6.1 Array Creation and Access

Used to store one data type
Fixed size and canno tbe chnaged
Import array through: import java.util.Arrays;
Making Arrays: using constructors or using pre-initialized arrays

6.2 Traversing Arrays

For loop or while loop
Bound errors: appears when using loops to access array elements
When there's not enough items to reach an index

6.3 Enhanced For Loops

Traverse through most data structures
Elements in array need to have something done to
Mutator methods: set the value on instance variables

6.4 Developing Algorithms using Arrays

Minimum and maximum of a list of elements
Compute sum, average, or mode
If you want to find if an array has a specific property
Can determine duplicates
.length can be used to find the length of an array
array [i] to find the value
change value: array [i] = new element

Hack 1

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

Hack 2

The answer is 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

The answer is 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

The answer is 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);
    }
}