我使用读写从树中加载和保存文件。为什么当我将员工保存到记事本时是工作。但是我无法再次将其加载到节点中以在运行时显示它。有人可以帮助我吗？我的读取功能有问题吗？我不知道如何将数据从文件 txt 读取到树并在运行时加载它。
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 Testn");
char ch;
/* Perform tree operations */
do
{
System.out.println("nBinary Search Tree Operationsn");
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');
}
}
"我不知道如何将数据从文件 txt 读取到树并在运行时加载它。
所以您似乎只是试图将 BST 写入.txt文件，然后从该.txt文件中读取以构建 BST？
读取和写入方法必须相互一致(如何读取文件取决于写入.txt文件的格式(：
将 BST 写入.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
}
所以一个以格式编写的示例：
值
值
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);
}
}
然后，如果您想从该格式的文件中读取...
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
}
我希望这有所帮助。