How to Reverse an Integer in Java

The challenge

Given a 32-bit signed integer, reverse digits of an integer.

Example 1:

Input: 123
Output: 321

Example 2:

Input: -123
Output: -321

Example 3:

Input: 120
Output: 21

Note:
Assume we are dealing with an environment which could only store integers within the 32-bit signed integer range: [−231,  231 − 1]. For the purpose of this problem, assume that your function returns 0 when the reversed integer overflows.

The solution

class Solution {
    // take in int, return int
    public int reverse(int x) {
        // set a Long variable to return
        // we make it a long incase we catch the edge case
        // of a larger size than int
        long out = 0;
        
        // loop while processing
        while(x!=0) {
            // multiple by 10 and add decimal place division
            out = out * 10 + x % 10;
            // move the decimal place by 1
            x /= 10;
        }
        
        // return 0 if edge case found
        if (Integer.MAX_VALUE<out || out<Integer.MIN_VALUE) return 0;
        // return the output and cast to an int
        return (int)out;
    }
}
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