Learner

Objects have special kind of method called a constructor. A constructor is an optional method that is called when a new instance of an object is created with the new keyword. Constructors are used to initialize the fields of the new object instance. A constructor looks like a method except that it has no return data type (including void) and has the same name as the class. A constructor can have a parameter list and a class can have more than one constructor by varying the parameter list.

We are going to wrap-up the unit on methods with several resources for you to view:

Here is a video about methods. This video is a good introduction to methods. However the definition of the static keyword in this video is incorrect. Please ignore the discussion of static for now as we will explore static later in this curriculum.

Remember that we mentioned that a method's name and parameter list are called the method's signature and this signature is how Java identifies methods. So it follows that while methods with a different name are definitely not the same method, methods with the same name and different parameter lists are also not the same method. This allows you to use different parameter lists to create variations of a method single name. This is called overloading. Here is an example of overloading:

While methods can perform their function without returning any data to the calling code, a common use of methods is to perform some process or computation and return a result to the caller. When a method does not return a value, the return data type is called void. An example of a method that would have no return value would be a motor’s setPower(x) function. When we use that function, we aren’t looking for the code to compute something and give us the result, but we are asking the method to make some change in the robot hardware’s current running state.

Methods are reusable code blocks that are only executed when called from another location in your program. Methods are also called functions or subroutines. For our purposes, these names mean same thing. In other languages, the names may mean something a bit different.