Showing posts from December, 2015

Running Java in a Script

Recently I wanted to invoke a JMX operation in a WSO2 server from a script. I was first thinking of writing a simple Java class with a main method and run it as an executable jar file.

Then I found that we can run a script with the command "jrunscript".

I also found an example of interacting with a JMX MBean from Javascript. However this example didn't work with Java 8.

The reason is that from Java 8, the JavaScript Engine for the JVM is Oracle Nashorn. In Java 7, the JavaScript Engine is based on Mozilla Rhino.

Let's see the difference:

Following script works with Java 7, but not with Java 8

packages = new JavaImporter(java.lang, java.lang.reflect); with (packages) { // create Java String array of 5 elements var a = Array.newInstance(String, 5); // Accessing elements and length access is by usual Java syntax a[0] = "scripting is great!"; print(a.length); print('\n'); print(a[0]); print('\n'); }

Following is the…