What wrong with my code?

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Java

i am creating a program that will create a text file and write hello world
if the program is run twice on the same day the textfile should contain 2 hello world and if it is run on the same day but different month it should erase the existing written text and write another hello world;

What I have tried:

Calendar calendar = Calendar.getInstance();
    Date date = new Date();
    calendar.setTime(date);
    int month = calendar.get(Calendar.DAY_OF_MONTH);
   
   File myFile = new File("log_"+month+".txt");
    if(!myFile.exists())
    {
        myFile.createNewFile();
        PrintWriter out = new PrintWriter(myFile);
        out.write("Hello World"+System.lineSeparator());
        out.close();
        System.out.print("First Creation");
        return;
    }

     if(myFile.exists())
   {
      
        Path p = Paths.get(myFile.toString());
     BasicFileAttributes attr = Files.readAttributes(p, BasicFileAttributes.class);
  
     FileTime creation = attr.creationTime();
     DateFormat df = new SimpleDateFormat("MM:dd");
     String x = df.format(creation.toMillis());
     String y = new SimpleDateFormat("MM:dd").format(calendar.getTime());
     attr = null;
     if((x).equals(y))
       {
         FileWriter fw = new FileWriter(myFile.getAbsoluteFile(),true);
   BufferedWriter output = new BufferedWriter(fw);
         output.write("Hello World" +System.lineSeparator());
         output.close();
         System.out.print("Existing");
         df = null;
       }
      else {
      
           myFile.delete();
            myFile.createNewFile();
    PrintWriter out = new PrintWriter(myFile);
    out.write("Hello World"+System.lineSeparator());
    out.close();
           System.out.print(x+y);
          
      }
   }