Is there something like python's interactive REPL mode, but for Java?

Question

Is there something like python\'s interactive REPL mode, but for Java? So that I can, for example, type InetAddress.getAllByName( localHostName ) in a window, a

Answer 1

For folks with access to Mathematica, JLink lets you access Java and script with Mathematica code:

Needs["JLink`"]
LoadJavaClass["java.net.InetAddress"]
InetAddress`getAllByName["localhost"]

Hit Shift-Enter to evaluate, and you get

{<<JavaObject[java.net.Inet4Address>>}

Then you can use Mathematica's Map function to call toString on the returned objects:

#@toString[]& /@ %

to get the result (or to use the less obscure syntax, Map[Function[obj, obj@toString[]], %]):

{"localhost/127.0.0.1"}

If you start to get serious with this, you'll want to read Todd Gayley's tutorial at http://reference.wolfram.com/mathematica/JLink/tutorial/Overview.html.

Answer 2

You could take a look at BlueJ which is an interactive Java development environment meant for teaching OOP rather than as full IDE like Eclipse or NetBeans. It's kind of fun to have a play with anyway.

You can see it in action on YouTube in a series of Java tutorials.

Answer 3

JPad is a java scratchpad with a builtin REPL:

C:\>jpad
       _ _____          _
      | |  __ \        | |
      | | |__) |_ _  __| |
  _   | |  ___/ _` |/ _` |
 | |__| | |  | (_| | (_| |
  \____/|_|   \__,_|\__,_|



Anything you type is evaluated as java.
The code is continuously appended until you call \clear.
Other Available Commands:
\exit - exit
\clear (n) - clear past java statements
\history - display all past java statements
\help - display this help

j>2+2
4
j>Math.sin(100.1)
-0.4177477
j>

It is also smart about dumping collections, lists, maps etc and allows rendering them as a table or chart:

Answer 4

You can use Eclipse Scrapbook pages.

In Eclipse create a Scrapbook page. In your project, New->Other->Scrapbook page.

In the file, enter some text, select it and hit ctrl-U, and there you go.

To manage your imports, right click in the page and select Set Imports, where you can choose to import a package or a single class. This is persistent, and is saved with the page.