Importing Java Classes in Clojure

Question

I seem to be doing something wrong. I've built clojure from git, and am invoking it thus:

java -cp clojure.jar clojure.main

I get the repl, and then I type:

(import 'java.lang.string)

and I get:

java.lang.ClassNotFoundException: java.lang.string (NO_SOURCE_FILE:1)

I'm trying this with lang.string since I assume it has to exist on the classpath somewhere. I've tried other libraries, all without much luck. What am I doing wrong?

Brian Carper · Accepted Answer · 2010-06-24 15:42:19Z

15

String should be capitalized, that's all.

user> (import 'java.lang.String)
java.lang.String

But everything in java.lang is already imported and available by default, so you shouldn't need to do this.

answered Jun 24, 2010 at 15:42

Brian Carper

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Comments

Bozhidar Batsov · Accepted Answer · 2010-06-24 16:47:38Z

8

Btw in non repl exercises probably the best way to include Java classes is the ns macro.

(ns foo.bar
  (:refer-clojure :exclude [ancestors printf])
  (:require (clojure.contrib sql sql.tests))
  (:use (my.lib this that))
  (:import (java.util Date Timer Random)
           (java.sql Connection Statement)))

answered Jun 24, 2010 at 16:47

Bozhidar Batsov

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Comments

Timothy Baldridge · Accepted Answer · 2010-06-24 15:41:32Z

2

Bleh, I think I found it. First of all the syntax should be:

(import java.lang.String)

Also notice it's String not string.

answered Jun 24, 2010 at 15:41

Timothy Baldridge

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2 Comments

kotarak Over a year ago

No. The quote is necessary for import. See Brian's answer. But not for ns clauses. See Bozhidar's answer.

Bozhidar Batsov Over a year ago

Actually the quote is not needed for import as well. At least in clojure 1.1, that I'm using...

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