MULTITHREADING AND PARALLEL PROGRAMMING - Introduction to Java Programming: Comprehensive Version - page 1102

30.4 The Thread Class
The Thread class contains the constructors for creating threads for tasks and the
methods for controlling threads.

Key
Point

Figure 30.4 shows the class diagram for the Thread class.

«interface»
java.lang.Runnable

java.lang.Thread

+Thread() Creates an empty thread.

+Thread(task: Runnable) Creates a thread for a specified task.

+start(): void Starts the thread that causes the

run()

method to be invoked by the JVM.

+isAlive(): boolean
+setPriority(p: int): void
+join(): void

Tests whether the thread is currently running.

Sets priority (ranging from 1 to 10) for this thread.

Waits for this thread to finish.
Puts a thread to sleep for a specified time in milliseconds.
Causes a thread to pause temporarily and allow other threads to execute.

p

+sleep(millis: long): void
+yield(): void

+interrupt(): void

Interrupts this thread.

F IGURE 30.4

The Thread class contains the methods for controlling threads.

Note
Since the Thread class implements Runnable , you could define a class that extends
Thread and implements the run method, as shown in Figure 30.5a, and then create
an object from the class and invoke its start method in a client program to start the
thread, as shown in Figure 30.5b. separating task from thread

java.lang.Thread CustomThread

// Client class
public class Client {

...
public void

// Custom thread class
public class

someMethod() {

CustomThread extends Thread { ...

// Create a thread
CustomThread thread1 =

...
public CustomThread(...) {
...
}

new CustomThread(...);

// Start a thread
thread1.start();

...

// Override the run method in Runnable
public void run() {
// Tell system how to perform this task
...
}
...
}

// Create another thread
CustomThread thread2 =

new CustomThread(...);

// Start a thread
thread2.start();
}
...
}

(a) (b)

F IGURE 30.5

Define a thread class by extending the Thread class.