NumberHelper.java

public class NumberHelper {

    static Class<? extends Number> getHighestNumberClass(final Number... numbers) {
        int bits = 8;
        boolean fp = false;
        for (final Number number : numbers) {
            int b;
            switch (number.getClass().getSimpleName()) {
                case "Short": b = 16; break;
                case "Integer": b = 32; break;
                case "Long": b = 64; break;
                case "Float": fp = true; b = 32; break;
                case "Double": fp = true; b = 64; break;
                default: b = 8; break;
            }
            bits = Math.max(bits, b);
        }
        if (fp) {
            if (bits <= 32) {
                return Float.class;
            } else if ( bits <= 64) {
                return Double.class;
            } else {
                return BigDecimal.class;
            }
        } else {
            if (bits <= 8) {
                return Byte.class;
            } else if ( bits <= 16) {
                return Short.class;
            } else if ( bits <= 32) {
                return Integer.class;
            } else if ( bits <= 64) {
                return Long.class;
            } else {
                return BigInteger.class;
            }
        }
    }
}