GWT: Javascript implementation of JRE classes

Sometimes I'd like to take a peek into the implementation of the JRE classes, which is used to generate the JavaScript code.

For some classes, I can find a corresponding implementation by guessing its name, e.g. com.google.gwt.core.开发者_如何学JAVAclient.impl.StringBuilderImpl. But where's the implementation for java.util.Date for example? Where do I find it, and how does GWT find it (via some configuration file?)

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Where do I find it

A quick find on GWT trunk reveals user.super.com.google.gwt.emul.java.util.Date.java and user.super.com.google.gwt.emul.java.sql.Date.java. The user.super.com.google.gwt.emul package holds more emulated Java classes.

how does GWT find it (via some configuration file?)

The module XML file has the <super-source/> directive which tells the compiler where to find the source, relative to the module root. I'm assuming here that no parameters means that the user.super.com.google.gwt.emul becomes the "root" and thus user.super.com.google.gwt.emul.java.util.Date.java becomes java.util.Date.java (notice for example that the package specified in that emulated Data.java is not user.super.com.google.gwt.emul.java.util but java.util).