如何从Java中的文件二叉搜索树加载数据？

Question

我使用读取和写入从树中加载和保存文件。为什么当我将员工保存到记事本是工作。但是当我运行时，我无法再将其加载到节点中以显示它。有谁能够帮助我？我的阅读功能有问题吗？我不知道如何从文件txt读取数据到树中，并在我运行时加载它。

import java.io.BufferedOutputStream; 
import java.io.BufferedWriter; 
import java.io.EOFException; 
import java.io.FileInputStream; 
import java.io.FileOutputStream; 
import java.io.FileWriter; 
import java.io.IOException; 
import java.io.ObjectInputStream; 
import java.io.ObjectOutputStream; 
import java.io.PrintWriter; 
import java.io.Serializable; 

import java.util.Scanner; 
import java.util.StringTokenizer; 
import java.util.Vector; 

class Employee implements Comparable<Employee>, Serializable { 
    private static final long serialVersionUID = 1L; 

     private int ID; 
     private String name; 
     String address; 
     public Employee getName; 

     Employee(int emp_ID, String emp_name, String emp_address){ 
      ID = emp_ID; 
      name = emp_name; 
      address = emp_address; 
     } 
     public void print(){ 
      System.out.println(ID); 
      System.out.println(name); 
      System.out.println(address); 
     } 
     @Override 
     public String toString() { 
      return ID + "-" + name + "-" + address; 
     } 

     public int getID () 
     { 
      return ID; 
     } 

     public void setID (int emp_ID) 
     { 
      ID = emp_ID;   
     } 

     public String getName () 
     { 
      return name; 
     } 

     public void setName (String emp_Name) 
     { 
      name = emp_Name;   
     } 

     @Override 
     public int compareTo(Employee o) {  
      return 0; 
     } 

     public void input() { 
      System.out.print("Please input an Employee \n"); 
      Scanner myScanner = new Scanner(System.in); 
      System.out.println("Please input an Employee ID"); 
      ID = myScanner.nextInt(); 
      myScanner.nextLine(); 
      System.out.println("Please input an Employee Name"); 
      name = myScanner.nextLine(); 
      System.out.println("Please input an Employee Address"); 
      address = myScanner.nextLine(); 
      } 
    } 
} 

/* Class BST */ 
class BST 
{ 
    private Node root; 

    /* Constructor */ 
    public BST() 
    { 
     root = null; 
    } 
    /* Function to check if tree is empty */ 
    public boolean isEmpty() 
    { 
     return root == null; 
    } 
    /* Functions to insert data */ 
    public void insert(Employee emp) 
    { 
     root = insert(root, emp); 
    } 
    /* Function to insert data recursively */ 
    private Node insert(Node node, Employee emp) 
    { 
     if (node == null) 
      node = new Node(emp); 
     else 
     { 
      if (emp.getID() <= node.getID()) 
       node.left = insert(node.left, emp); 
      else 
       node.right = insert(node.right, emp); 
     } 
     return node; 
    } 
    /* Functions to delete data */ 

    /* Functions to count number of nodes */ 

    /* Functions to search for an element */ 

    /* Function to search for an element recursively */ 

    /* Function for inorder traversal */ 
    public void inorder() 
    { 
     inorder(root); 
    } 
    private void inorder(Node r) 
    { 
     if (r != null) 
     { 
      inorder(r.getLeft()); 
      System.out.print(r.getData() +" "); 
      inorder(r.getRight()); 
     } 
    } 
    /* Function for preorder traversal */ 
    public void preorder() 
    { 
     preorder(root); 
    } 

    private void preorder(Node r) 
    { 
     if (r != null) 
     { 
      System.out.print(r.getData() +" "); 
      preorder(r.getLeft());    
      preorder(r.getRight()); 
     } 
    } 
    /* Function for postorder traversal */ 
    public void postorder() 
    { 
     postorder(root); 
    } 

    private void postorder(Node r) 
    { 
     if (r != null) 
     { 
      postorder(r.getLeft());    
      postorder(r.getRight()); 
      System.out.print(r.getData() +" "); 
     } 
    } 

    public static int Read() { 
     int count=0; 
     try{ 
      Vector<Employee> vector = new Vector<Employee>(); 
      FileInputStream saveFile = new FileInputStream("D:/info.txt"); 
      ObjectInputStream save; 
      try{ 
       for(;;){ 
        save = new ObjectInputStream(saveFile); 
        Employee emp = (Employee) save.readObject(); 
        vector.add(emp); 
        count++; 
       } 
      }catch(EOFException e){ 
       //e.printStackTrace(); 
      } 
      saveFile.close(); 

     }catch(Exception exc){ 
      exc.printStackTrace(); 
     } 
     return count; 
    } 

    public void Write(Employee mm) { 
     try 
      { 
      FileOutputStream fileOut = new FileOutputStream("D:/info.txt",true); 
      ObjectOutputStream out = new ObjectOutputStream(new BufferedOutputStream(fileOut)); 

      out.writeObject(mm);    
      out.close(); 
      fileOut.close(); 
      System.out.println("Serialized data is saved in info.ser"); 
      }catch(IOException i) 
      { 
       //i.printStackTrace(); 
      } 
    } 
} 

/* Class BinarySearchTree */ 
public class Binary 
{ 
    public static void main(String[] args) 
    {  
     Employee emp = null; 

     int ID = 0; 

     String name = null; 
     int uID = 0; 
     String address = null; 
     Scanner scan = new Scanner(System.in); 

     /* Creating object of BST */ 
     BST bst = new BST(); 

     System.out.println("Binary Search Tree Test\n");   
     char ch; 
     /* Perform tree operations */ 
     do  
     { 
      System.out.println("\nBinary Search Tree Operations\n"); 
      System.out.println("1. insert "); 
      int choice = scan.nextInt();    
      switch (choice) 
      { 
      case 1 : 
       System.out.print("Please input an Employee \n"); 

       System.out.println("Please input an Employee ID"); 
       ID = scan.nextInt(); 
       scan.nextLine(); 
       System.out.println("Please input an Employee Name"); 
       name = scan.nextLine(); 
       System.out.println("Please input an Employee Address"); 
       address = scan.nextLine(); 
       emp = new Employee(ID,name,address); 
       bst.insert(emp); 
       bst.Write(emp); 
       break;       
      default : 
       System.out.println("Wrong Entry \n "); 
       break; 
      } 
      /* Display tree */ 
      System.out.print("\nPost order : "); 
      bst.postorder(); 
      System.out.print("\nPre order : "); 
      bst.preorder(); 
      System.out.print("\nIn order : "); 
      bst.inorder(); 

      System.out.println("\nDo you want to continue (Type y or n) \n"); 
      ch = scan.next().charAt(0);       
     } while (ch == 'Y'|| ch == 'y');    
    }  
} 

Answer 1

“我不知道如何从文件中读取TXT数据树并加载它，当我跑。”

soo似乎你只是简单地将BST写入一个.txt文件，然后从该.txt文件中读取以构建BST？

的读取和写入方法必须互相同意（你如何从文件中读取取决于其.txt文件的撰写格式）：

写的BST到.txt文件的示例：

public static void main() { 
    BST tree = //constructed BST 
    PrintStream output = new PrintStream(new File(//name of file to write to)); 
    tree.write(output); // to write the tree to a file 
    FileInputStream input = new FileInputStream(//file name goes here); 
    tree.read(input); // to construct the tree from a file 
} 

所以在书写格式的例子：
价值
价值
等等

public void write(PrintStream output) { 
     write(overallRoot, "", output); 
    } 

    private void write(TreeNode root, String code, PrintStream output) { 
     if(root != null) { 
      if(root.left == null && root.right == null) { 
       output.println(root.data + "\n"); 
      } 
      // recursive-case 
      write(root.left, output); 
      write(root.right, output); 
     } 
    } 

，如果你想从与该格式文件阅读，然后...

public void read(FileInputStream input) { 
    TreeNode node = new TreeNode(input.nextLine()); //read from file line by line 
    tree.insert(node); // use a BST insert method to build the tree node by node 
} 

我希望这有助于。