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Alternatives to Inner Classes

Only had one place in the code where we created the iterator subclass and nowhere where its name is used. Might be annoying to keep creating a class each time we need one object somewhere in the code

  • An anonymous class is an inner class without a name.
  • Instead of giving a class a name and saying that the class extends/implements some class, name the super-class and then give the implementation of the changes.

Lambdas

  • Simpler syntax for an anonymous class when it sub classes : an interface which has only one method
  • Both of these are important!
  • Give it an implementation of the method
    • Only one method on the interface so it knows the method name
    • Knows the return type
    • Knows the parameters types
  • Use -> operator.
  • To the left of the -> are the parameters
  • To the right is the expression to evaluate to return the result value

Variable Capture​

  • Lambda expressions can capture final(constant) variables from the surroundings. This kind of puts a copy of this variable inside the Lambda.
  • Can also use member variables, so it can capture the 'this' object

Expressions​

Can think of them as a way of wrapping up a function in an object Once have an object, we keep an object reference to it Can use sub-type polymorphism and treat it as the base-class. Can access member variables or final local variables

Summary​

If need an object to handle a function, could:

  • Create an object of a new top-level class
  • Create an object of an inner class
  • Create an object of an inner class
  • Create an object of an anonymous class
  • Create a Lambda