Converting Byte to Megabyte in Java getting zero

Question

I was having some problem when trying to convert bytes to megabyte in Java. What I have tried to do is:

        long inodeSpace = 100000;
        long MEGABYTE = 1024L * 1024L;
        long inodeSpaceInMb = inodeSpace / MEGABYTE;
        System.out.println("INODE SPACE " + inodeSpace);
        System.out.println("INODE MB " + inodeSpaceInMb);

I tried to print out the inodeSpaceMb, however, I am getting 0. Any ideas why is it so?

100000 (inodeSpace)/ 1048576(MEGABYTE ) = 0. Seem it's a correct to me — Dang Nguyen, Nov 01 '18 at 07:17
You are doing integer division, any result less than zero will become zero. Use double instead. — Ricky Mo, Nov 01 '18 at 07:17
@RickyMo That's not entirely true. Results can be less than zero, but any value will have its mantissa truncated, i.e. `0.73351` becomes `0`. — MC Emperor, Nov 01 '18 at 07:22

score 2 · Accepted Answer · answered Nov 01 '18 at 07:20

2

Cast one of the two into a double and store the result in a double. Like:

double inodeSpaceInMb = (double) inodeSpace / MEGABYTE;

answered Nov 01 '18 at 07:20

MrMister

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I see I see thanks so much! – dummygg Nov 01 '18 at 07:33

score 0 · Answer 2 · answered Nov 01 '18 at 08:12

If you also want some precision to a specific decimal place when you do the conversion then you can do this:

 public double bytesToMegabytes(long byteValue, int precision) {
     if (precision < 0) {
         throw new IllegalArgumentException("Precision can not be less than 0!");
     }
     double mbValue = byteValue * 0.000001;
     BigDecimal bigDec = new BigDecimal(mbValue);
     bigDec = bigDec.setScale(precision, RoundingMode.HALF_UP);
     return bigDec.doubleValue();
}

Converting Byte to Megabyte in Java getting zero

2 Answers2