How do I import Java package in script?

Here you can see how to import a Java class so that you can use the class, creates an instance of
it in the scripting environment. We want to print out the current date on the console. For this we
need to import the Date class that’s packaged under the java.util package.

In the script we can import the java.util package using the following script
importPackage(java.util).

package org.kodejava.example.script;

import javax.script.ScriptEngineManager;
import javax.script.ScriptEngine;
import javax.script.ScriptException;

public class ImportPackageExample {
    public static void main(String[] args) {
        ScriptEngineManager manager = new ScriptEngineManager();
        ScriptEngine engine = manager.getEngineByExtension("js");

        try {
            engine.eval(getScript());
        } catch (ScriptException e) {
            e.printStackTrace();
        }
    }

    private static String getScript() {
        StringBuilder sb = new StringBuilder();
        sb.append("importPackage(java.util);");
        sb.append("");
        sb.append("var today = new Date();");
        sb.append("println('Today is ' + today);");
        return sb.toString();
    }
}

This program prints the following line:

Today is Fri Sep 11 2009 17:03:02 GMT+0800 (CST)

How do I modified Java object in script?

This example show how to modified Java object from scripting environment. Below we manipulate a collection of string data. To pass data into the scripting engine we use a key-value binding to the script engine.

package org.kodejava.example.script;

import javax.script.ScriptEngineManager;
import javax.script.ScriptEngine;
import javax.script.ScriptException;
import java.util.Date;
import java.util.List;
import java.util.ArrayList;

public class ModifiedJavaObjectFromScript {
    public static void main(String[] args) {
        //
        // Creating an array of five colors
        //
        List colors = new ArrayList();
        colors.add("White");
        colors.add("Black");
        colors.add("Red");
        colors.add("Green");
        colors.add("Blue");
        
        //
        // Obtain a ScriptEngine instance.
        //
        ScriptEngineManager manager = new ScriptEngineManager();
        ScriptEngine engine = manager.getEngineByExtension("js");

        //
        // Place the colors list into the engine using colorList key.
        // After setting the list into the engine our script will be
        // able to read it.
        //
        engine.put("colorList", colors);
        
        try {
            engine.eval(getScript());
            
            //
            // Redisplay the modified version of colors list object.
            //
            for (String color : colors) {
                System.out.println("Color = " + color);
            }
        } catch (ScriptException e) {
            e.printStackTrace();
        }
    }

    private static String getScript() {
        //
        // Below is our script to read the values of Java List that
        // contains string of colors. We also add some other colors
        // to the list object in the script environment.
        //
        String script =
                "var index; " +
                "var colors = colorList.toArray(); " +
                " " +
                "for (index in colors) { " +
                "    println(colors[index]); " +
                "}" +
                " " +
                "colorList.add("Yellow"); " +
                "colorList.add("Purple"); " +
                "colorList.add("Orange"); ";
        return script;
    }
}