java zipentry getsize returns -1

Question

Java zipEntry.getSize() returns the size of the actual file and some times it returns -1 (though the file size is greater than 0).

Java API document says "Returns the uncompressed size of the entry data, or -1 if not known."

Not sure on what situation it will return -1 i.e. on what situation it will be unknown?

FWIW if you call `getSize` after reading the stream for that ZipEntry, then it will return the right size. Weird. — rogerdpack, Mar 02 '18 at 17:55

score 9 · Answer 1 · answered Oct 25 '16 at 20:37

Surprisely using ZipFile instead of ZipInputStream for getting the entries makes getSize and getCompressedSize to return the right values.

     ZipFile zipfile = new ZipFile("myFile.zip"); 
     java.util.Enumeration zipEnum = zipfile.entries();
     while (zipEnum.hasMoreElements ()) 
     { 
        ZipEntry entry = (ZipEntry) zipEnum.nextElement(); 
        if (! entry.isDirectory ())
        {
            // entry.getName()
            // entry.getSize ()
            // entry.getCompressedSize ()
         }
     }

trick found at http://vimalathithen.blogspot.de/2006/06/using-zipentrygetsize.html

score 1 · Accepted Answer · answered Mar 16 '16 at 19:41

1

you'll get a return of -1 if that is what is in the ZipFile entry table. This is quite simply just an aspect of the definition of the zip file format.

answered Mar 16 '16 at 19:41

ControlAltDel

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I get -1 even after writing the size to the zip table with the size function. – Johann May 30 '21 at 11:42

Muhammed naseef Koppilakkal · Answer 3 · 2022-12-11T11:13:24.330

This code will return the correct size of zipEntry:

ZipInputStream( BufferedInputStream( cr.openInputStream(zipUri) ) ).use { srcZipStream ->
        var zipEntry: ZipEntry?
        while (srcZipStream.nextEntry.also { zipEntry = it} != null) {
            srcZipStream.closeEntry()
            allZipEntryList.add(zipEntry!!.name)
            Log.e("wkExtract",zipEntry!!.name+" size= "+zipEntry!!.size+" compressed size= "+zipEntry!!.compressedSize)
        }
}

java zipentry getsize returns -1

3 Answers3