Consider detecting cycles when constructing JSONObjects

[cushon]

JSONObject.populateMap mentions that "the bean can not be recursive", and attempting to pass a recursive bean to JSONObject results in a StackOverflowError. The StackOverflowError can be hard to debug, because the stack trace is usually truncated before the frames that show where new JSONObject(bean) was called.

It might be worth detecting cycles when constructing JSONObjects to report a better error message for beans containing cycles.

import org.json.JSONObject;

class Json {

  public static void main(String[] args) {
    new JSONObject(new Foo());
  }

  public static class Foo {

    public Bar getBar() {
      return new Bar(this);
    }
  }

  public static class Bar {

    private final Foo foo;

    Bar(Foo foo) {
      this.foo = foo;
    }

    public Foo getFoo() {
      return foo;
    }
  }
}

Exception in thread "main" java.lang.StackOverflowError
	at java.base/java.lang.reflect.Method.getRoot(Method.java:68)
	at java.base/java.lang.reflect.Executable.declaredAnnotations(Executable.java:600)
	at java.base/java.lang.reflect.Executable.getAnnotation(Executable.java:572)
	at java.base/java.lang.reflect.Method.getAnnotation(Method.java:695)
	at java.base/java.lang.reflect.AnnotatedElement.isAnnotationPresent(AnnotatedElement.java:274)
	at java.base/java.lang.reflect.AccessibleObject.isAnnotationPresent(AccessibleObject.java:525)
	at org.json.JSONObject.getAnnotationDepth(JSONObject.java:1674)
	at org.json.JSONObject.getKeyNameFromMethod(JSONObject.java:1568)
	at org.json.JSONObject.populateMap(JSONObject.java:1538)
	at org.json.JSONObject.<init>(JSONObject.java:365)
	at org.json.JSONObject.wrap(JSONObject.java:2475)
	at org.json.JSONObject.populateMap(JSONObject.java:1543)
	at org.json.JSONObject.<init>(JSONObject.java:365)
	at org.json.JSONObject.wrap(JSONObject.java:2475)
	at org.json.JSONObject.populateMap(JSONObject.java:1543)
	at org.json.JSONObject.<init>(JSONObject.java:365)
	at org.json.JSONObject.wrap(JSONObject.java:2475)
	at org.json.JSONObject.populateMap(JSONObject.java:1543)
	at org.json.JSONObject.<init>(JSONObject.java:365)
	at org.json.JSONObject.wrap(JSONObject.java:2475)
	at org.json.JSONObject.populateMap(JSONObject.java:1543)
	at org.json.JSONObject.<init>(JSONObject.java:365)
	at org.json.JSONObject.wrap(JSONObject.java:2475)
	at org.json.JSONObject.populateMap(JSONObject.java:1543)
	at org.json.JSONObject.<init>(JSONObject.java:365)
	at org.json.JSONObject.wrap(JSONObject.java:2475)
	at org.json.JSONObject.populateMap(JSONObject.java:1543)
	at org.json.JSONObject.<init>(JSONObject.java:365)
	at org.json.JSONObject.wrap(JSONObject.java:2475)
	at org.json.JSONObject.populateMap(JSONObject.java:1543)

[stleary]

No objections if anyone would like to try to implement this.

[guptnis]

Hi @stleary I would like to try to implement this.

[stleary]

Sure @guptnis, please go ahead

[stleary]

See #633

[gdmanandamohon]

Hi, @stleary I was just wondering what is the depth fo the bean? if it's multilevel parent-child relationship or just single level.
I am thinking of solving this problem with DFS traversal therefore wondering how is the depth level.

To clarify more, this is providing the 1st level functions of the class
Method[] methods = includeSuperClass ? klass.getMethods() : klass.getDeclaredMethods();

do we have to consider the child level of the methods? I am asking because through the populateMap function I assume you have just arranged the bean in the first level. Could you please clarify? Thanks!

[stleary]

@gdmanandamohon another developer is working on this issue, let's give him a chance to finish his work.

[stleary]

Closing this issue since a solution has been accepted. See #645