CustomStack upgrades

My CustomStack now comes with several other new features. I can actually check if an Object exists in the Stack. Once the Object is found, a boolean true is returned. In addition to that, I've also added a method to retrieve an element with a given 0-based index number. I call it elementAt and it has a similar functionality of get. To the readers who are accustomed to the methods of a Stack, I have also added the method peek. Basically, it's a method to retrieve the element at the top of the Stack. The method search returns the 0-based index number of the first found element and -1 is returned if the element is not found. Here are the summary of methods of the newly improved CustomStack:
contains(Object input)
elementAt(int index)
peek()
search(Object input)
Below is the code snippet.

 public boolean contains(Object input){
  boolean found = false;
  if(empty()){
   throw new RuntimeException( "Stack is already empty. No elements to check." );
  }
  for(int i = 0; i<size(); i++) {
   if (stackElements[i].hashCode() == input.hashCode()) {
    found = true;
    break;
   }
  }
  return found;
 }

 public Object elementAt(int index){
  return get(index);
 }
 
 public Object peek(){
  return top();
 }
 
 public int search(Object input){
  int index = -1;
  if(empty()){
   throw new RuntimeException( "Stack is already empty. No elements to search." );
  }
  for(int i = 0; i<size(); i++) {
   if (stackElements[i].hashCode() == input.hashCode()) {
    index = i;
    break;
   }
  }
  return index;
 }
 

Click here to view the previous code of CustomStack.