Java中如何通过构造函数连接两个StringNode节点？

Hey there, let's work through this problem step by step to get your nodes connected properly!

1. Why you're seeing the "Edgelist(StringNode, StringNode) is undefined" error #

The core issue here is that you're trying to create an EdgeList instance using new EdgeList(node1, node2), but your EdgeList class doesn't have a constructor that accepts two StringNode parameters. Java automatically generates a no-argument constructor for classes unless you define your own, so the compiler can't find the constructor you're trying to use.

2. Fixing the constructor error + fixing your node connection logic #

Your original insert method also has a critical flaw: it uses recursive logic with no termination condition, which would cause a StackOverflowError if it ran. Let's fix both issues with two clear options:

Option 1: Add a parameterized constructor to handle connection on instantiation #

If you want to connect the nodes as soon as you create an EdgeList object, add a constructor that takes the two nodes and handles the connection:

package Linear;
public class EdgeList {
    // New constructor that connects the two nodes
    public EdgeList(StringNode firstNode, StringNode secondNode) {
        // Connect firstNode to secondNode (adjust this logic if you need reverse connection)
        firstNode.next = secondNode;
    }

    // Optional: If you still need an insert method, here's a corrected version
    public StringNode insertToEnd(StringNode head, StringNode newNode) {
        if (head == null) {
            return newNode;
        }
        StringNode current = head;
        // Traverse to the end of the list
        while (current.next != null) {
            current = current.next;
        }
        current.next = newNode;
        return head;
    }
}

Then call it like this in your main method:

public static void main(String[] args) {
    StringNode everest = new StringNode("Everest", null);
    StringNode kilimanjaro = new StringNode("Kilimanjaro", null);
    
    // Now this works because we defined the parameterized constructor
    EdgeList edgeList = new EdgeList(everest, kilimanjaro);
    
    // Test the connection
    System.out.println(everest.next); // Outputs "Kilimanjaro"
}

Option 2: Use the default no-arg constructor + a dedicated connection method #

If you prefer to separate instantiation and connection logic, keep the default constructor and create a clear method to link the nodes:

package Linear;
public class EdgeList {
    // Default no-arg constructor (automatically provided, but we can write it explicitly)
    public EdgeList() {}

    // Simple method to connect two nodes
    public void connectNodes(StringNode sourceNode, StringNode targetNode) {
        sourceNode.next = targetNode;
    }
}

Call it like this:

public static void main(String[] args) {
    StringNode everest = new StringNode("Everest", null);
    StringNode kilimanjaro = new StringNode("Kilimanjaro", null);
    
    // Use default constructor
    EdgeList edgeList = new EdgeList();
    // Call the connection method
    edgeList.connectNodes(everest, kilimanjaro);
    
    // Verify the link
    System.out.println(everest.next); // Outputs "Kilimanjaro"
}

3. Why your original insert method was broken #

Your original insert method used secondNode.next = insert(firstNode, secondNode.next); which is an infinite recursive call—there's no condition to stop the recursion (like checking if secondNode.next is null). This would crash your program with a StackOverflowError as soon as it ran, so replacing that logic with a straightforward connection or a properly bounded traversal is essential.

内容的提问来源于stack exchange，提问作者CodingIsHardMan