fix code

hutool-cron/src/main/java/cn/hutool/cron/listener/TaskListenerManager.java

@@ -1,12 +1,12 @@
 package cn.hutool.cron.listener;
 
+import cn.hutool.cron.TaskExecutor;
+import cn.hutool.log.StaticLog;
+
 import java.io.Serializable;
 import java.util.ArrayList;
 import java.util.List;
 
-import cn.hutool.cron.TaskExecutor;
-import cn.hutool.log.StaticLog;
-
 /**
  * 监听调度器，统一管理监听
  * @author Looly
@@ -49,9 +49,9 @@ public class TaskListenerManager implements Serializable {
 		synchronized (listeners) {
 			int size = listeners.size();
 			TaskListener listener;
-			for (int i = 0; i < size; i++) {
-				listener = listeners.get(i);
-				if(null != listener){
+			for (TaskListener taskListener : listeners) {
+				listener = taskListener;
+				if (null != listener) {
 					listener.onStart(executor);
 				}
 			}
@@ -65,8 +65,7 @@ public class TaskListenerManager implements Serializable {
 	public void notifyTaskSucceeded(TaskExecutor executor) {
 		synchronized (listeners) {
 			int size = listeners.size();
-			for (int i = 0; i < size; i++) {
-				TaskListener listenerl = listeners.get(i);
+			for (TaskListener listenerl : listeners) {
 				listenerl.onSucceeded(executor);
 			}
 		}
@@ -82,8 +81,7 @@ public class TaskListenerManager implements Serializable {
 		synchronized (listeners) {
 			int size = listeners.size();
 			if(size > 0){
-				for (int i = 0; i < size; i++) {
-					TaskListener listenerl = listeners.get(i);
+				for (TaskListener listenerl : listeners) {
 					listenerl.onFailed(executor, exception);
 				}
 			}else{