Filewriter will not append text to newly created file

I'm fairly new to Java. I was trying to add "List:" to the beginning of a new text file if it doesn't exist. Instead, the text file is blank, with the input below a line of blank space. 

File hi = new File("hi.txt");
try{
  if(!hi.exists()){
    System.out.printf("\nCreating 'hi.txt'."); 
    hi.createNewFile();
    String hello = "List:";
    new FileWriter(hi).append(hello);
  }
  else{
    System.out.printf("\nWriting to 'hi.txt'");
  }
  FileWriter writeHere = new FileWriter(hi, true);
  String uling = "hi";
  writeHere.append(uling);
  writeHere.close();
}
//error catching
catch(IOException e){
  System.out.printf("\nError. Check the file 'hi.txt'.");}
Jon Skeet
people
quotationmark

The problem is with this line:

new FileWriter(hi).append(hello);

You're not closing the writer, which means:

  • The file handle is potentially still open, which could cause problems when you try to write to it
  • You're not flushing the writer, so the input may get lost

You should also get in the habit of using try-with-resources to acquire and then automatically close the writer, even if an exception occurs.

Personally, I'd change the structure of your code somewhat so you only open the file once:

File hi = new File("hi.txt");
boolean newFile = !hi.exists();
System.out.printf("%n%s 'hi.txt'.", newFile ? "Creating" : "Writing to");
try (Writer writer = new FileWriter(hi, true)) {
    // Note: if you've already got a string, you might as well use write...
    if (newFile) {
        writer.write("List:");
    }
    writer.write(uling);
}
catch(IOException e) {
  System.out.printf("\nError. Check the file 'hi.txt'.");
}

people

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