Implement own ArrayList<> without using collections

Question

I am trying to implement my own ArrayList without using java collections for practice purposes. At this stage I want to implement two of main methods, add(E) and get(int) tp get the idea. My code is given below. However I encountered few issues:

1. The line "return (E) myData[index]" issues warning "Type safety: Unchecked cast from Object to E". How can I address that
2. The Java 7 implementation of ArrayList.add(T), returns a boolean. Under what circumstances the add() has to return false. Under what logic it return false and when returns true?
3. Where can I find the source code of java 7 implementation of ArrayList

PS. Kindly don't just answer question 3 and refer me to the sucrose code for one and two!

import java.util.Arrays;

public class MyArrayList<E>{
    private final int DEFAULT_SIZE=2;
    private Object[] myData = new Object[DEFAULT_SIZE];
    private int actSize=0;

    public boolean add(E data){
        if (actSize>=myData.length/2){
            increaseSize();
        }
        myData[actSize++] = data;
        return true;//when can it be false?
    }

    private void increaseSize()throws RuntimeException{
        myData = Arrays.copyOf(myData, myData.length*2);
    }

    public E get(int index) throws RuntimeException{
        if (index >= actSize){
            throw new IndexOutOfBoundsException(); 
        }
        return (E) myData[index];
    }

    public static void main(String[] args) {
        MyArrayList<String> arList = new MyArrayList<>();
        arList.add("Hello");
        arList.add("Bye bye!");
        System.out.println(arList.get(1));// prints Bye bye! which is correct

    }
}

Answer 1

The line "return (E) myData[index]" issues warning "Type safety: Unchecked cast from Object to E". How can I address that

Suppress the warning

@SuppressWarnings("unchecked")

The Java 7 implementation of ArrayList.add(T) returns a boolean. Under what circumstances the add() has to return false. Under what logic it return false and when returns true?

See the javadoc

Returns: true (as specified by Collection.add(E))

It always returns true.

Where can I find the source code of java 7 implementation of ArrayList

In your JDK installation's src.zip archive or find it online by simply searching

java ArrayList source code