Java dsa-Stack

Stack/StackLL.java

@@ -0,0 +1,109 @@
+package Java_DSA.Stack;
+
+import java.util.EmptyStackException;
+import java.util.Scanner;
+
+public class StackLL {
+    private Node top;
+
+    private class Node{
+        int data;
+        Node next;
+        public Node(int data){
+            this.data = data;
+            this.next = null;
+        }
+    }
+    public boolean isEmpty(){
+        return top == null;
+    }
+
+    public void display(){
+        if(isEmpty()){
+            System.out.println("Stack is Empty.");
+            return;
+        }
+        Node ptr = top;
+        while(ptr != null){
+            System.out.println(ptr.data);
+            ptr = ptr.next;
+        }
+        System.out.println();
+    }
+
+    public void push(int data){
+        Node temp = new Node(data);
+        if(isEmpty()){
+            top = temp;
+            return;
+        }
+        temp.next = top;
+        top = temp;
+    }
+
+    public int pop(){
+        if (isEmpty()){
+            System.out.println("Stack is Empty,No element to pop.");
+            throw new EmptyStackException();
+        }
+        int data = top.data;
+        top = top.next;
+        return data;
+    }
+
+    public int peek(){
+        if(isEmpty()){
+            System.out.println("Stack is Empty.");
+            throw new EmptyStackException();
+        }
+        return top.data;
+    }
+
+    public int calSize(){
+        int size = 0;
+        if(isEmpty()){
+            return 0;
+        }
+        Node ptr = top;
+        while(ptr != null){
+            size++;
+            ptr = ptr.next;
+        }
+        return size;
+    }
+    public static void main(String[] args) {
+        Scanner sc = new Scanner(System.in);
+        StackLL stack = new StackLL();
+        boolean flag = true;
+        System.out.println("1)Push.\n2)Pop.\n3)Peek.\n4)Display.\n5)Calculate size.\n6)Exit.");
+        while(flag){
+            System.out.println("Enter your choice : ");
+            int choice = sc.nextInt();
+            switch (choice){
+                case 1->{
+                    System.out.println("Enter data to push : ");
+                    int value = sc.nextInt();
+                    stack.push(value);
+                }
+                case 2->{
+                    System.out.println("Popped element is : "+stack.pop());
+                }
+                case 3->{
+                    System.out.println("Peek of stack is : "+stack.peek());
+                }
+                case 4->{
+                    stack.display();
+                }
+                case 5->{
+                    System.out.println("Size of the stack is : "+stack.calSize());
+                }
+                case 6->{
+                    flag = false;
+                }
+                default -> {
+                    System.out.println("Invalid choice..!!");
+                }
+            }
+        }
+    }
+}