java设置线程的优先级，java线程优先级,如果线程要执行的任务很紧

java设置线程的优先级，java线程优先级,如果线程要执行的任务很紧

如果线程要执行的任务很紧急，这时候设置线程的优先级就是很重要的。

Thread类有setPriority(int level)方法用来设置线程的优先级。

线程的有限级从1到10，1是最不重要的，10是最重要的。如果没有给线程设置优先级，那么线程的优先级将是默认值5.

下面第一个例子代码展示未设置优先级情况下的输出，

/** * Main.java * * @author byrx.net */public class Main {    /**     * Starts two threads and wait for them to finish.     */    public void setPrioritiesOnThreads() {        Thread thread1 = new Thread(new TestThread(1));        Thread thread2 = new Thread(new TestThread(2));        thread1.start();        thread2.start();        try {            //Wait for the threads to finish            thread1.join();            thread2.join();        } catch (InterruptedException ex) {            ex.printStackTrace();        }        System.out.println("Done.");    }    /**     * Starts the program     *     * @param args the command line arguments     */    public static void main(String[] args) {        new Main().setPrioritiesOnThreads();    }    class TestThread implements Runnable {        int id;        public TestThread(int id) {            this.id = id;        }        public void run() {            for (int i = 1; i <= 10; i++) {                System.out.println("Thread" + id + ": " + i);            }        }    }}

因为两个线程的优先级是一样的所以，两个线程交叉执行

Thread2: 1Thread1: 1Thread2: 2Thread1: 2Thread2: 3Thread1: 3Thread2: 4Thread1: 4Thread2: 5Thread1: 5Thread2: 6Thread1: 6Thread2: 7Thread2: 8Thread2: 9Thread2: 10Thread1: 7Thread1: 8Thread1: 9Thread1: 10Done.

如果我们设置了线程的优先级，CPU就会优先给优先级高的线程，如下代码：

/** * Main.java * * @author byrx.net */public class Main {    /**     * Starts two threads, setting priorities on them      * and wait for them to finish.     *      */    public void setPrioritiesOnThreads() {        Thread thread1 = new Thread(new TestThread(1));        Thread thread2 = new Thread(new TestThread(2));        //Setting priorities on the Thread objects        thread1.setPriority(Thread.MAX_PRIORITY);        thread2.setPriority(Thread.MIN_PRIORITY);        thread1.start();        thread2.start();        try {            //Wait for the threads to finish            thread1.join();            thread2.join();        } catch (InterruptedException ex) {            ex.printStackTrace();        }        System.out.println("Done.");    }    /**     * Starts the program     *     * @param args the command line arguments     */    public static void main(String[] args) {        new Main().setPrioritiesOnThreads();    }    class TestThread implements Runnable {        int id;        public TestThread(int id) {            this.id = id;        }        public void run() {            for (int i = 1; i <= 10; i++) {                System.out.println("Thread" + id + ": " + i);            }        }    }}

输出如下：

Thread1: 1Thread1: 2Thread1: 3Thread1: 4Thread1: 5Thread1: 6Thread1: 7Thread1: 8Thread1: 9Thread1: 10Thread2: 1Thread2: 2Thread2: 3Thread2: 4Thread2: 5Thread2: 6Thread2: 7Thread2: 8Thread2: 9Thread2: 10Done.