1.2 Java Thread Programming

There are two ways to create a new class that can have a thread running within it. One way is to extend the Thread class. The other is to extend any class and implement the Runnable interface. For the sake of illustration, extending Thread is the simplest approach and is initially used in this book. Implementing the Runnable interface tends to work much better in the real world; this technique is introduced in Chapter 4, "Implementing Runnable Versus Extending Thread."

Thread support the creation of two categories:

Implementation Runnable interface, from any category Gejicheng
Thread of succession

The first approach is more flexible

The steps to spawn a new thread in this chapter's example are

• Extend the java.lang.Thread class.

• Override the run () method in this subclass of Thread.

• Create an instance of this new class.

• Invoke the start () method on the instance

Create a thread steps:

Java.lang.Thread class inheritance
Covering sub-category of the run () method
Create a new instance of the class
Call examples start () method

A call to start () returns right away and does not wait for the other thread to begin execution. In start (), the parent thread asynchronously signals through the JavaVM that the other thread should be started as soon as it's convenient for the thread scheduler. At some unpredictable time in the very near future, the other thread will come alive and invoke the run () method of the Thread object (or in this case, the overridden run () method implemented in TwoThread). Meanwhile, the original thread is free to continue executing the statements that follow the start () call.

Father-threaded asynchronous operation, call start () thread of the implementation time of uncertainty

Important to note is that although the order in which each thread will execute its own statements is known and straightforward, and the order in which the statements will actually be run on the processor is indeterminate, and no particular order should be counted on for program correctness.

Thread the implementation of the order, the order of implementation of the threads Uncertainty

Listing 2.1 TwoThread.java-The Complete Code for the TwoThread Example
1: public class TwoThread extends Thread (
2: public void run () (
3: for (int i = 0; i <10; i + +) (
4: System.out.println ( "New thread");
5:)
6:)
7:
8: public static void main (String [] args) (
9: TwoThread tt = new TwoThread ();
10: tt.start ();
11:
12: for (int i = 0; i <10; i + +) (
13: System.out.println ( "Main thread");
14:)
15:)
16:)