Question

What is the best way to return an host object to JavaScript in Rhino? I have two classes like this:

public class Hosted extends org.mozilla.javascript.ScriptableObject {     private static final long serialVersionUID = 1;     public Hosted() {}     public void jsConstructor() {}      public String getClassName() {         return 'Hosted';     }      public Member jsGet_member() {         Member m = new Member();         m.defineFunctionProperties(new String[] { 'toString' }, m.getClass(), DONTENUM);         return m;     } }  public class Member extends org.mozilla.javascript.ScriptableObject {     private static final long serialVersionUID = 2;     public Member() {}     public void jsConstructor() {}      public String getClassName() {         return 'Member';     }      public String toString() {         return 'called toString()';     } } 

It works, in the sense that I can call the toString method, but the member object doesn’t behave as I would expect:

js> defineClass('Hosted'); js> defineClass('Member'); js> var h = new Hosted(); js> h.toString(); [object Hosted] js> h instanceof Hosted; true js> h.__proto__; [object Hosted] js>  js> var m = h.member; js> m.toString(); called toString() js> m instanceof Member; // Should be true false js> m.__proto__; // Should be [object Member] null 

If I call Object.prototype.toString though, it does say it’s a Member object:

js> Object.prototype.toString.call(m); [object Member] 

I’ve tried calling m.setPrototype and Context.javaToJS.

Answer 1

    public Scriptable jsGet_member() {         Scriptable scope = ScriptableObject.getTopLevelScope(this);         Member m = new Member();         m.setParentScope(scope);         // defineClass('Member') must have previously been called.         m.setPrototype(ScriptableObject.getClassPrototype(scope, 'Member'));         m.defineFunctionProperties(new String[] { 'toString' },                 m.getClass(), DONTENUM);         return m;     } 

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js> defineClass('Member') js> defineClass('Hosted') js> var h = new Hosted(); js> var m = h.member; js> m.toString(); called toString() js> m instanceof Member; true js> m.__proto__; [object Member] 

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Edit: The method can also be written:

    public Scriptable jsGet_member() {         Scriptable scope = ScriptableObject.getTopLevelScope(this);         Context cx = Context.getCurrentContext();         Member m = (Member)cx.newObject(scope, 'Member');         m.defineFunctionProperties(new String[] { 'toString' },                 m.getClass(), DONTENUM);         return m;     } 

which will call Member.jsConstructor; there may be other differences as well.