【问题标题】：Syntax error on eclipse [closed]eclipse上的语法错误[关闭]
【发布时间】：2014-01-20 22:39:20
【问题描述】：

我的代码中的X's 变红了，因为我有关闭}。他们对我来说都很好，IDE坚持认为我错了。我不确定为什么这是不正确的。有人可以指导我吗，谢谢！

错误发生在最后2个关闭}

1 错误：

Syntax error on token "}", { expected after this 
 token

2 错误：

Syntax error, insert "}" to complete 
 ClassBody

这是我的代码

public class BinaryTree { 
    // root node pointer. Will be null for an empty tree
    private Node root;

    /*
     -- Node --
     The binary tree is built using this nested node class.
     Each node stores on data element, and has left and right 
     sub-tree pointer which may be null.
     The node is a "dumb" nested class -- we just use it for storage; 
     */

    private static class Node {     // Node class
        Node left;
        Node right;
        int data;

        Node(int newData) {         // create Node
            left = null;
            right = null;
            data = newData;
        }
    }

    /*
     Creates an empty binary tree == null root pointer
     */

    public void BinaryTree() {
        root = null;
    }

    /*
     Returns true if the given target is in the binary tree
     */

    public boolean lookup(int data) {       // look up a number 
        return(lookup(root, data));         // use this to parse through a tree to search for element
    }

    /*
     recursive lookup -- given a node, recur
     down searching for the given data.
     */
    private boolean lookup(Node node, int data) {
        if (node == null) {
            return(false);
        }

        if (data == node.data) {
            return(true);
        }
        else if (data < node.data) {
            return(lookup(node.left, data));
        }
        else {
            return(lookup(node.right, data));
        }
    }

    public void insert(int data) {
        root = insert(root, data);
    }

    /*
     Recursive insert -- given a pointer, recur down 
     and insert the given data into the tree. Returns the new 
     node pointer (the standard way to communicate 
     a changed pointer back to the caller).
     */

    private Node insert(Node node, int data) {
        if (node == null) {
            node = new Node(data);
        }
        else {
            if (data <= node.data) {
                node.left = insert(node.left, data);
            }
            else {
                node.right = insert(node.right, data);
            }
        }
    }    // I get an error here    #1

    return (node);
}        // I also get an error here   #2

【问题讨论】：

return (node); 不在方法内。它可能应该高 2 行...
请不要再为这样一个微不足道的问题发布答案。我相信 OP 可以在一点点帮助下自己回答他的问题。
通常日食会获胜..

标签： java eclipse

【解决方案1】：

您在任何方法之外的类末尾返回，这是一个错误。

【讨论】：

【解决方案2】：

完整的工作代码

public class BinaryTree { 
    // root node pointer. Will be null for an empty tree
    private Node root;

    /*
     -- Node --
     The binary tree is built using this nested node class.
     Each node stores on data element, and has left and right 
     sub-tree pointer which may be null.
     The node is a "dumb" nested class -- we just use it for storage; 
     */

    private static class Node {     // Node class
        Node left;
        Node right;
        int data;

        Node(int newData) {         // create Node
            left = null;
            right = null;
            data = newData;
        }
    }

    /*
     Creates an empty binary tree == null root pointer
     */

    public void BinaryTree() {
        root = null;
    }

    /*
     Returns true if the given target is in the binary tree
     */

    public boolean lookup(int data) {       // look up a number 
        return(lookup(root, data));         // use this to parse through a tree to search for element
    }

    /*
     recursive lookup -- given a node, recur
     down searching for the given data.
     */
    private boolean lookup(Node node, int data) {
        if (node == null) {
            return(false);
        }

        if (data == node.data) {
            return(true);
        }
        else if (data < node.data) {
            return(lookup(node.left, data));
        }
        else {
            return(lookup(node.right, data));
        }
    }

    public void insert(int data) {
        root = insert(root, data);
    }

    /*
     Recursive insert -- given a pointer, recur down 
     and insert the given data into the tree. Returns the new 
     node pointer (the standard way to communicate 
     a changed pointer back to the caller).
     */

    private Node insert(Node node, int data) {
        if (node == null) {
            node = new Node(data);
        }
        else {
            if (data <= node.data) {
                node.left = insert(node.left, data);
            }
            else {
                node.right = insert(node.right, data);
            }
        }
        // I get an error here    #1

    return (node);
}      }  //

【讨论】：

【解决方案3】：

将插入更改为：

  private Node insert(Node node, int data) {
            if (node == null) {
                node = new Node(data);
            }
            else {
                if (data <= node.data) {
                    node.left = insert(node.left, data);
                   }
                else {
                    node.right = insert(node.right, data);
                     }
                 }
                 return (node);
        }

在 eclipse 中：按 Ctrl + a 然后 Ctrl+shift+f 格式化代码..你会很容易知道这样的错误......

【讨论】：

【解决方案4】：

错误是因为你有以下语句

return (node);

在你的 insert 方法之外

【讨论】：

【解决方案5】：

    private Node insert(Node node, int data) {
            if (node == null) {
                node = new Node(data);
            }
            else {
                if (data <= node.data) {
                    node.left = insert(node.left, data);
                }
                else {
                    node.right = insert(node.right, data);
                }
       -->      return (node);// I get an error here    #1
--->       }

你在外面写了return语句。我把它搬了进去。请更新。

【讨论】：