Reverse int

gistfile1.txt

package reverse;

import org.apache.log4j.Logger;
import org.junit.Test;

import static org.hamcrest.MatcherAssert.assertThat;
import static org.hamcrest.core.Is.is;
import static org.hamcrest.core.IsEqual.equalTo;

/**
 * Author milesd on 27/05/2021.
 */
public class ReverseInt {
    @Test
    public void testReverseInt() {
        assertThat(Reverse.reverseInt(123), is(equalTo(321)));

        assertThat(Reverse.reverseInt(0), is(equalTo(0)));

        assertThat(Reverse.reverseInt(-123), is(equalTo(-321)));
    }
}

class Reverse {
    final static Logger logger = Logger.getLogger(Reverse.class);

    public static int reverseInt(int number) {
        boolean negative = false;

        if (number >= 0 && number < 10) {
            return number;
        } else if (number < 0) {
            negative = true;
            number = Math.abs(number);
        }

        int divParam = 1;
        final StringBuilder stringBuffer = new StringBuilder();

        while ((number / divParam) % 10 > 0) {
            int result = (number / divParam) % 10;
            logger.info(result);
            divParam = divParam * 10;
            stringBuffer.append(result);
        }

        if (negative) {
            return -Integer.parseInt(stringBuffer.toString());
        }

        return Integer.parseInt(stringBuffer.toString());
    }
}