Binding a Java Integer to JavaScriptEngine doesn't work
- by rplantiko
To see how binding Java objects to symbols in a dynamic language works, I wrote the following spike test, binding a java.lang.Integer to the symbol i to be changed in JavaScript:
@Test
public void bindToLocalVariable() throws ScriptException {
javax.script.ScriptEngineManager sem
= new javax.script.ScriptEngineManager();
javax.script.ScriptEngine engine
= sem.getEngineByName("JavaScript");
Integer i = new Integer(17);
engine.put( "i", i );
engine.eval( "i++;" ); // Now execute JavaScript
assertEquals( 18, i.intValue() );
}
Unfortunately, I get a failure.
java.lang.AssertionError: expected:<18> but was:<17>
JavaScript knows the symbol i (otherwise it would have thrown a ScriptException which is not the case), but the increment operation i++ is not performed on the original Integer object.
Any explanations?
