A ZipEntry that was being retrieved through ZipInputStream.getNextEntry()
returns -1 when getCompressedSize() and getSize() are being asked.
I have tried this by creating an archive of an directory using jar -cvMf ...

Testcase:

import java.io.*;
import java.util.*;
import java.util.zip.*;

public class test extends Object
{
	static public void main(String args[]) throws Exception {
		ZipInputStream	inzip = null;
		ZipEntry	entry = null;

		inzip = new ZipInputStream(new FileInputStream("somearchive"));
		while (true) {
			entry = inzip.getNextEntry();
			if (entry.getName().equals("somefile")) {
				System.out.println(" Name: " +
					entry.getName());
				System.out.println("CSize: " +
					entry.getCompressedSize());
				System.out.println("USize: " +
					entry.getSize());
				break;
			}
		}
	}
}