queue.removeAll(list); System.out.println("Queue:"+queue); } } 输出: Exception in thread "main" java.lang.NullPointerException at java.util.concurrent.ConcurrentLinkedQueue.checkNotNull(ConcurrentLinkedQueue.java:920) at java.util.concurrent.ConcurrentLinkedQueue.offer(ConcurrentLinkedQueue.java:327)...
queue.retainAll(list); System.out.println("Queue = "+queue); } } 輸出: Exception in thread "main" java.lang.NullPointerException at java.util.TreeMap.put(TreeMap.java:563) at java.util.TreeSet.add(TreeSet.java:255) at com.javaTpoint.ConcurrentLinkedQueueRetainAllExample3.main(Concurrent...