完善了SimpleLinkedList的add方法

byhieg · byhieg · commit cc5b79b97561 · 2017-02-15T13:43:39.000+08:00
diff --git a/src/main/java/cn/byhieg/collectiontutorial/listtutorial/SimpleLinkedList.java b/src/main/java/cn/byhieg/collectiontutorial/listtutorial/SimpleLinkedList.java
@@ -1,5 +1,7 @@
 package cn.byhieg.collectiontutorial.listtutorial;
 
+import apple.laf.JRSUIFocus;
+
 /**
  * Created by byhieg on 17/2/15.
  * Mail to byhieg@gmail.com
@@ -13,6 +15,69 @@ public class SimpleLinkedList<E> {
     private Node<E> last;
 
 
+
+    public boolean add(E element) {
+       addAtLast(element);
+        return true;
+    }
+
+    private void addAtLast(E element){
+        Node<E> l = last;
+        Node<E> node = new Node<E>(element,null,l);
+        last = node;
+        if (l == null) {
+            first = node;
+        }else {
+            l.next = node;
+        }
+        size++;
+    }
+
+    public void add(int index, E element) {
+        checkRangeForAdd(index);
+        if (index == size){
+            addAtLast(element);
+        }else{
+            Node<E> l = node(index);
+            addBeforeNode(element,l);
+        }
+    }
+
+    private void addBeforeNode(E element,Node<E> specifiedNode){
+        Node<E> preNode = specifiedNode.prev;
+        Node<E> newNode = new Node<>(element, specifiedNode,preNode);
+        if (preNode == null) {
+            first.next = newNode;
+        }else {
+            preNode.next = newNode;
+        }
+        specifiedNode.prev = newNode;
+        size ++;
+    }
+
+
+    private Node<E> node(int index){
+        if (index < (size<<1)){
+            Node<E> cursor  = first;
+            for (int i = 0 ; i < index ; i++) {
+                cursor = cursor.next;
+            }
+            return cursor;
+        }else {
+            Node<E> cursor = last;
+            for (int i = size -1 ; i > index ; i--) {
+                cursor = cursor.prev;
+            }
+            return cursor;
+        }
+    }
+
+    private void checkRangeForAdd(int index){
+        if (index > size || index < 0) {
+            throw new IndexOutOfBoundsException("指定的index超过界限");
+        }
+    }
+
     private static class Node<E>{
         E item;
         Node<E> next;
