多线程环境下，保证仅且只执行一次

Author: xhkyyy

java87/src/main/java/multi_threads/Test.java

@@ -27,8 +27,12 @@ public static void main(String[] args) {
             }
         }
 
-        System.out.println();
-        System.out.println("count: " + RWThread.count);
+        if (RWThread.count.get() != 1) {
+            throw new IllegalStateException();
+        } else {
+            System.out.println();
+            System.out.println("count: " + RWThread.count);
+        }
 
 
     }

java87/src/main/java/multi_threads/atomic_start_once/RWThread.java

@@ -13,6 +13,8 @@ public class RWThread extends Thread {
     @Override
     public void run() {
 
+        System.out.println("Thread ID: " + Thread.currentThread().getId());
+
         // 多线程环境下，保证仅且只执行一次
         if (!ab.compareAndSet(false, true)) {
             return;