java - 按字母顺序将节点插入链表

Question

我目前正在编写一个将字符串插入链表的程序，但是当它插入字符串时，它会按字母顺序对它们进行排序(使用 compareTo 方法)。我正在尝试涵盖所有可能的边界，并且目前停留在如何插入一个新节点(如果它位于列表的开头)(因此，变量 previous 为空)。这是我到目前为止所拥有的:

public class LinkedList{
private Node root;
private Node tail;

public void add(String data){
    Node current = root;
    Node previous = null;
    Node newNode = new Node(data);
    if(root == null){
        root = newNode;
        tail = root;
        newNode.next = null;
        return;
    }
    for( ; current != null; previous = current, current = current.next){
        if(newNode.data.compareTo(current.data)<= 0){
            break;
        }
    }
    if(previous != null){
        newNode.next = current;
        previous.next = newNode;
        if(current == null) { 
            tail = newNode;
        }
    } else{ 
        // if Previous IS null
        previous = newNode;        //The code that does not work as expected
        newNode.next = current; 

    }
}

public static final void main(String[] args){
    LinkedList list = new LinkedList();
    // for(int i = 0; i < 10; i++){
    //     list.add("Item");
    // }
    list.add("Item1");
    list.add("Item2");
    list.add("Item4");
    System.out.println(list.toString());
    list.add("Item3");
    System.out.println(list.toString());
    list.add("Item3");
    System.out.println(list.toString());
    list.add("Item0");
    System.out.println(list.toString());


}

Answer 1

你只需要插入节点:

  else{ 
      // if Previous IS null
      newNode.next = root;
      root=newNode;
 }