How to use stringbuilder in transform

[rutledj]

I was trying to use the stringbuilder but not having much luck. How do I add strings to the stringbuilder and then read them out?

Tried this:

var strBuilder = new java.lang.StringBuilder();
   strBuilder.append('Hello");
   logger.info(strBuilder);

but get and error

The choice of Java method java.lang.StringBuilder.append matching JavaScript argument types (org.mozilla.javascript.Undefined) is ambiguous; candidate methods are: 
class java.lang.AbstractStringBuilder append(java.lang.String)
class java.lang.AbstractStringBuilder append(java.lang.Object)

[jonbartels]

Try this:

var strBuilder = new java.lang.StringBuilder();
   strBuilder.append('Hello");
   logger.info(strBuilder.toString());

Poorly worded explanation: The error is because the JS -> Java engine, Rhino, is trying to figure out what to do with strBuilder to cast it to a string type for logger.info. strBuilder has a toString method but it's also a StringBuilder object. Rhino is saying it can't figure out what to do, so you have to be explicit.