Java: Check if an element is present or not in a stack

Last update on May 09 2025 12:50:20 (UTC/GMT +8 hours)

8. Check if an element is present in the stack.

Write a Java program to implement a stack that checks if a given element is present or not in the stack.

Sample Solution:

Java Code:

import java.util.Scanner;
public class Stack {
  private int[] arr;
  private int top;

  // Constructor to initialize the stack
  public Stack(int size) {
    arr = new int[size];
    top = -1;
  }

  // Method to push an element onto the stack
  public void push(int num) {
    if (top == arr.length - 1) {
      System.out.println("Stack is full");
    } else {
      top++;
      arr[top] = num;
    }
  }

  // Method to pop an element from the stack
  public int pop() {
    if (top == -1) {
      System.out.println("Stack Underflow");
      return -1;
    } else {
      int poppedElement = arr[top];
      top--;
      return poppedElement;
    }
  }

  // Method to get the top element of the stack
  public int peek() {
    if (top == -1) {
      System.out.println("Stack is empty");
      return -1;
    } else {
      return arr[top];
    }
  }

  // Method to check if the stack is empty
  public boolean isEmpty() {
    return top == -1;
  }

  // Method to count elements
  public boolean contains(int element) {
    for (int i = 0; i <= top; i++) {
      if (arr[i] == element) {
        return true;
      }
    }
    return false;
  }

  public void display() {
    if (top == -1) {
      System.out.println("Stack is empty");
    } else {
      System.out.print("Stack elements: ");
      for (int i = top; i >= 0; i--) {
        System.out.print(arr[i] + " ");
      }
      System.out.println();
    }
  }

  public static void main(String[] args) {
    System.out.println("Initialize a stack:");
    Stack stack = new Stack(10);
    System.out.println("\nInput some elements on the stack:");
    stack.push(1);
    stack.push(3);
    stack.push(2);
    stack.push(0);
    stack.push(7);
    stack.push(5);
    stack.push(-1);
    stack.display();
    boolean result = stack.contains(0);
    System.out.println("\nIs 0 present in the stack? " + result);
    result = stack.contains(9);
    System.out.println("\nIs 9 present in the stack? " + result);
  }
}

Sample Output:

Initialize a stack:

Input some elements on the stack:
Stack elements: -1 5 7 0 2 3 1

Is 0 present in the stack? true

Is 9 present in the stack? false

Flowchart:

Flowchart: Java Exercises: Check if an element is present or not in a stack.

For more Practice: Solve these Related Problems:

Write a Java program to implement a method that checks for the presence of a specific element in a stack using recursion.
Write a Java program to search for an element in a stack using an iterative approach and return its position from the top.
Write a Java program to check if a stack contains a given element using Java streams by converting the stack to a stream.
Write a Java program to implement a custom contains() method for a stack that uses a loop and a flag variable.

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