Java CallableThread is not a standard class or interface in Java, but a common design pattern where a Java Thread or a Java ExecutorService task implements the Java Callable interface. This allows for asynchronous execution of a task and returning a result once the computation is completed. CallableThread is commonly used in concurrent programming and threading environments to perform tasks that need to return a result or handle exceptions, which is more flexible than Java Runnable.

https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/Callable.html