Object cannot be converted to int y = st.peek(); object cannot be converted to int x = st.peek(); can somebody help me with this

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1.00/5 (1 vote)

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import java.util.*;
public class Reverse_A_Stack_Using_Recursion

{
    static void insert_at_bottom(Stack st, int x)
    {
     int y;
     if(st.size() == 0)
     {
         st.push(x);
     }else
     {
       y = st.peek();
       st.pop();
       insert_at_bottom(st,x);
       st.push(y);
     }   
    }
    static void reverse(Stack st)
    {
     int x;
     if(st.size() > 0)
     {
         x = st.peek();
         st.pop();
         reverse(st);
         insert_at_bottom(st,x);
     }   
    }
   public static void main(String []args)
   {
        Stack<Integer> st = new Stack<Integer>();
        st.push(4);
        st.push(3);
        st.push(2);
        st.push(1);
        reverse(st);
       System.out.println(st);  
        
    }
    
}

What I have tried:

Stack i have is of Integer then why while peeking an object is peeked

Posted 5-Jan-22 20:10pm

Mohit lakhwani

Updated 5-Jan-22 20:51pm

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2 solutions

Solution 2

A shorter way of resolving the issue is to force type casting from object to int.

x = Convert.ToInt32(st.peek());

You need to convert object to int on all peek() calls.

But more elegant approach would be to use the way that @OG has suggested.

Posted 5-Jan-22 20:51pm

_Asif_

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OriginalGriff · Accepted Answer · 2022-01-05T20:25:00

Because when you declare the method, you say this:

static void insert_at_bottom(Stack st, int x)

Which means that st can contain any value: an Object, and you can;t automatically convert an Object to any other type.

Instead, tell the system what your stack contains, and it'll understand what you are doing:

static void insert_at_bottom(Stack<Integer> st, int x)

You will need to do the same to your reverse method as well.