jar-classpath-bug

Demonstrates a problem with % character in Class-Path attribute of MANIFEST.MF.

It appears that Java doesn't support file paths that contain % in Class-Path attribute of MANIFEST.MF. I reproduced this problem on WIndows and on Linux, on different versions of java up to 11.02.

Set up

1. Class Library is in lib.jar which is copied into folders bin/foo%3a and bin/foo_3a (for comparison)
2. Class Main uses Library and has a main method. It's class file is in bin
3. bin/bad-classpath.jar is a classpath jar that refers to foo%3a/lib.jar in its MANIFEST.MF:

   Class-Path: foo%3a/lib.jar
   

4. bin/good-classpath.jar is a classpath jar that refers to foo_3a/lib.jar in its MANIFEST.MF:

   Class-Path: foo_3a/lib.jar
   

5. bin/encoded-classpath.jar is a classpath jar that refers to URL-encoded version of foo%3a/lib.jar in its MANIFEST.MF:

   Class-Path: foo%253a/lib.jar
   

Scenarios

Without classpath jar:

Run java -cp bin/foo%3a/lib.jar:bin Main. This completes successfully and prints

Loaded library: Library@2c8d66b2

With good-classpath.jar:

Run java -cp bin/good-classpath.jar:bin Main. This also works fine:

Loaded library: Library@35bbe5e8

With bad-classpath.jar:

Run java -cp bin/bad-classpath.jar:bin Main. This time java can't find the Library class in foo%3a/lib.jar

Exception in thread "main" java.lang.NoClassDefFoundError: Library
        at Main.main(Main.java:3)
Caused by: java.lang.ClassNotFoundException: Library
        at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:582)
        at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:190)
        at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:499)
        ... 1 more

With encoded-classpath.jar:

Run java -cp bin/encoded-classpath.jar:bin Main. This also works fine:

Loaded library: Library@6b71769e