JAVA how to detect a binary file contains zero values?

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Hi there, i want to make a java code that know a binary file have zero value
file value like this will give boolean false:

00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

And file value like this will give boolean true:

30 09 02 20 09 02 F0 08 02 D4 08 02 A4 08 06 60 08 01 B8 15 01 F4 15 01 F4 15 01 2C 15 01 64 14 01 64 14 01 98 13 01 34 13 01 D0 12 01 6C 12 01 A4 11 01 DC 10 01 14 10 01 80 0E 01 B8 0D 01 54 0D 01 F0 0C 01 8C 0C 01 C0 0B 01 F8 0A 01 30 0A

What I have tried:

Im using java.io.File

variable

File landMapH32File

condition but not working:

if (landMapH32File.exists() && landMapH32File.length() > 0) {}

this condition will return true even if a file contains zero values. Its must return false.

Posted 20-Jul-17 2:31am

EADever

Updated 20-Jul-17 3:12am

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2 solutions

Solution 2

Thanks @Richard MacCutchan for giving sugguestion:

this code work for me:

public static void main(String[] args) throws IOException {

		File file = new File("c:\\arena_l_lobby_land_map.h32");
        FileInputStream in = null;

        try {
            in = new FileInputStream(file);
            int c;
            boolean d = false;

            while ((c = in.read()) != -1) {
            	if (c > 0) {
            		d = true;
            	}
            }
            System.out.println(d);
        } finally {
            if (in != null) {
                in.close();
            }
        }
    }

Posted 20-Jul-17 3:12am

EADever

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Richard MacCutchan · Accepted Answer · 2017-07-20T02:40:00

Solution 1

Of course it will return true. You are only testing whether the file exists and contains anything. You need to read the contents and look for non-zero bytes.

Posted 20-Jul-17 2:40am

Richard MacCutchan

Comments

EADever 20-Jul-17 8:42am

Can you give a sample code to read contents and look to non-zero bytes?

Richard MacCutchan 20-Jul-17 8:46am

See Byte Streams (The Java™ Tutorials, Essential Classes, Basic I/O)[^]

EADever 20-Jul-17 8:47am

public static void main(String[] args) throws IOException {
FileInputStream fis = new FileInputStream(new File("c:\\arena_l_lobby_land_map.h32"));
int iByteCount = fis.read();
if (iByteCount == -1)
System.out.println("stream not empty");
else
System.out.println("stream is empty");
}

this is correct?

Richard MacCutchan 20-Jul-17 8:51am

No, you need to read each byte and look for the first one that contains a value greater than zero.