在Java中实现可运行与扩展线程
我们可以通过实现可运行的接口或扩展Thread类来创建Thread。以下是使用两种方式创建线程的详细步骤。
通过实现可运行接口创建线程
如果您的类打算作为线程执行，则可以通过实现Runnable接口来实现。您将需要遵循三个基本步骤-
步骤1
第一步，您需要实现Runnable接口run()提供的方法。该方法为线程提供了一个入口点，您将把完整的业务逻辑放入该方法中。以下是方法的简单语法-run()
public void run( )
第2步
第二步，您将使用以下构造函数实例化Thread对象-
Thread(Runnable threadObj, String threadName);
其中，threadObj是实现Runnable接口的类的实例，而threadName是赋予新线程的名称。
第三步
创建Thread对象后，您可以通过调用start()方法来启动它，该方法执行对run()方法的调用。以下是start()方法的简单语法-
void start();
示例
这是一个创建新线程并开始运行它的示例-
class RunnableDemo implements Runnable {
private Thread t;
private String threadName;
RunnableDemo( String name) {
threadName = name;
System.out.println("Creating " + threadName );
}
public void run() {
System.out.println("Running " + threadName );
try {
for(int i = 4; i > 0; i--) {
System.out.println("Thread: " + threadName + ", " + i);
//让线程休眠一会儿。
Thread.sleep(50);
}
} catch (InterruptedException e) {
System.out.println("Thread " + threadName + " interrupted.");
}
System.out.println("Thread " + threadName + " exiting.");
}
public void start () {
System.out.println("Starting " + threadName );
if (t == null) {
t = new Thread (this, threadName);
t.start ();
}
}
}
public class TestThread {
public static void main(String args[]) {
RunnableDemo R1 = new RunnableDemo( "Thread-1");
R1.start();
RunnableDemo R2 = new RunnableDemo( "Thread-2");
R2.start();
}
}这将产生以下结果-
输出结果
Creating Thread-1 Starting Thread-1 Creating Thread-2 Starting Thread-2 Running Thread-1 Thread: Thread-1, 4 Running Thread-2 Thread: Thread-2, 4 Thread: Thread-1, 3 Thread: Thread-2, 3 Thread: Thread-1, 2 Thread: Thread-2, 2 Thread: Thread-1, 1 Thread: Thread-2, 1 Thread Thread-1 exiting. Thread Thread-2 exiting.
通过扩展线程类创建线程
创建线程的第二种方法是使用以下两个简单步骤创建一个扩展Thread类的新类。这种方法在处理使用Thread类中的可用方法创建的多个线程时提供了更大的灵活性。
步骤1
您将需要重写Thread类中可用的run()方法。该方法为线程提供了一个入口点，您将把完整的业务逻辑放入该方法中。以下是run()方法的简单语法-
public void run( )
第2步
创建线程对象后，可以通过调用start()方法来启动它，该方法执行对run()方法的调用。以下是start()方法的简单语法-
void start( );
示例
这是前面的程序，它被重写以扩展Thread-
class ThreadDemo extends Thread {
private Thread t;
private String threadName;
ThreadDemo( String name) {
threadName = name;
System.out.println("Creating " + threadName );
}
public void run() {
System.out.println("Running " + threadName );
try {
for(int i = 4; i > 0; i--) {
System.out.println("Thread: " + threadName + ", " + i);
//让线程休眠一会儿。
Thread.sleep(50);
}
} catch (InterruptedException e) {
System.out.println("Thread " + threadName + " interrupted.");
}
System.out.println("Thread " + threadName + " exiting.");
}
public void start () {
System.out.println("Starting " + threadName );
if (t == null) {
t = new Thread (this, threadName);
t.start ();
}
}
}
public class TestThread {
public static void main(String args[]) {
ThreadDemo T1 = new ThreadDemo( "Thread-1");
T1.start();
ThreadDemo T2 = new ThreadDemo( "Thread-2");
T2.start();
}
}这将产生以下结果-
输出结果
Creating Thread-1 Starting Thread-1 Creating Thread-2 Starting Thread-2 Running Thread-1 Thread: Thread-1, 4 Running Thread-2 Thread: Thread-2, 4 Thread: Thread-1, 3 Thread: Thread-2, 3 Thread: Thread-1, 2 Thread: Thread-2, 2 Thread: Thread-1, 1 Thread: Thread-2, 1 Thread Thread-1 exiting. Thread Thread-2 exiting.