FloatingPointFun.java

package com.pholser;

import static java.lang.Float.*;
import static java.lang.Math.*;

public class FloatingPointFun {
    public static void main(String[] args) {
        showFloats();
    }

    private static void showFloats() {
        int lastExponent = Integer.MIN_VALUE;

        System.out.printf("Floats:\n====\n");
        for (float f = -Float.MAX_VALUE; f <= Float.MAX_VALUE; f = Math.nextUp(f)) {
            int exponent = getExponent(f);
            if (exponent != lastExponent) {
                if (f != -Float.MAX_VALUE)
                    show(Math.nextDown(f));
                show(f);
                lastExponent = exponent;
            }
        }

        show(Float.MAX_VALUE);
        show(Math.nextAfter(0F, Float.NEGATIVE_INFINITY));
        show(Math.nextAfter(0F, Float.POSITIVE_INFINITY));
        show(-0F);
        show(0F);
        show(Float.NaN);
        show(Float.NEGATIVE_INFINITY);
        show(Float.POSITIVE_INFINITY);
        System.out.println();
    }

    private static void show(float f) {
        System.out.printf("%.20E: exponent = %d, bits = %s, ulp = %.20E\n",
            f,
            getExponent(f),
            bits(f),
            ulp(f));
    }

    private static String bits(float f) {
        return String.format("%32s", Integer.toBinaryString(floatToIntBits(f))).replace(' ', '0');
    }
}