目录
Thread的常见构造方法
Thread的常见属性
代码示例1
代码示例2
示例代码3
代码示例4
代码示例5
小结
线程中断
代码示例1
代码示例2
代码示例3
代码示例4
小结
线程等待
获取当前线程的引用
Thread的常见构造方法
举例
Thread t1 = new Thread();
Thread t2 = new Thread(new MyRunnable());
Thread t3 = new Thread("这是我的名字");
Thread t4 = new Thread(new MyRunnable(), "这是我的名字");
代码示例
public class Demo06 {public static void main(String[] args) {Thread t=new Thread(()->{while(true){System.out.println("hello thread");try {Thread.sleep(1000);} catch (InterruptedException e) {throw new RuntimeException(e);}}},"这是新线程");t.start();}
}
通过jconsole.exe观察
Thread的常见属性
属性 | 获取方法 |
ID | getId() |
名称 | getName() |
状态 | getState() |
优先级 | getPriority() |
是否后台进程 | isDaemon() |
是否存活 | isAlive() |
是否被中断 | isInterrupted() |
ID 是线程的唯一标识,不同线程不会重复;
名称是各种调试工具用到;
状态表示线程当前所处的一个情况;
优先级高的线程理论上来说更容易被调度到;
关于后台线程,记住一点:JVM会在一个进程的所有非后台线程结束后,才会结束运行;
是否存活,即简单的理解,为 run 方法是否运行结束了
代码示例1
public class Demo06 {public static void main(String[] args) {Thread t=new Thread(()->{while(true){System.out.println("hello thread");try {Thread.sleep(1000);} catch (InterruptedException e) {throw new RuntimeException(e);}}},"这是新线程");System.out.println(t.getId());System.out.println(t.getName());System.out.println(t.getState());System.out.println(t.getPriority());System.out.println(t.isDaemon());System.out.println(t.isAlive());System.out.println(t.isInterrupted());t.start();}
}
运行结果
代码示例2
public class Demo07 {public static void main(String[] args) throws InterruptedException {Thread t=new Thread(()->{System.out.println("线程开始");try {Thread.sleep(2000);} catch (InterruptedException e) {throw new RuntimeException(e);}System.out.println("线程结束");});System.out.println(t.isAlive());t.start();System.out.println(t.isAlive());Thread.sleep(3000);System.out.println(t.isAlive());}
}
运行结果
示例代码3
public class Demo08 {private static boolean isQuit=false;public static void main(String[] args) throws InterruptedException {Thread t=new Thread(()->{while(!isQuit){System.out.println("线程工作中");try {Thread.sleep(1000);} catch (InterruptedException e) {throw new RuntimeException(e);}}System.out.println("线程工作完毕!");});t.start();Thread.sleep(5000);isQuit=true;System.out.println("设置 isQuit 为 true");}
}
运行结果
代码示例4
public class Demo09 {public static void main(String[] args) throws InterruptedException {Thread t=new Thread(()->{//Thread类内部有一个标志位,可以用来判定当前的循环是否要结束while(!Thread.currentThread().isInterrupted()){System.out.println("线程工作中");try {Thread.sleep(1000);} catch (InterruptedException e) {//throw new RuntimeException(e);//1.假装没听见,循环继续正常执行e.printStackTrace();//2.加上一个bread,表示让线程立即结束//break;//3.做一些其它工作,完成之后再结束break;}}});t.start();Thread.sleep(5000);System.out.println("让 t 线程终止");t.interrupt();}
}
运行结果
代码示例5
public class Demo10 {public static void main(String[] args) throws InterruptedException {Thread t=new Thread(()->{for (int i = 0; i < 5; i++) {System.out.println("t 线程工作中");try {Thread.sleep(1000);} catch (InterruptedException e) {throw new RuntimeException(e);}}});t.start();System.out.println("join 等待开始");t.join();System.out.println("join 等待结束");}
}
小结
上面的代码是让主线程来等待 t 线程执行结束,一旦调用 join,主线程就会触发阻塞,此时 t 线程就可以趁机完成后续的工作,一直到阻塞到 t 执行完毕,join才会解除阻塞。
即:哪个线程调用 join(),哪个线程就会被阻塞。
代码示例6
public class Demo11 {public static void main(String[] args) throws InterruptedException {Thread t=new Thread(()->{while(true){try {Thread.sleep(1000);} catch (InterruptedException e) {throw new RuntimeException(e);}}});System.out.println(t.getState());t.start();for (int i = 0; i < 5; i++) {System.out.println(t.getState());Thread.sleep(1000);}System.out.println(t.getState());}
}
运行结果
线程中断
常见的两种方式:
1.通过共享的标记来进行沟通;
2.调用 interrupt() 方法来通知。
代码示例1
public class Demo11 {private static class MyRunnable implements Runnable{public volatile boolean isQuit=false;@Overridepublic void run() {while(!isQuit) {System.out.println("开始");try {Thread.sleep(1000);} catch (InterruptedException e) {throw new RuntimeException(e);}}System.out.println("结束");}}public static void main(String[] args) throws InterruptedException {MyRunnable target=new MyRunnable();Thread t=new Thread(target);t.start();Thread.sleep(5000);target.isQuit=true;}
}
运行结果
代码示例2
public class Demo11 {private static class MyRunnable implements Runnable{@Overridepublic void run() {while(!Thread.interrupted()) {System.out.println("开始");try {Thread.sleep(1000);} catch (InterruptedException e) {throw new RuntimeException(e);}}System.out.println("结束");}}public static void main(String[] args) throws InterruptedException {MyRunnable target=new MyRunnable();Thread t=new Thread(target);t.start();Thread.sleep(5000);t.interrupt();}
}
运行结果
代码示例3
public class Demo11 {private static class MyRunnable implements Runnable{@Overridepublic void run() {while(true){System.out.println(Thread.currentThread().isInterrupted());}}}public static void main(String[] args) throws InterruptedException {MyRunnable target=new MyRunnable();Thread t=new Thread(target);t.start();Thread.sleep(2000);t.interrupt();}
}
运行结果
代码示例4
public class Demo11 {private static class MyRunnable implements Runnable{@Overridepublic void run() {while(true){System.out.println(Thread.interrupted());}}}public static void main(String[] args) throws InterruptedException {MyRunnable target=new MyRunnable();Thread t=new Thread(target);t.start();Thread.sleep(2000);t.interrupt();}
}
运行结果
小结
如果线程因为调用wait/join/sleep等方法而阻塞挂起,则以InterruptedException异常的形式通知,清除中断标志,当出现InterruptedException的时候,要不要结束线程取决于catch中代码的写法,可以选择忽略这个异常,也可以选择跳出循环结束线程;
1.Thread.interrupted()判断当前线程的中断标志被设置,清除中断标志;
2.Thread.currentThread().isInterrupted()判断指定线程的中断标志被设置,不清楚中断标志;
这两种方法通知收到的更及时,及时线程正在sleep也可以马上收到。
线程等待
获取当前线程的引用
方法 | 属性 |
public static Thread currentThread() | 返回当前线程对象的引用 |
public class ThreadDemo {public static void main(String[] args) {Thread thread = Thread.currentThread();System.out.println(thread.getName());}}