Answers to Self-Study Questions

for (int pos = 0; pos < 2*k; pos+=2) {
    words.add(pos, words.get(pos));
}

int pos = 0;
while (pos < words.size()) {
    String str = (String) words.get(pos);
    if (str.equals("hello")) {
        words.remove(pos);
    }
    else {
        pos++;
    }
}

public Object remove(int pos) {
    // check for bad pos
    if (pos < 0 || pos >= numItems) {
        throw new IndexOutOfBoundsException();
    }
 
    // get the item to be removed from pos
    Object ob = items[pos];

    // move items over to fill removed pos
    for (int k = pos; k < numItems-1; k++) {
        items[k] = items[k+1];
    }
 
    // decrease the number of items
    numItems--;
 
    // return the removed item
    return ob;
}
 
public Object get(int pos) {
    // check for bad pos
    if (pos < 0 || pos >= numItems) {
        throw new IndexOutOfBoundsException();
    }
 
    // return the item at pos
    return items[pos];
}