It's not the best example for a solution, I'm just posting my solution:

import java.io.; import java.math.BigInteger; import java.util.;

public class DatatypeFitter {

public static void main(String[] args) throws IOException {
    BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(System.in));

    int q = Integer.parseInt(bufferedReader.readLine().trim());

    for (int i = 0; i < q; i++) {
        String strNum = bufferedReader.readLine().trim();

        BigInteger numBigDecimal = new BigInteger(strNum);

        int isBiggerThanLong = numBigDecimal.compareTo(BigInteger.valueOf(Long.MAX_VALUE));
        int isSmallerThanLong = numBigDecimal.compareTo(BigInteger.valueOf(Long.MIN_VALUE));

        if (isBiggerThanLong > 0 || isSmallerThanLong < 0) {
            System.out.println(strNum + " can't be fitted anywhere.");
        } else {
            System.out.println(strNum + " can be fitted in:");

            long num = numBigDecimal.longValue();


            if (num >= Byte.MIN_VALUE && num <= Byte.MAX_VALUE) {
                System.out.println("* byte");
            }
            if (num >= Short.MIN_VALUE && num <= Short.MAX_VALUE) {
                System.out.println("* short");
            }
            if (num >= Integer.MIN_VALUE && num <= Integer.MAX_VALUE) {
                System.out.println("* int");
            }
            System.out.println("* long");
        }
    }
}

}