String ArrayList. Targeted at AP Computer Science Students. Used with https://www.youtube.com/watch?v=JcTA3grnERo

ArrayListString.java

public class ArrayListString{
    
    private String[] arr;
    private int capacity;
    private int size;
    
    public ArrayListString() {
        arr = new String[10];
        capacity = 10;
        size = 0;
    }

    public boolean add(String str)
    {
        if (capacity <= size) {
            resize(capacity * 2);
            capacity = capacity * 2;
        }
        arr[size] = str;
        size++;
        return true;
    }

    private void resize(int newCapacity)
    {
        //Create a new String array with newCapacity elements
        String[] newArr = new String[newCapacity];
        //Copy all of the old elements into this new array
        for(int counter = 0;counter<capacity;counter++) {
            newArr[counter] = arr[counter];
        }
        //Change field (arr) to reference new array
        arr = newArr;
    }

    public int size() {
        return size;
    }
    
    public void add(int index, String str) {
        //check if capacity is good.  If not, expand
        if (capacity <= size) {
            resize(capacity * 2);
            capacity = capacity * 2;
        }
        //move items at index, index+1...end of list to the right.
        for(int counter = size-1;counter>=index;counter--) {
            arr[counter+1] = arr[counter];
        }
        //Add our item
        arr[index] = str;
        size++;
    }
    
    public String get(int index) {
        if (index >= 0 && index<size)  {
            return arr[index];
        }
        System.out.println("Out of range");
        return null;
    }
    
    public void set(int index, String str) {
        if (index >= 0 && index < size)  {
            arr[index] = str;
            return;
        }
        System.out.println("Out of range");
    }
    
    public String remove(int index) {
        //Make a local that holds onto the element we remove
        String temp = arr[index];
        //Move all elements index+1, index+2 ... one index to the left
        for(int counter = index;counter<size-1;counter++) {
            arr[counter] = arr[counter+1];
        }
        size--;
        //return removedElement
        return temp;
    }
}

Runner.java

public class Runner
{
    public static void main(String[] args) {
        ArrayListString list = new ArrayListString();
		boolean didAdd = list.add("Hello,");
		didAdd = didAdd && list.add("World!");
		System.out.println("Both items added: "+didAdd);
		System.out.println("Should be 2 : "+list.size());
		
		for(int i = 0;i<20;i++) {
			list.add("!");
		}
		System.out.println("Should be 22 : "+list.size());
		
		//add to middle
		list.add(1, "Middle");
		System.out.println("Should be 23 : "+list.size());
		
		
		System.out.println("SHould be World! "+list.get(2));
		list.set(0, "Goodbye");
		System.out.println("Should be Goodbye "+list.get(0));
		
		String removedValue = list.remove(1);
		System.out.println("Removed "+removedValue);
		//System.out.println(list);
    }
}