Java 文件是否存在取决于时间的推移

我试图通过javacode传递特定的时间戳来为文件夹中存在的新文件编码，但我没有得到它..你能帮我吗

String filePath = System.getProperty("user.dir");
    //create a new file with Time Stamp
    File file = new File(filePath + "\\" + filename+GetCurrentTimeStamp().replace(":","_").replace(".","_")+".txt");

    try {
        if (!file.exists()) {
            file.createNewFile();
            System.out.println("File is created; file name is " + file.getName());
        } else {
            System.out.println("File already exist");
        }
    } catch (IOException e) {
        e.printStackTrace();
    }
}
    // Get current system time
public static String GetCurrentTimeStamp() {
    SimpleDateFormat sdfDate = new SimpleDateFormat(
            "yyyy-MM-dd HH:mm:ss.SSS");// dd/MM/yyyy
    Date now = new Date();
    String strDate = sdfDate.format(now);
    return strDate;
}
// Get Current Host Name
public static String GetCurrentTestHostName() throws UnknownHostException {
    InetAddress localMachine = InetAddress.getLocalHost();
    String hostName = localMachine.getHostName();
    return hostName;
}

// Get Current User Name
public static String GetCurrentTestUserName() {
    return System.getProperty("user.name");

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我不知道你想描述什么。此外，请详细说明“我不明白”的含义。实际问题是什么？

package com.test;

import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Date;

public class trst {

    public static void main(String[] args) throws IOException {
        // TODO Auto-generated method stub
        boolean b = false;
        File file, file1;
        Date today = new Date();
                SimpleDateFormat ft = new SimpleDateFormat ("MMddyyyyhhmmss");
                String folder_name="backup_"+ft.format(today);
            file = new File("./"+folder_name);  
        if (!file.exists()) 
        {
            b = file.mkdirs();
        }
        file1 = new File(file+"/"+"Test");
        FileWriter fileWriter = new FileWriter(file1);
        fileWriter.write("abc");
        fileWriter.flush();
        fileWriter.close();
        if (b)
        System.out.println("Backup has been created.");
        else
        System.out.println("Failed to create backup.");
    }

}