ADDITIONAL SYSTEM INFORMATION :
Windows 10
Java 20.0.1
Java 17.0.7
Java 11.0.18

A DESCRIPTION OF THE PROBLEM :
When reading a jar file with ZipInputStream, if the jar has been signed with jarsigner, ZipEntry.getSize() only reports a size of -1 for all files.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Read an unsigned jar entry-by-entry, invoking getSize() for each entry.
Sign the jar and repeat.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Both should report sizes for files that have sizes. For files added/modified by the signing process, the two may differ.
ACTUAL -
In the run against the unsigned jar, all files in the jar report a size.
In the run against the signed jar, no files in the jar report a size.

---------- BEGIN SOURCE ----------
package testpackage;

import java.io.IOException;
import java.net.URL;
import java.security.CodeSource;
import java.util.zip.ZipEntry;
import java.util.zip.ZipInputStream;

public class Launcher
{
        public static void main(String[] args)
        {
                CodeSource codeSource = Launcher.class.getProtectionDomain().getCodeSource();
                URL jarUrl = codeSource.getLocation();
                try( ZipInputStream zip = new ZipInputStream(jarUrl.openStream()))
                {
                        while(true)
                        {
                                ZipEntry e = zip.getNextEntry();
                                if (e == null)
                                        break;
                                System.out.print("Inspecting Zip Entry for " + e);
                                if(e.isDirectory()) System.out.println(" (Directory)");
                                System.out.println(" size/cSize: " + e.getSize() + "/" + e.getCompressedSize());
                        }
                } catch (IOException err)
                {
                        err.printStackTrace();
                }
        }
}

---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
Don't use sizes from signed jars (This implies that if you actually require the size, you can't sign the jar).

FREQUENCY : always