JavaFX interactive shell

JavaFX compiler has a built-in script shell - Per Bothner has implemented a read-eval-print loop facility for JavaFX. The script shell class is com.sun.tools.javafx.script.ScriptShell. Note:This is in the openjfx-compiler repository and not in the JavaFX 1.0 binary.

A sample JavaFX session is as follows:


$ java -cp dist/lib/shared/javafxc.jar com.sun.tools.javafx.script.ScriptShell 
/\*fx1\*/ "hello"
hello
/\*fx2\*/ 2 + 4
6
/\*fx3\*/ function greet (name) { println("Hello, {name}") }
/\*fx4\*/ greet("Sundar")
Hello, Sundar
/\*fx5\*/ var s = [ "Sunday", "Monday", "Tuesday" ]
[ Sunday, Monday, Tuesday ]
/\*fx6\*/ for (i in s) println(i) 
Sunday
Monday
Tuesday
/\*fx7\*/ class Person { public var name: String; }               
/\*fx8\*/ var p = Person { name: "Sundar" }
fx7$Person@13fba1
/\*fx9\*/ p.name
Sundar
/\*fx10\*/ import javax.swing.\*;
/\*fx11\*/ var f = new JFrame("hello");
fx11:1: cannot find symbol
symbol  : class JFrame
location: class fx11
/\*fx12\*/   
/\*fx13\*/ var f = new javax.swing.JFrame("hello")
javax.swing.JFrame[frame0,0,0,0x0,invalid,hidden,layout=java.awt.BorderLayout,title=hello,resizable,normal,defaultCloseOperation=HIDE_ON_CLOSE,rootPane=javax.swing.JRootPane[,0,0,0x0,invalid,layout=javax.swing.JRootPane$RootLayout,alignmentX=0.0,alignmentY=0.0,border=,flags=16777673,maximumSize=,minimumSize=,preferredSize=],rootPaneCheckingEnabled=true]
/\*fx14\*/ f.setSize(300, 300)
/\*fx15\*/ f.setVisible(true)

While there is a generic shell called "jrunscript" for languages that implement jsr-223, it does not work very well for statically typed languages (which can be said about jsr-223 itself). But, the above mentioned JavaFX script shell is independent of jsr-223 interface.

Besides, jrunscript crashes for JavaFX!


$ jrunscript -cp dist/lib/shared/javafxc.jar -l javafx
fx> "hello"
Exception in thread "main" java.lang.NoSuchMethodError: com.sun.tools.javac.main.RecognizedOptions.getJavacFileManagerOptions(Lcom/sun/tools/javac/main/RecognizedOptions$OptionHelper;)[Lcom/sun/tools/javac/main/JavacOption$Option;
	at com.sun.tools.javac.util.JavacFileManager.(JavacFileManager.java:973)
	at com.sun.tools.javafx.api.JavafxcTool.getStandardFileManager(JavafxcTool.java:102)
	at com.sun.tools.javafx.script.JavaFXScriptCompiler.(JavaFXScriptCompiler.java:87)
	at com.sun.tools.javafx.script.JavaFXScriptContext.(JavaFXScriptContext.java:45)
	at com.sun.tools.javafx.script.JavaFXScriptEngineImpl.getJavaFXScriptContext(JavaFXScriptEngineImpl.java:61)
	at com.sun.tools.javafx.script.JavaFXScriptEngineImpl.getJavaFXScriptContext(JavaFXScriptEngineImpl.java:55)
	at com.sun.tools.javafx.script.JavaFXScriptEngineImpl.parse(JavaFXScriptEngineImpl.java:220)
	at com.sun.tools.javafx.script.JavaFXScriptEngineImpl.eval(JavaFXScriptEngineImpl.java:173)
	at com.sun.tools.javafx.script.JavaFXScriptEngineImpl.eval(JavaFXScriptEngineImpl.java:164)
	at javax.script.AbstractScriptEngine.eval(AbstractScriptEngine.java:247)
	at com.sun.tools.script.shell.Main.evaluateString(Main.java:280)
	at com.sun.tools.script.shell.Main.processSource(Main.java:249)
	at com.sun.tools.script.shell.Main.access$100(Main.java:19)
	at com.sun.tools.script.shell.Main$1.run(Main.java:165)
	at com.sun.tools.script.shell.Main.main(Main.java:30)

This is because JavaFX compiler code depends on modified javac classes. The code for jrunscript lives in tools.jar along with the unmodified javac classes! These unmodified javac classes are loaded which results in exception from javafxc code! We have to use the bootstrap path workaround as shown below:


$ jrunscript -J-Xbootclasspath/p:./dist/lib/shared/javafxc.jar -l javafx
fx> 233 + 334
567
fx> for (i in [0..4]) println(i)
0
1
2
3
4
fx> 

But, now we have a much better ScriptShell for JavaFX :-) We don't need to resort to this hack...

Comments:

I suppose it is in the 1.1 release?
I have:
Exception in thread "main" java.lang.NoClassDefFoundError: com/sun/tools/javafx/script/ScriptShell
with the 1.0 release.

Posted by Philippe Lhoste on February 23, 2009 at 02:30 PM IST #

Hi Philippe Lhoste: I am sorry - I should have made this explicit. This is in the current code base of openjfx-compiler and not in 1.0 binary.

Posted by A. Sundararajan on February 23, 2009 at 02:38 PM IST #

Thanks for the nice and explanatory article!

Posted by Ankara Bilgisayar Bilgisayar Satis on February 26, 2009 at 10:39 AM IST #

Hi.

We have been trying to use the JythonScriptEngine in our project. We run jython scripts from within a tomcat container which can potentially spawn 100s of threads to service the requests.

Now the problem is since this engine keeps ThreadLocal PySystemStates we will end up having 100s of such states (all having the modules cached). Is there any work around for this? We would like to have a single PySystemState for all the threads. Do you think it is possible with this engine?

Any help on this will be greatly appreciated!!

thanks,
-anurag.

Posted by Anurag on March 11, 2009 at 03:40 PM IST #

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