Java 简明教程
Java - Starting a Thread
Starting a Thread
一旦创建了 Thread 对象，就可以通过调用 start() method来启动它，该调用会执行对 run() method的调用。以下是 start() 方法的简单语法 –
Once a Thread object is created, you can start it by calling start() method, which executes a call to run() method. Following is a simple syntax of start() method −
void start();Syntax of Starting a Thread
以下是启动线程的语法 -
The following is the syntax of starting a thread -
thread_obj.start();此处，thread_obj 是 Thread class的对象，start() 是 Thread 类的使用方法。
Here, thread_obj is an object to the Thread class, and start() is the method of the Thread class.
Start a Thread by Implementing Runnable Interface
在本示例中，我们通过实现 Runnable 接口来创建一个类 RunnableDemo。RunnableDemo 类具有 run() 方法实现。在 main 类 TestThread 中，我们创建了 RunnableDemo 对象，并且使用这些对象我们创建了两个 Thread 对象。在每个线程对象上调用 Thread.start() 方法时，线程开始处理并且执行程序。
In this example, we’re creating a class RunnableDemo by implementing Runnable interface. RunnableDemo class has run() method implementation. In main class TestThread, we’ve created the RunnableDemo objects and using those objects we’ve created two Thread objects. When Thread.start() method is called on each thread objects, threads start processing and program is executed.
Example
package com.tutorialspoint;
class RunnableDemo implements Runnable {
private String threadName;
RunnableDemo( String name) {
threadName = name;
System.out.println("Thread: " + threadName + ", " + "State: New");
}
public void run() {
System.out.println("Thread: " + threadName + ", " + "State: Running");
for(int i = 4; i > 0; i--) {
System.out.println("Thread: " + threadName + ", " + i);
}
System.out.println("Thread: " + threadName + ", " + "State: Dead");
}
}
public class TestThread {
public static void main(String args[]) {
RunnableDemo runnableDemo1 = new RunnableDemo( "Thread-1");
RunnableDemo runnableDemo2 = new RunnableDemo( "Thread-2");
Thread thread1 = new Thread(runnableDemo1);
Thread thread2 = new Thread(runnableDemo2);
thread1.start();
thread2.start();
}
}Thread: Thread-1, State: New
Thread: Thread-2, State: New
Thread: Thread-1, State: Running
Thread: Thread-1, 4
Thread: Thread-1, 3
Thread: Thread-1, 2
Thread: Thread-1, 1
Thread: Thread-1, State: Dead
Thread: Thread-2, State: Running
Thread: Thread-2, 4
Thread: Thread-2, 3
Thread: Thread-2, 2
Thread: Thread-2, 1
Thread: Thread-2, State: DeadStart a Thread by Extending Thread Class
下面是对继承 Thread 的程序的重写 - 在本示例中，我们创建了一个扩展 Thread 类的 ThreadDemo 类。我们在 constructor() 方法中调用 super(name) 为线程分配一个名称，并且调用 super.start() 来启动线程处理。
Here is the preceding program rewritten to extend the Thread − In this example, we’ve created a ThreadDemo class which extends Thread class. We’re calling super(name) in constructor() method to assign a name to the thread and called super.start() to start the thread processing.
Example
package com.tutorialspoint;
class ThreadDemo extends Thread {
ThreadDemo( String name) {
super(name);
System.out.println("Thread: " + name + ", " + "State: New");
}
public void run() {
System.out.println("Thread: " + Thread.currentThread().getName() + ", " + "State: Running");
for(int i = 4; i > 0; i--) {
System.out.println("Thread: " + Thread.currentThread().getName() + ", " + i);
}
System.out.println("Thread: " + Thread.currentThread().getName() + ", " + "State: Dead");
}
public void start () {
System.out.println("Thread: " + Thread.currentThread().getName() + ", " + "State: Start");
super.start();
}
}
public class TestThread {
public static void main(String args[]) {
ThreadDemo thread1 = new ThreadDemo( "Thread-1");
ThreadDemo thread2 = new ThreadDemo( "Thread-2");
thread1.start();
thread2.start();
}
}Thread: Thread-1, State: New
Thread: Thread-2, State: New
Thread: Thread-1, State: Running
Thread: Thread-1, 4
Thread: Thread-1, 3
Thread: Thread-1, 2
Thread: Thread-1, 1
Thread: Thread-1, State: Dead
Thread: Thread-2, State: Running
Thread: Thread-2, 4
Thread: Thread-2, 3
Thread: Thread-2, 2
Thread: Thread-2, 1
Thread: Thread-2, State: DeadStart a Thread (with Demonstrating sleep() method)
在此示例中，我们创建 ThreadDemo 类的几个对象，它扩展了 Thread 类。我们在 constructor() 方法中调用 super(name) 以为线程分配名称，并调用 super.start() 来启动线程处理。使用 sleep() method，我们在处理中引入延迟。
In this example, we’re creating couple of objects of ThreadDemo class which extends Thread class. We’re calling super(name) in constructor() method to assign a name to the thread and called super.start() to start the thread processing. Using sleep() method, we’re introducing the delay in processing.
Example
package com.tutorialspoint;
class ThreadDemo extends Thread {
ThreadDemo( String name) {
super(name);
System.out.println("Thread: " + name + ", " + "State: New");
}
public void run() {
System.out.println("Thread: " + Thread.currentThread().getName() + ", " + "State: Running");
for(int i = 4; i > 0; i--) {
System.out.println("Thread: " + Thread.currentThread().getName() + ", " + i);
try {
Thread.sleep(50);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
System.out.println("Thread: " + Thread.currentThread().getName() + ", " + "State: Dead");
}
public void start () {
System.out.println("Thread: " + Thread.currentThread().getName() + ", " + "State: Start");
super.start();
}
}
public class TestThread {
public static void main(String args[]) {
ThreadDemo thread1 = new ThreadDemo( "Thread-1");
ThreadDemo thread2 = new ThreadDemo( "Thread-2");
thread1.start();
thread2.start();
}
}Thread: Thread-1, State: New
Thread: Thread-2, State: New
Thread: main, State: Start
Thread: main, State: Start
Thread: Thread-1, State: Running
Thread: Thread-1, 4
Thread: Thread-2, State: Running
Thread: Thread-2, 4
Thread: Thread-2, 3
Thread: Thread-1, 3
Thread: Thread-1, 2
Thread: Thread-2, 2
Thread: Thread-2, 1
Thread: Thread-1, 1
Thread: Thread-1, State: Dead
Thread: Thread-2, State: Dead