Problem of TreeSet/TreeMap

[urn1ce]

Problem of TreeSet/TreeMap

[joehni]

This is no bug, this is by design. A TreeSet/TreeMap may have an own Comparator and the Java API has no official way, to get them, therefore reflection is the only way. So, do as the exception says, run your application with run time option "--add-opens java.base/java.util=ALL-UNNAMED"

[urn1ce]

This is no bug, this is by design. A TreeSet/TreeMap may have an own Comparator and the Java API has no official way, to get them, therefore reflection is the only way. So, do as the exception says, run your application with run time option "--add-opens java.base/java.util=ALL-UNNAMED"

I known your meaning, but if i change like this (still not use "--add-opens java.base/java.util=ALL-UNNAMED")
public static void main(String[] args) {
var ts = new TreeSet();
//var al = new ArrayList();
//al.add("ABC");
//ts.add(al);
ts.add("");//String is Comparable
var xs = new XStream();
xs.allowTypesByWildcard(new String[]{"**"});
var str = xs.toXML(ts);
System.out.println(str);
var obj = xs.fromXML(str);//TreeMap has the same problem
System.out.println(obj);
}
The problem like this:
Exception in thread "main" java.lang.ExceptionInInitializerError
at com.thoughtworks.xstream.converters.collections.TreeSetConverter.unmarshal(TreeSetConverter.java:62)
at com.thoughtworks.xstream.core.TreeUnmarshaller.convert(TreeUnmarshaller.java:74)
at com.thoughtworks.xstream.core.AbstractReferenceUnmarshaller.convert(AbstractReferenceUnmarshaller.java:72)
at com.thoughtworks.xstream.core.TreeUnmarshaller.convertAnother(TreeUnmarshaller.java:68)
at com.thoughtworks.xstream.core.TreeUnmarshaller.convertAnother(TreeUnmarshaller.java:52)
at com.thoughtworks.xstream.core.TreeUnmarshaller.start(TreeUnmarshaller.java:136)
at com.thoughtworks.xstream.core.AbstractTreeMarshallingStrategy.unmarshal(AbstractTreeMarshallingStrategy.java:32)
at com.thoughtworks.xstream.XStream.unmarshal(XStream.java:1464)
at com.thoughtworks.xstream.XStream.unmarshal(XStream.java:1441)
at com.thoughtworks.xstream.XStream.fromXML(XStream.java:1321)
at com.thoughtworks.xstream.XStream.fromXML(XStream.java:1312)
at com.example.webenv174jar.XStreamTest.main(XStreamTest.java:26)
Caused by: java.lang.reflect.InaccessibleObjectException: Unable to make field private transient java.util.NavigableMap java.util.TreeSet.m accessible: module java.base does not "opens java.util" to unnamed module @11a9e7c8
at java.base/java.lang.reflect.AccessibleObject.checkCanSetAccessible(AccessibleObject.java:354)
at java.base/java.lang.reflect.AccessibleObject.checkCanSetAccessible(AccessibleObject.java:297)
at java.base/java.lang.reflect.Field.checkCanSetAccessible(Field.java:178)
at java.base/java.lang.reflect.Field.setAccessible(Field.java:172)
at com.thoughtworks.xstream.core.util.Fields.locate(Fields.java:40)
at com.thoughtworks.xstream.converters.collections.TreeSetConverter$Reflections.(TreeSetConverter.java:135)
This problem is also by design?

[joehni]

Yes, because how should XStream know, if a comparator has been set? There's just one way: Look into the private field.

[urn1ce]

Yes, because how should XStream know, if a comparator has been set? There's just one way: Look into the private field.

So even if not use comparator, also need "--add-opens java.base/java.util=ALL-UNNAMED", it maybe a bit redundant, if catch and handle exception may have a better experience., but i understand, thank you