Question

Extra Credit: The following Java code implements a Stack using an ArrayList. Write a method "peek", that returns the String at the top of the Stack without removing the String from the Stack. (the pop() method removes the element at the top of the stack. The peek() method does not modify the Stack.) Write 'peek' using only the methods that currently exist in the Stack class. ? import java.util.* public class Stack { private ArrayList<String> elements = new ArrayList<>(); public String pop() { ? if (elements.isEmpty()) { return null; } String top = elements.get(elements.size() - 1); elements.remove(elements.size() - 1); return top; } public void push(String element) { ? elements.add(element); } public boolean isEmpty() { ? return elements.isEmpty(); } }

          Extra Credit: The following Java code implements a Stack using an ArrayList.
Write a method "peek", that returns the String at the top of the Stack without
removing the String from the Stack. (the pop() method removes the element at the
top of the stack. The peek() method does not modify the Stack.)
Write 'peek' using only the methods that currently exist in the Stack class.
?
import java.util.* 
public class Stack {
private ArrayList<String> elements = new ArrayList<>();
public String pop() {
?
if (elements.isEmpty()) {
return null;
}
String top = elements.get(elements.size() - 1);
elements.remove(elements.size() - 1);
return top;
}
public void push(String element) {
?
elements.add(element);
}
public boolean isEmpty() {
?
return elements.isEmpty();
}
}

Extra Credit: The following Java code implements a Stack using an ArrayList.
Write a method "peek", that returns the String at the top of the Stack without
removing the String from the Stack. (the pop() method removes the element at the
top of the stack. The peek() method does not modify the Stack.)
Write 'peek' using only the methods that currently exist in the Stack class.
?
import java.util.*
public class Stack
private ArrayList<String> elements = new ArrayList<>();
public String pop()
?
if (elements.isEmpty())
return null;

String top = elements.get(elements.size() - 1);
elements.remove(elements.size() - 1);
return top;

public void push(String element)
?
elements.add(element);

public boolean isEmpty()
?
return elements.isEmpty();

Added by Scott F.

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