Main.java Source code

Introduction

Here is the source code for Main.java

Source

//package com.java2s;
import java.text.DecimalFormat;

public class Main {
    private static final int canonicalFloatNaN = Float.floatToRawIntBits(Float.NaN);
    private static final int maxFloat = Float.floatToRawIntBits(Float.MAX_VALUE);
    private static final int piFloat = Float.floatToRawIntBits((float) Math.PI);
    private static final int eFloat = Float.floatToRawIntBits((float) Math.E);
    private static final DecimalFormat format = new DecimalFormat("0.####################E0");

    public static boolean isLikelyFloat(int value) {
        // Check for some common named float values
        // We don't check for Float.MIN_VALUE, which has an integer representation of 1
        if (value == canonicalFloatNaN || value == maxFloat || value == piFloat || value == eFloat) {
            return true;
        }

        // Check for some named integer values
        if (value == Integer.MAX_VALUE || value == Integer.MIN_VALUE) {
            return false;
        }

        // Check for likely resource id
        int packageId = value >> 24;
        int resourceType = value >> 16 & 0xff;
        int resourceId = value & 0xffff;
        if ((packageId == 0x7f || packageId == 1) && resourceType < 0x1f && resourceId < 0xfff) {
            return false;
        }

        // a non-canocical NaN is more likely to be an integer
        float floatValue = Float.intBitsToFloat(value);
        if (Float.isNaN(floatValue)) {
            return false;
        }

        // Otherwise, whichever has a shorter scientific notation representation is more likely.
        // Integer wins the tie
        String asInt = format.format(value);
        String asFloat = format.format(floatValue);

        // try to strip off any small imprecision near the end of the mantissa
        int decimalPoint = asFloat.indexOf('.');
        int exponent = asFloat.indexOf("E");
        int zeros = asFloat.indexOf("000");
        if (zeros > decimalPoint && zeros < exponent) {
            asFloat = asFloat.substring(0, zeros) + asFloat.substring(exponent);
        } else {
            int nines = asFloat.indexOf("999");
            if (nines > decimalPoint && nines < exponent) {
                asFloat = asFloat.substring(0, nines) + asFloat.substring(exponent);
            }
        }

        return asFloat.length() < asInt.length();
    }
}