Update SinglyLinkedList.java

src/main/java/com/nbee/solution/practice/SinglyLinkedList.java

@@ -1,12 +1,52 @@
 package com.nbee.solution.practice;
 
+import java.util.Iterator;
 import java.util.function.Consumer;
 
 /**
  * 链表类
  */
-public class SinglyLinkedList {
+public class SinglyLinkedList implements Iterable<Integer> {
     private Node head;
+
+    @Override
+    public Iterator<Integer> iterator() {
+        return new Iterator<Integer>() {
+            Node p = head;
+
+            @Override
+            public boolean hasNext() {
+                return p != null;
+            }
+
+            @Override
+            public Integer next() {
+                int value = p.value;
+                p = p.next;
+                return value;
+            }
+        };
+    }
+
+    private Node findLast() {
+        if (head == null) {
+            return null;
+        }
+        Node p;
+        for (p = head; p != null; p = p.next) {
+        }
+        return p;
+    }
+
+    public void addLast(int value) {
+        Node last = findLast();
+        if (last == null){
+            addFirst(value);
+            return;
+        }
+        last.next = new Node(value, null);
+    }
+
     private static class Node {
         int value;
         Node next;
@@ -16,12 +56,14 @@ public class SinglyLinkedList {
             this.next = next;
         }
     }
+
     public void addFirst(int value) {
         //链表为空
 //        head = new Node(value,null);
         //链表非空，包含了链表为空的情况
         head = new Node(value, head);
     }
+
     public void loop(Consumer<Integer> consumer) {
         Node p = head;
         while (p != null) {