Question: What is the issue with peek2 package stackdriver; public interface StackInterface { public boolean isEmpty(); public void push(T newEntry); public T pop(); public T peek();
What is the issue with peek2
package stackdriver;
public interface StackInterface
public boolean isEmpty();
public void push(T newEntry);
public T pop();
public T peek();
public T peek2();
public void clear();
}
package driverstack;
import java.util.Stack;
public class DriveStack
public static void main(String[] args) {
Stack
System.out.println(stack.isEmpty());
stack.push("Star Wars");
System.out.println(stack.isEmpty());
stack.push("Black Panther");
System.out.println("ttt" +stack.peek2());
}
}
package stackdriver;
import java.util.EmptyStackException;
public class LinkedListStack
private Node topNode;
public boolean isEmpty() {
return topNode == null;
}
public void push(T newEntry) {
Node newNode = new Node(newEntry, topNode);
topNode = newNode;
}
public T pop() {
T top = peek();
topNode = topNode.forward;
return top;
}
public T peek() {
if (isEmpty()) {
throw new EmptyStackException();
}else {
return topNode.getInfo();
}
}
public T peek2() {
if (isEmpty()) {
return null;
}else {
T top = null;
if(topNode.forward == null) {
return null;
} else {
top = topNode.forward.getInfo();
return top;
}
}
}
public void clear() {
topNode = null;
}
private class Node {
private T info;
private Node forward;
public Node(T newInfo) {
info = newInfo;
forward = null;
}
public Node(T infoStack, Node connectStack) {
info = infoStack;
forward = connectStack;
}
public void setInfo(T newInfo) {
info = newInfo;
}
public T getInfo() {
return info;
}
public Node getNextNode() {
return forward;
}
public void setNextInfo(Node forwardNode) {
forward = forwardNode;
}
}
}
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