Key Learnings

Arrays have a fixed size, while Arraylists do not.

Can make arrays pre-initialized or with constructors.

ArrayIndexOutOfBoundsException thrown can happen when using loops to access array elements

Hack 1

int[] arrayOne = {1, 3, 5, 7, 9};

for (int num : arrayOne) {
    if (num % 2 == 0) {
        System.out.println(num);
    } 
}

Hack 2

// B

Hack 3

import java.util.Arrays;

public class arraySorter {
    public static void main(int[] a) {
        Arrays.sort(a);
        for (int i : a) {
            System.out.println(i);
        }
    }
}

int[] myNumbers = new int[] {5, 3, 4, 1, 2};
arraySorter.main(myNumbers);

Hack 4

// B

Hack 5

public class ForEachDemo
{
   public static void main(String[] args)
   {
     int[] highScores = { 10, 9, 8, 8};
     String[] names = {"Jamal", "Emily", "Destiny", "Mateo"};
     // for each loop with an int array
     for (int value : highScores)
     {
         System.out.println( value );
     }
     // for each loop with a String array
     for (String value : names)
     {
         System.out.println(value); // this time it's a name!
     }
   }
 }

Hack 6

// D

Hack 7

public class leftShifted {
    public static int[] main(int[] a) {
        int first = a[0];
        for (int i=1; i<a.length; i++) {
            a[i-1] = a[i];
        }
        a[a.length-1] = first;
        return a;
    }
}

int[] array = {7,9,4};
int[] array_out = leftShifted.main(array);

Arrays.toString(array_out)

[9, 4, 7]

Hack 8

public class findDuplicate {
    public static int main(int[] a, int b) {
        
        int d=0;

        for (int number : a) {
            if (number==b) {
                d++;
            }
        }
        return d;
    }
}

int[] array = {7,7,9,4};
findDuplicate.main(array, 7);

2

Hack 9

public class reverseString {
    public static char[] main(char[] s) {
        char[] reverse = new char[s.length];
        for (int i=s.length-1; i>=0; i--) {
            reverse[s.length-i-1] = s[i];
        }

        return reverse;
    }
}

String s = "hello";
char[] c = s.toCharArray();
char[] reverse = reverseString.main(c);

// Arrays.toString(reverse)
String reversed = new String(reverse);
System.out.println(reversed);

olleh

FRQ Part A

public void addMembers(String[] names, int gradYear) {
    for (String name : names) {
        MemberInfo member = new MemberInfo(name, gradYear, true);
        memberList.add(member);
    }
}