Java: Verify all stack elements satisfy a condition

Java Stack: Exercise-26 with Solution

Write a Java program that implements a stack and checks if all elements of the stack satisfy a condition.

Sample Solution:

Java Code:

import java.util.*;
import java.util.function.Predicate;
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 get the size of the stack
  public int getSize() {
    return top + 1;
  }

  public boolean allMatch(Predicate < Integer > predicate) {
    for (int i = top; i >= 0; i--) {
      if (!predicate.test(arr[i])) {
        return false;
      }
    }
    return true;
  }

  // Method to display the elements of the stack
  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) {
    Stack stack = new Stack(5);
    stack.push(2);
    stack.push(4);
    stack.push(6);
    stack.push(8);
    stack.display();
    boolean all_Even = stack.allMatch(x -> x % 2 == 0);
    System.out.println("\nCheck if all elements of this stack are even! " + all_Even);
    boolean all_odd = stack.allMatch(x -> x % 2 != 0);
    System.out.println("Check if all elements of this stack are odd! " + all_odd);
  }
}

Sample Output:

Stack elements: 8 6 4 2

Check if all elements of this stack are even! true
Check if all elements of this stack are odd! false

Flowchart:

Live Demo:

Java Code Editor:

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Java Stack Exercises Next: Verify at least one element satisfy a condition.