Calling ClassInfo.getResource().open() after scanResult is closed results in NPE #885
Description
Calling ClassInfo.getResource().open() after the ScanResult is closed results in a ClassGraph internal NullPointerException.
Reproducer:
package example;
import java.io.IOException;
import io.github.classgraph.*;
class ClassGraphTest {
@org.junit.jupiter.api.Test
void testClassGraph() throws IOException {
final var className = ClassGraphTest.class.getName();
final ClassInfo classInfo;
try (ScanResult scanResult = new ClassGraph() //
.enableAllInfo() //
.acceptClasses(className) //
.scan()) {
classInfo = scanResult.getClassInfo(className);
}
try (var res = classInfo.getResource();
var is = res.open()) { // <--- NPE thrown here
// do interesting stuff
}
}
}Exception:
java.lang.NullPointerException: Cannot invoke "java.util.Set.add(Object)" because "this.openSlices" is null
at nonapi.io.github.classgraph.fastzipfilereader.NestedJarHandler.markSliceAsOpen(NestedJarHandler.java:517)
at nonapi.io.github.classgraph.fileslice.PathSlice.<init>(PathSlice.java:152)
at io.github.classgraph.ClasspathElementDir$2.openAndCreateSlice(ClasspathElementDir.java:295)
at io.github.classgraph.ClasspathElementDir$2.open(ClasspathElementDir.java:249)
at example.ClassGraphTest.testClassGraph(ClassGraphTest.java:25)
at java.base/java.lang.reflect.Method.invoke(Method.java:568)
at java.base/java.util.ArrayList.forEach(ArrayList.java:1511)
at java.base/java.util.ArrayList.forEach(ArrayList.java:1511)Interestingly the same works for JDK built-ins like "java.lang.Integer" and does not throw an NPE
Tested with OpenJDK 17 and classgraph 4.8.176