java学习日记20230412-LinkedList

LinkedList全面说明

• LinkedList底层实现了双想链表和双端队列的特点；
• 可以添加人意元素，可重复，包括null
• 线程不安全，没有实现同步
• LinkedList维护了first和last两个属性，分别指向首节点和尾节点
• 每个节点Node对象，里面又维护了prev，next，item三个属性，其中通过prev指向前一个，通过next指向后一个节点，最终实现双向链表
• LinkedList元素的添加和删除，不是通过数组完成的，相对来说效率较高
• Node示例

  
  public class LinkedListExercise {
      public static void main(String[] args) {
          LinkedList<Object> objects = new LinkedList<>();
  
          Node jack = new Node("jack");
          Node tom = new Node("tom");
          Node laohan = new Node("laohan");
          Node cs = new Node("cs");
  
          jack.next = tom;
          tom.next = cs;
          laohan.pre = cs;
          cs.next=laohan;
          cs.pre=tom;
          tom.pre = jack;
          Node first = jack;
          Node last = laohan;
          while(true){
              if(first == null){break;}
              System.out.println(first);
              first = first.next;
          }
      }
  }
  
  //模拟node节点
  class Node{
      public Object item;
      public Node next;
      public Node pre;
  
      public Node(Object item) {
          this.item = item;;
      }
  
      @Override
      public String toString() {
          return "Node{" +
                  "item=" + item +
                  '}';
      }
  }

• public class LinkedListCRUD {
      public static void main(String[] args) {
          //初始化
          LinkedList<Object> objects = new LinkedList<>();
          objects.add(1);
          objects.add(2);
          objects.add(3);
          System.out.println(objects);
  
          objects.remove();
          System.out.println(objects);
          //修改
          objects.set(1,4);
          System.out.println(objects);
          //获取
          System.out.println(objects.get(1));
          //迭代器循环
          Iterator iterator =objects.listIterator();
  
          while(iterator.hasNext()){
              System.out.println(iterator.next());
          }
          //增强for循环
          for (Object o :objects) {
              System.out.println(o);
          }
  
      }
  }