Thread.aliveCount()的生命周期和Thread的生命周期一致

livend · livend · commit fe66f703abcc · 2016-07-20T21:17:47.000+08:00
diff --git a/JavaMultiThreadingCodes/src/JoiningAndSynchronizeThreads_3/Worker.java b/JavaMultiThreadingCodes/src/JoiningAndSynchronizeThreads_3/Worker.java
@@ -77,7 +77,7 @@ public void run() {
             thread1.join();                //主线程等待子线程执行完后在执行下面的sysout
             thread2.join();
         } catch (InterruptedException ignored) {
-
+            ignored.printStackTrace();
         }
         System.out.println("Count is: " + count);     //用join保证保证前面两个线程已经执行完成
     }
diff --git a/JavaMultiThreadingCodes/src/mytest_0/ThreadActiveCount.java b/JavaMultiThreadingCodes/src/mytest_0/ThreadActiveCount.java
@@ -0,0 +1,49 @@
+package mytest_0;
+
+/**
+ * @author liwen.
+ * @date 2016/7/20 18:05.
+ */
+public class ThreadActiveCount {
+
+    public static void main(String[] args) {
+         MyThread my = new MyThread();
+         MyThread my2 = new MyThread();
+         Thread t1 = new Thread(my);
+         Thread t2 = new Thread(my);
+         Thread t3 = new Thread(my);
+         Thread t4 = new Thread(my2);
+        t1.start();
+        t2.start();
+        t3.start();
+        t4.start();
+
+         Thread[] threads = new Thread[Thread.activeCount()];        //默认会有两个线程，一个main线程，一个monitor线程
+         int i = Thread.enumerate(threads);
+         System.out.println(i);
+
+         for(Thread t:threads){
+             System.out.println("hello:"+t.getName());
+         }
+
+//        t1.start();
+//        t2.start();
+//        t3.start();
+//        t4.start();
+
+    }
+}
+
+class MyThread implements Runnable{
+
+    @Override
+    public void run() {
+        System.out.println(Thread.currentThread().getName());
+    }
+}
+
+/**
+ * Thread.activeCount()计算值和线程的生命周期不一样，当线程一旦创建即使还未调用start()，会出现在activeCount中(from java-thread book) ---- 这是错误的
+ * 线程只有调用了start()方法，才会出现在activeCount中；只会显示该程序启动所用到的线程，不会显示虚拟机中的其他线程（如：垃圾回收线程）
+ * 一个线程实例只能启动一次
+ */
diff --git a/JavaMultiThreadingCodes/src/mytest_0/ThreadGetName.java b/JavaMultiThreadingCodes/src/mytest_0/ThreadGetName.java
@@ -0,0 +1,47 @@
+package mytest_0;
+
+/**
+ * @author liwen.
+ * @date 2016/7/20 17:30.
+ */
+public class ThreadGetName extends  Thread{
+
+    TestThread testThread;
+
+    public ThreadGetName(TestThread test) {
+        super("mytest222");
+        this.testThread=test;
+    }
+
+    public static void main(String[] args) {
+        TestThread test = new TestThread();
+        test.setName("mytest111");
+        test.start();
+        new ThreadGetName(test).start();
+    }
+
+    @Override
+    public void run() {
+        System.out.println("hello javaThread");
+    }
+
+}
+
+class TestThread extends Thread{
+
+    public String getResult(){
+        String name = Thread.currentThread().getName();
+        if(name.startsWith("mytest")){
+            String result = name + "---hello";
+            System.out.println(result);
+            return result;
+        } else{
+            return "";
+        }
+    }
+
+    @Override
+    public void run() {
+        getResult();
+    }
+}

Original file line number	Diff line number	Diff line change
`@@ -77,7 +77,7 @@ public void run() {`
`77`	`77`	`thread1.join(); //主线程等待子线程执行完后在执行下面的sysout`
`78`	`78`	`thread2.join();`
`79`	`79`	`} catch (InterruptedException ignored) {`
`80`		`-`
	`80`	`+ ignored.printStackTrace();`
`81`	`81`	`}`
`82`	`82`	`System.out.println("Count is: " + count); //用join保证保证前面两个线程已经执行完成`
`83`	`83`	`}`