Reverse a string using Stack Java

PROGRAM TO REVERSE A STRING USING STACK



import java.util.*;
  
//stack
class Stack
{
    int size;
    int top;
    char[] a; 
  
    //function to check if stack is empty
    boolean isEmpty()
    {
        return (top < 0);
    }
      
    Stack(int n)
    {
        top = -1;
        size = n;
        a = new char[size];
    }
  
    //function to push element in Stack
    boolean push(char x)
    {
        if (top >= size)
        {
        System.out.println("Stack Overflow");
        return false;
        }
        else
        {
            a[++top] = x;
            return true;
        }
    }
  
    //function to pop element from stack
    char pop()
    {
        if (top < 0)
        {
        System.out.println("Stack Underflow");
        return 0;
        }
        else
        {
            char x = a[top--];
            return x;
        }
    }
}
  
  
// Driver code
class Main
{
    //function to reverse the string
    public static void reverse(StringBuffer str)
    {
        // Create a stack of capacity 
        // equal to length of string
        int n = str.length();
        Stack obj = new Stack(n);
          
        // Push all characters of string 
        // to stack
        int i;
        for (i = 0; i < n; i++)
        obj.push(str.charAt(i));
      
        // Pop all characters of string 
        // and put them back to str
        for (i = 0; i < n; i++)
        { 
            char ch = obj.pop();
            str.setCharAt(i,ch);
        }
    } 
      
    //driver function
    public static void main(String args[])
    {
        //create a new string
        StringBuffer s= new StringBuffer("GeeksQuiz");
          
        //call reverse method
        reverse(s);
          
        //print the reversed string
        System.out.println("Reversed string is " + s);
    }
}


OUTPUT:
Reversed string is ziuQskeeG

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