CSC 172 Lab Java Functional Interface

JavaFunctionalInterface.md

Note on Java Functional Interface

If you read this, and still don't understand what is the syntax, read on:

A Java Function is like a method, but is more powerful than a method. For the purpose of this lab, you would only need to know that a fucntion, is like a method.

At the meantime, a Function is an Object (instance of a class), and so to start coding up your Function, you need to declare a Function, just like any other Object.

When you declare an Object, you do this:

Type name = //blah

And so, when you declare your function, it looks like this:

Function<paramType, returnType> name

Here, the type is a Function that takes in parameter of type paramType and returns an Object of type returnType

And so, if your Function takes in a Character array and spits out a Character, your type looks like this:

Function<Character[], Character> findMax

And after declaring the Function, you would need to define it. To define a Function, you would need to specify the input parameter and how the Function is going to return a value.

Function<paramType, returnType> name = param -> { //do stuff };

And so your function would look like this:

Function<Character[], Character> findMax = charArr -> { 
    //Do stuff 
    return maxChar; 
};

Note that, your "do stuff" part may take several lines, and must include a return statement, just like your other methods.

However, since Function is an Object, you cannot call the Function as you call a method. Instead, you call the instance method .apply(param) to apply the Function on the given parameter. It will look like this:

findMax.apply(charArr);

Hope you find this useful and good luck!

Sifan Ye