name

public void myfunction();  //method name myfunction

Step(2)Method definition -A declaration that reserves storage (for data) or provides implementation (for methods).

Syntax-

 public <returnType> <methodName>() {
    <bodyOfMethod>
}

Ex-1

List l;              // declaration 
l = new ArrayList(); // definition