What does the Type parameter for Thread and Runnable signify?

Question

Look at the following code from the ThreadFactory interface

 public Thread<T> newThread(Runnable<T> runnable);

What does s the type parameter convey here ? I mean Collection makes sense since T is specifying the type of objects that can go into the Collection but what does Runnable or Thread mean ?

Where did you see that code? It says [`Thread newThread(Runnable r)`](http://docs.oracle.com/javase/1.5.0/docs/api/java/util/concurrent/ThreadFactory.html#newThread(java.lang.Runnable)). — Marko Topolnik, Jul 10 '12 at 12:15
@MarkoTopolnik first answer in http://stackoverflow.com/questions/5762991/how-does-java-util-concurrent-executor-work/5766067 — Inquisitive, Jul 10 '12 at 12:18
@Subhra If you actually look up the ThreadFactory code from Oracle, not once does it mention templatisation. — Nathan White, Jul 10 '12 at 12:19
Subhra, that guy was obviously typing from memory. As you say it's meaningless and indeed it is not real. — Marko Topolnik, Jul 10 '12 at 12:23
@nathanwhite please see the source of that code in the link I gave in another comment above — Inquisitive, Jul 10 '12 at 12:23
@Subhra I did, but then the first person to get it wrong simply influenced a second person to get it wrong. If it's not on Oracles website as that, it isn't the case. — Nathan White, Jul 10 '12 at 12:26

score 4 · Accepted Answer · answered Jul 10 '12 at 12:26

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In ThreadFactory.newThread(Runnable) there is no generic type, nor is Runnable or Thread a generic interface/class. The original must have been in error.

answered Jul 10 '12 at 12:26

Peter Lawrey

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score 0 · Answer 2 · edited May 23 '17 at 10:09

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Thread class you are creating,it has to be the subclass of some other class, it can’t extend from the Thread class. This is because Java does not allow a class to inherit from more than one class. That's why Runnable interface to implement threads.

For better understanding,just take a look of these two links this1 and this2

edited May 23 '17 at 10:09

Community

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answered Jul 10 '12 at 12:25

Tirtha

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Its not clear how this related to the OP's question about generics? – Peter Lawrey Jul 10 '12 at 12:27
I'm talking about thread implementation with runnable interface. – Tirtha Jul 10 '12 at 13:00

score 0 · Answer 3 · answered Jul 10 '12 at 12:27

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It does not look like Runnable this was intended with the Runnable interface. Maybe you are getting confused with Callable. Here the generic type will be the type returned.

answered Jul 10 '12 at 12:27

John Kane

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I am not confused with Callable . Please see the [source of this code here in SO](http://stackoverflow.com/questions/5762991/how-does-java-util-concurrent-executor-work/5766067) . – Inquisitive Jul 10 '12 at 12:28
That was probably just a mistake. – John Kane Jul 10 '12 at 12:30

What does the Type parameter for Thread and Runnable signify?

3 Answers3