Methods

Methods.java

import java.util.Arrays;

public class Methods {

    public static void main(String[] args) {

        // Methods are just functions that belong to a particular class

        // Methods are sub-routines. Reusable code.
        // Method have parameters, are called with arguments
        int y = calc(1, 1);
        print("y="+y);

        // Methods can be 'over-loaded'
        double x = calc(1.0, 2.0);
        print("x="+x);

        // Methods can be code abbreviations
        String grade = getGrade(76);
        print(grade);

        // Methods calls are pass-by-value!!
        // http://javadude.com/articles/passbyvalue.htm
        int g = 90;
        passByValueDammit(g);
        System.out.println(g);

        // Methods are values! Java 8 only
        Arrays.asList("peter", "anna", "mike", "xenia").forEach(System.out::println);
    }

    // x and y are 'formal parameters'
    public static int calc(int x, int y) {
        return (x + y) * 20 % 3;
    }

    // overload! note that return type is not enough!
    public static double calc(double x, double y) {
        return (x + y) * 20.0 % 3.0;
    }

    public static void passByValueDammit(int x) {
        x = x * 2;
    }

    // returning 'void' means side-effect!
    // void is the lack of a type. Different than null!
    public static void print(String printMe) {
        System.out.println(printMe);
    }

    public static String getGrade(int testScore){
        String grade;

        if (testScore >= 90 && testScore <= 100) {
            grade = "A";
        } else if (testScore >= 80) {
            grade = "B";
        } else if (testScore >= 70) {
            grade = "C";
        } else if (testScore >= 60) {
            grade = "D";
        } else {
            grade = "F";
        }

        return grade;
    }



}