1.9 HW Hacks

Popcorn Hack 1

public class PopcornMax {
    // TODO: write int version of max
    public static int max(int x, int y) {
        if (x > y) {
            return x;
        } else {
            return y;
        }
    }

    // TODO: write double version of max
    public static double max(double x, double y) {
        if (x > y) {
            return x;
        } else {
            return y;
        }
    }

    public static void main(String[] args) {
        System.out.println(max(3, 9));      // expected: 9
        System.out.println(max(-2, -7));    // expected: -2
        System.out.println(max(3.5, 2.9));  // expected: 3.5
        System.out.println(max(2, 2.0));    // should call double version → 2.0
    }
}


PopcornMax.main(null);

9
-2
3.5
2.0

Popcorn Hack 2

public class PopcornPrint {
    // TODO: write print(int n)
    public static void print(int n) {
        System.out.printf("int:%d\n", n);
    }

    // TODO: write print(String s)
    public static void print(String s) {
        System.out.printf("str:%s\n", s);
    }
    

    public static void main(String[] args) {
        print(42);          // expected: int:42
        print("hello");     // expected: str:hello
        print('A' + "!");   // char + String → String → expected: str:A!
    }
}


PopcornPrint.main(null);

int:42
str:hello
str:A!

Short Answers

1. int sum(int a, int b) and double sum(int a, int b) cannot both exist as they have the same method signature of sum(int, int).
2. The difference between a parameter and argument is that a parameter are placeholders for functions of variables it can accept, while arguments are real values passed into functions.

Coding Tasks

public class Main {
    public static int abs(int x) {
        return (x < 0) ? x *= -1 : x;
    }
    
    public static double abs(double x) {
        return (x < 0) ? x *= -1 : x;
    }

    public static long abs(long x) {
        return (x < 0) ? x *= -1 : x;
    }
    
    public static String concat(String a, String b) {
        return (a + b);
    }

    public static String concat(String a, int n) {
        return a.repeat(n);
    }
    
    static void show(int x) {
        System.out.println("int");
    }

    static void show(double x) {
        System.out.println("double");
    }

    static void show(long x) {
        System.out.println("long");
    }

    public static void main(String[] args) {
        show(7);
        show(7L);
        show(7.0);

        System.out.println(abs(-7.5));
        System.out.println(concat("Hello", 5));
    }
    
}

Main.main(null);

int
long
double
7.5
HelloHelloHelloHelloHello