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currentThread()方法

• 该方法可返回代码段正在被哪个线程调用的信息
• 代码示例

/** * Created with IntelliJ IDEA. * Description: If you don't work hard, you will a loser. * User: Listen-Y. * Date: 2020-09-28 * Time: 21:54 */public class CurrentThreadTest extends Thread{
       public CurrentThreadTest() {
           System.out.println("构造方法name:" + Thread.currentThread().getName());    }    @Override    public void run() {
           System.out.println("run方法name:" + Thread.currentThread().getName());    }}

/** * Created with IntelliJ IDEA. * Description: If you don't work hard, you will a loser. * User: Listen-Y. * Date: 2020-09-28 * Time: 21:55 */public class Run {
       public static void main(String[] args) {
           CurrentThreadTest threadTest = new CurrentThreadTest();        System.out.println("main方法name:" + Thread.currentThread().getName());        threadTest.start();    }}

• 在构造方法中输出的依旧是mian 但是在run方法输出的就是thread-0

isAlive()方法

• 判断当前线程是否处于活动状态
• 代码示例

public class IsAliveTest extends Thread {
       @Override    public void run() {
           System.out.println("run=" + this.isAlive());    }}

public class Run2 {
       public static void main(String[] args) throws InterruptedException {
           IsAliveTest test = new IsAliveTest();        System.out.println("begin=" + test.isAlive());        test.start();        Thread.sleep(100);        System.out.println("end=" + test.isAlive());    }}

使用this和Thread.currentThread的差异

• 代码

/** * Created with IntelliJ IDEA. * Description: If you don't work hard, you will a loser. * User: Listen-Y. * Date: 2020-09-28 * Time: 22:07 */public class CountOperate extends Thread {
       public CountOperate() {
           System.out.println("CountOperate构造方法Begin");        System.out.println("Thread.currentThread().getName()=" + Thread.currentThread().getName());        System.out.println("Thread.currentThread().isAlive()=" + Thread.currentThread().isAlive());        System.out.println("this.getName()=" + this.getName());        System.out.println("this.isAlive()=" + this.isAlive());        System.out.println("CountOperate构造方法End");        System.out.println();    }    @Override    public void run() {
           System.out.println("Run方法Begin");        System.out.println("Thread.currentThread().getName()=" + Thread.currentThread().getName());        System.out.println("Thread.currentThread().isAlive()=" + Thread.currentThread().isAlive());        System.out.println("this.getName()=" + this.getName());        System.out.println("this.isAlive()=" + this.isAlive());        System.out.println("Run方法End");        System.out.println();    }}

/** * Created with IntelliJ IDEA. * Description: If you don't work hard, you will a loser. * User: Listen-Y. * Date: 2020-09-28 * Time: 22:13 */public class Run3 {
       public static void main(String[] args) {
           CountOperate countOperate = new CountOperate();        Thread thread = new Thread(countOperate);        System.out.println("main begin thread isAlive=" + thread.isAlive());        thread.setName("AAA");        thread.start();        System.out.println("main end thread isAlive=" + thread.isAlive());    }}

CountOperate构造方法BeginThread.currentThread().getName()=mainThread.currentThread().isAlive()=truethis.getName()=Thread-0this.isAlive=()falseCountOperate构造方法Endmain begin thread isAlive=falsemain end thread isAlive=trueRun方法BeginThread.currentThread().getName()=AAAThread.currentThread().isAlive()=truethis.getName()=Thread-0this.isAlive()=falseRun方法EndProcess finished with exit code 0

分析问题就是我们将线程对象已构造参数的形式传递给Thread对象时进行start启动时, 使用Thread.currentThread()和this或者的信息是不一样的, 这也证实我们CurrentThread方法的使用, 因为我们是将一个线程对象传递给一个线程thread, 那我们启动的时候启动的是thread这个线程, 执行的是被传递的这个线程的run方法, 所以我们在这个对象中使用this的时候, 获得的是这个没有被启动的线程对象的信息, 使用Thread.currentThread的时候, 获得的是调用这个代码段的线程的信息, 也就是thread的信息

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