Merge pull request #82 from zomsik/main

Implementation of a Stack class in own way

Author: Ritikraja07

Stack.java

@@ -0,0 +1,134 @@
+
+//Importing Scanner class for input
+import java.util.Scanner;
+import java.util.InputMismatchException;
+
+// Stack class
+class Stack {
+    private int top;
+    private int maxSize;
+    private int stack[];
+
+    // Constructor for Stack class intialize stack with given maximum size
+    public Stack(int maxSize) {
+        this.maxSize = maxSize;
+        this.stack = new int[maxSize];
+        this.top = -1; // stack is empty
+    }
+
+    // adding element to stack
+    public void push(int element) {
+        if (top == maxSize - 1) { // to check stack is full
+            System.out.println("-1");
+            return;
+        }
+        stack[++top] = element; // increasing the top and adding element
+    }
+
+    // removing element from stack
+    public void pop() {
+        if (top == -1) { // to check stack is empty
+            System.out.println("-1");
+            return;
+        }
+        top--; // decrement top and get element at top of stack
+    }
+
+    // to get top of stack
+    public int peek() {
+        if (top == -1) { // to check stack is empty
+            return -1;
+        }
+        return stack[top]; // get top element of stack
+    }
+
+    // method to check empty stack
+    public boolean isEmpty() {
+        return top == -1;
+    }
+
+    // method to check stack is Full
+    public boolean isFull() {
+        return top == maxSize - 1;
+    }
+
+    // to display the stack
+    public void display() {
+        if (top == -1) { // to check stack is empty
+            return;
+        }
+        for (int index = top; index >= 0; index--) {
+            System.out.print(stack[index] + " ");
+        }
+    }
+
+    public static void main(String[] args) {
+        try (Scanner input = new Scanner(System.in)) {
+            System.out.println("Enter size of stack you want: ");
+            int maxSize = input.nextInt(); // user input for max size
+            Stack stack = new Stack(maxSize);
+            int choice;
+            do {
+                System.out.println("1. Push");
+                System.out.println("2. Pop");
+                System.out.println("3. Peek");
+                System.out.println("4. Is empty");
+                System.out.println("5. Display");
+                System.out.println("6. Exit");
+                System.out.println("Enter your choice: ");
+                choice = input.nextInt(); // getting user's choice
+                switch (choice) {
+                    case 1:
+                        System.out.println("Enter element to push: ");
+                        int element = input.nextInt();
+                        if (stack.isFull()) {
+                            System.out.println("stack is full");
+                            break;
+                        }
+                        stack.push(element);
+                        break;
+                    case 2:
+                        if (stack.isEmpty()) {
+                            System.out.println("Stack is empty");
+                            break;
+                        }
+                        int top = stack.peek();
+                        stack.pop();
+                        System.out.println("Deleted element is " + top);
+                        break;
+                    case 3:
+                        if (stack.isEmpty()) {
+                            System.out.println("Stack is empty");
+                            break;
+                        }
+                        System.out.println("Top element is " + stack.peek());
+                        break;
+                    case 4:
+                        if (stack.isEmpty()) {
+                            System.out.println("Stack is empty");
+                        } else {
+                            System.out.println("Stack is not empty");
+                        }
+                        break;
+                    case 5:
+                        if (stack.isEmpty()) {
+                            System.out.println("stack is empty");
+                            break;
+                        }
+                        stack.display();
+                        System.out.println();
+                        break;
+                    case 6:
+                        System.out.println("Exit done");
+                        break;
+                    default:
+                        System.out.println("Invalid choice");
+                }
+            } while (choice != 6);
+        } catch (InputMismatchException exception) {
+            System.out.println(exception);
+        } catch (Exception exception) {
+            System.out.println(exception);
+        }
+    }
+}