RFR: 8262277: java.net.URLClassLoader.getResource throws undocumented IllegalArgumentException

[Craig Andrews]

On Sat, 20 Feb 2021 19:20:48 GMT, Craig Andrews <github.com+194713+candrews at openjdk.org> wrote:

> _NOTE_: I've reported this issue at https://bugreport.java.com/ (internal review ID : 9069151)
> 
> `java.net.URLClassLoader.getResource` can throw an undocumented `IllegalArgumentException`.
> 
> According to the javadoc for the `getResource` and `findResource` methods, neither should be throwing `IllegalArgumentException` - they should return null if the resource can't be resolved.
> 
> Quoting the javadoc for [`URLClassLoader.html#findResource`](https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/net/URLClassLoader.html#findResource(java.lang.String))
>> Returns:
>>     a URL for the resource, or null if the resource could not be found, or if the loader is closed.
> 
> And quoting the javadoc for [`ClassLoader.html#getResource`](https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/lang/ClassLoader.html#getResource(java.lang.String))
>> Returns:
>>     URL object for reading the resource; null if the resource could not be found, a URL could not be constructed to locate the resource, the resource is in a package that is not opened unconditionally, or access to the resource is denied by the security manager.
> 
> Neither mentions throwing `IllegalArgumentException` and both are clear that when URL can't be constructed, `null` should be returned.
> 
> Here's a stack trace:
> java.lang.IllegalArgumentException: name
>         at java.base/jdk.internal.loader.URLClassPath$Loader.findResource(URLClassPath.java:600)
>         at java.base/jdk.internal.loader.URLClassPath.findResource(URLClassPath.java:291)
>         at java.base/java.net.URLClassLoader$2.run(URLClassLoader.java:655)
>         at java.base/java.net.URLClassLoader$2.run(URLClassLoader.java:653)
>         at java.base/java.security.AccessController.doPrivileged(Native Method)
>         at java.base/java.net.URLClassLoader.findResource(URLClassLoader.java:652)
> 
> Looking at [`URLClassPath.findResource`](https://github.com/openjdk/jdk/blob/2b00367e1154feb2c05b84a11d62fb5750e46acf/src/java.base/share/classes/jdk/internal/loader/URLClassPath.java#L603)
>         URL findResource(final String name, boolean check) {
>             URL url;
>             try {
>                 url = new URL(base, ParseUtil.encodePath(name, false));
>             } catch (MalformedURLException e) {
>                 throw new IllegalArgumentException("name");
>             }
> 
> Instead of throwing `IllegalArgumentException`, that line should simply return `null`.
> 
> A similar issue exists at [`URLClassPath.getResource`](https://github.com/openjdk/jdk/blob/2b00367e1154feb2c05b84a11d62fb5750e46acf/src/java.base/share/classes/jdk/internal/loader/URLClassPath.java#L639)
>         URL findResource(final String name, boolean check) {
>             URL url;
>             try {
>                 url = new URL(base, ParseUtil.encodePath(name, false));
>             } catch (MalformedURLException e) {
>                 throw new IllegalArgumentException("name");
>             }
> 
> Instead of throwing `IllegalArgumentException`, that line should simply return `null`.

Submitted a bug report at https://bugreport.java.com/
Received internal review ID : 9069151

-------------

PR: https://git.openjdk.java.net/jdk/pull/2662