Singleton design pattern in core java

[Praveen Kumar]

Hi,


Today I have been asked some examples of singleton design patterns in core java. But I could not able to get any examples. Please tell me if you know anything :-)

[Winston Gutkowski]

Praveen Kumar wrote:Today I have been asked some examples of singleton design patterns in core java. But I could not able to get any examples. Please tell me if you know anything :-)

I presume you mean classes, not patterns.

The only one that springs readily to my mind is Runtime (java.lang.Runtime).

Winston

[Stephan van Hulst]

Not sure if the logging framework is included, but java.util.logging.LogManager is a singleton, I believe, and java.util.logging.Logger is instance controlled. java.awt.Toolkit is also singleton. Those are the only examples I can think of right now.

[Manuel Petermann]

java.awt.Toolkit is an abstract baseclass but it is most definitifely not a singleton.

Ok my fault. Its sort of a mingleton. I think you could argue about that too because a singleton or derivates must always return the same Object but you can change the returned Object of the Toolkit.getDefaultToolkit method.

[Stephan van Hulst]

Actually, you're right. I missed the public constructor in Toolkit. It's not singleton.