Introduction

What's new in java8

1. Lambda expression, one of the new features of jdk8
2. Method reference of the second new feature of jdk8
3. Three function interface of new characteristics of jdk8
4. Four default methods for new features of jdk8
5. Five new features of jdk8 Stream API
6. Six Optional classes of new features of jdk8
7. Seven new features of jdk8 Nashorn JavaScript
8. New features of jdk8 date time API
9. Nine new features of jdk8 Base64

jjs

jjs is a command-line tool based on the Nashorn engine. It takes some javaScript source code as parameters and executes the source code. For example, we create a sample.js file with the following contents:

print('Hello World!');

Open the console (navigate to the jdk/bin directory under windows), and enter the following command:

jjs sample.js

The output is:

Hello World!

jjs interactive programming

Open the console (navigate to the jdk/bin directory under windows), and enter the following command:

C:\Program Files\Java\jdk1.8.0_162\bin>jjs
jjs> print("Hello,World!")
Hello,World!
jjs> quit()

Transfer parameters

Open the console (navigate to the jdk/bin directory under windows) and enter the following command:

C:\Program Files\Java\jdk1.8.0_162\bin>jjs -- a b c
jjs> print('Letter:'+arguments.join(", "))
//Letters: a, b, c
jjs>

Calling javaScript in java

Using ScriptEngineManager, JavaScript code can be executed in Java. The example is as follows:

package com.adanblog.demo;

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

/**
 * java8 Seven new features: Nashorn JavaScript
 * @author www.adanblog.com
 *
 */
public class NashornJavaScriptTest {
	public static void main(String[] args) {
		ScriptEngineManager scriptEngineManager=new ScriptEngineManager();
		ScriptEngine scriptEngine=scriptEngineManager.getEngineByName("nashorn");
		String name="Runoob";
		Integer result=null;
		try {
			scriptEngine.eval("print('" + name + "')");
			result=(Integer)scriptEngine.eval("3+3");
		} catch (Exception e) {
			System.out.println("Script execution error: "+ e.getMessage());
		}
		System.out.println(result.toString());
	}
}

The operation output is:

Runoob
6

Calling Java in JavaScript

Add the following code to the sample.js file:

var BigDecimal = Java.type('java.math.BigDecimal');

function calculate(amount, percentage) {

   var result = new BigDecimal(amount).multiply(
   new BigDecimal(percentage)).divide(new BigDecimal("100"), 2, BigDecimal.ROUND_HALF_EVEN);
   
   return result.toPlainString();
}

var result = calculate(568000000000000000023,13.9);
print(result);

Open the console (navigate to the jdk/bin directory under windows), and enter the following command:

C:\Program Files\Java\jdk1.8.0_162\bin>jjs sample.js
Hello World!
78952000000000002017.94