Array Hacks

Hack 1

import java.util.*;
// create ArrayLists that satisfy the following
public class Turtle{
    public String height;
    public Turtle(String height){
        this.height = height;
    }
    public String toString() {
        return height;
    }

}
// a) that stores Boolean values
ArrayList<Boolean> Arraylist1 = new ArrayList<Boolean>();
Arraylist1.add(true);
System.out.println(Arraylist1.toString());

// b) that stores Turtle Objects
ArrayList<Turtle> Turtle1 = new ArrayList<Turtle>();
Turtle turtle = new Turtle("5");
Turtle1.add(turtle);
System.out.println(Turtle1.toString());

// c) that initializes with 10 Strings

ArrayList<String> Arraylist1 = new ArrayList<String>(10);

[true]
[5]

Hack 2

import java.util.ArrayList;

public class Hack2 {
    public static void main(String[] args) {
        ArrayList<Integer> randomNumbers = new ArrayList<Integer>();
        randomNumbers.add(1);
        randomNumbers.add(4);
        randomNumbers.add(7);
        randomNumbers.add(12);
        randomNumbers.add(23);
        System.out.println("ArrayList: " + randomNumbers);

        randomNumbers.remove(1);
        randomNumbers.add(18);
        System.out.println(randomNumbers.size());
        System.out.println("ArrayList: " + randomNumbers);
    }
}
Hack2.main(null);

ArrayList: [1, 4, 7, 12, 23]
5
ArrayList: [1, 7, 12, 23, 18]

Hack 3

public class Hack3 {
    public static void main(String[] args) {
        ArrayList<Integer> values = new ArrayList<Integer>();
        values.add(1);
        values.add(4);
        values.add(7);
        values.add(12);
        values.add(23);
        System.out.println("ArrayList: " + values);
        
        int total = 0;

            for (int i=0; i < values.size(); i++) {
                total += values.get(i);
            }
        System.out.println(total);
    }
}
Hack3.main(null);

ArrayList: [1, 4, 7, 12, 23]
47

Hack 5

public class Hack3 {
    public static void main(String[] args) {
        ArrayList<Integer> values = new ArrayList<Integer>();
        values.add(1);
        values.add(4);
        values.add(7);
        values.add(12);
        values.add(23);
        System.out.println("ArrayList: " + values);
        
        System.out.println("even");
 
            for (int i=0; i < values.size(); i++) {
                if (values.get(i) % 2 == 0) {
                    System.out.println(values.get(i));
                }
               
            }
        System.out.println("odd");
            for (int i=0; i < values.size(); i++) {
                if (values.get(i) % 2 == 1) {
                    System.out.println(values.get(i));
                }
               
            }
      
    }
}
Hack3.main(null);

ArrayList: [1, 4, 7, 12, 23]
even
4
12
odd
1
7
23

Hack 6

int[][] array = {{1,2,3,4},{5,6,7,8},{9,10,11,12},{13,14,15,16}};
for (int r=0; r< array.length; r++) { 
    for (int c = 0; c < array[0].length; c++) { 
        System.out.print(array[r][c] + " ");
    }
    System.out.println();
}

1 2 3 4 
5 6 7 8 
9 10 11 12 
13 14 15 16