An implementation of the ThreadFactory interface that provides some configuration options for the threads it creates.

A ThreadFactory is used for instance by an ExecutorService to create the threads it uses for executing tasks. In many cases users do not have to care about a ThreadFactory because the default one used by an ExecutorService will do. However, if there are special requirements for the threads, a custom ThreadFactory has to be created.

This class provides some frequently needed configuration options for the threads it creates. These are the following:

• A name pattern for the threads created by this factory can be specified. This is often useful if an application uses multiple executor services for different purposes. If the names of the threads used by these services have meaningful names, log output or exception traces can be much easier to read. Naming patterns are format strings as used by the String.format() method. The string can contain the place holder %d which will be replaced by the number of the current thread (ThreadFactoryImpl keeps a counter of the threads it has already created). For instance, the naming pattern "My %d. worker thread" will result in thread names like "My 1. worker thread", "My 2. worker thread" and so on.
• A flag whether the threads created by this factory should be daemon threads. This can impact the exit behavior of the current Java application because the JVM shuts down if there are only daemon threads running.
• The priority of the thread. Here an integer value can be provided. The java.lang.Thread class defines constants for valid ranges of priority values.
• The UncaughtExceptionHandler for the thread. This handler is called if an uncaught exception occurs within the thread.

BasicThreadFactory wraps another thread factory which actually creates new threads. The configuration options are set on the threads created by the wrapped thread factory. On construction time the factory to be wrapped can be specified. If none is provided, a default ThreadFactory is used.

Instances of BasicThreadFactory are not created directly, but the nested Builder class is used for this purpose. Using the builder only the configuration options an application is interested in need to be set. The following example shows how a BasicThreadFactory is created and installed in an ExecutorService:

 // Create a factory that produces daemon threads with a naming pattern and
 // a priority
 BasicThreadFactory factory = new BasicThreadFactory.Builder()
     .namingPattern("workerthread-%d")
     .daemon(true)
     .priority(Thread.MAX_PRIORITY)
     .build();
 // Create an executor service for single-threaded execution
 ExecutorService exec = Executors.newSingleThreadExecutor(factory);