Why I can not create package name like java.basic?

Question

package java.basic;

public class Test {

    public static void main(String[] args) {

        int जानिए = 7;

        System.out.println(जानिए);

    }


}

Above class is compiling but after running getting exception

java.lang.SecurityException: Prohibited package name: java.basic
    at java.lang.ClassLoader.preDefineClass(Unknown Source)
    at java.lang.ClassLoader.defineClassCond(Unknown Source)
    at java.lang.ClassLoader.defineClass(Unknown Source)
    at java.security.SecureClassLoader.defineClass(Unknown Source)
    at java.net.URLClassLoader.defineClass(Unknown Source)
    at java.net.URLClassLoader.access$000(Unknown Source)
    at java.net.URLClassLoader$1.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(Unknown Source)
    at java.lang.ClassLoader.loadClass(Unknown Source)
    at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
    at java.lang.ClassLoader.loadClass(Unknown Source)
Exception in thread "main"

This is dumb question for one who knows class loader architecture and security :) — Neel Salpe, Dec 28 '13 at 17:57
http://stackoverflow.com/questions/3804442/why-java-lang-securityexception-prohibited-package-name-java-is-required — Sotirios Delimanolis, Dec 28 '13 at 17:58
try changing your name to "Barack Obama" and apply for a Washington D.C. driver's license... — Marc B, Dec 28 '13 at 18:00
Please look on http://stackoverflow.com/questions/533102/what-strategy-do-you-use-for-package-naming-in-java-projects-and-why?rq=1 — Rakesh KR, Dec 28 '13 at 18:00
As this question has already been asked before more than twice, i think it is better to be closed as Duplicate — Sage, Dec 28 '13 at 18:03

score 2 · Answer 1 · answered Dec 28 '13 at 18:00

2

See the docs:

Packages in the Java language itself begin with java. or javax.

java. is not for you, the English alphabet has 26 letters. Use them to generate names other than java.

Also see java.lang:

Provides classes that are fundamental to the design of the Java programming language.

It's for Java code, and it's imported by default in every code.

answered Dec 28 '13 at 18:00

Maroun

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Do packages have to be written with english characters? – Sotirios Delimanolis Dec 28 '13 at 18:02
The docs doesn't mention any restriction about that.. But I think we should all write in English since that's how the world is communicating :) at least for now.. – Maroun Dec 28 '13 at 18:04

score 2 · Answer 2 · answered Dec 28 '13 at 18:01

Because otherwise your classes will get access to default (no modifiers) / protected members of standard JDK classes which are not meant to expose its internal details to the developer.

Prohibiting custom classes in java.* packages forbids you from exploiting such thing.

score 1 · Answer 3 · answered Dec 28 '13 at 18:00

1

Allowing the use of a user created package named java would allow access to package-private fields, methods and constructors.

answered Dec 28 '13 at 18:00

Troubleshoot

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score 1 · Answer 4 · edited May 27 '15 at 18:54

1

java is a reserved package name. Only classes inside the JVM can reside in this package.

If anyone could write in the java package, that could result in libraries arbitrarily replacing core Java classes with their own implementations. That could result in a lot of things, from breaking core Java features to execution of malicious code.

edited May 27 '15 at 18:54

Nayuki

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answered Dec 28 '13 at 18:02

Rakesh KR

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Why I can not create package name like java.basic?

4 Answers4