update main

2.javaThreadDemo/src/Main.java

@@ -1,3 +1,5 @@
+import java.util.concurrent.*;
+
 public class Main {
 
     public static void main(String[] args) {
@@ -6,3 +8,15 @@ public class Main {
         System.out.println("当前线程id为：" + Thread.currentThread().getId());
     }
 }
+
+class Item implements Delayed {
+    @Override
+    public long getDelay(TimeUnit unit) {
+        return 0;
+    }
+
+    @Override
+    public int compareTo(Delayed o) {
+        return 0;
+    }
+}