I'm learning how to read from and write to programs right now, and just spent more time than I would like to admit trying to figure out why my code wouldn't work. I forget to include FileWriter.close() at the end of my function. This has happened many times since the start of this section of learning java.

Why is it so important? Shouldn't a FileWriter "close" when the program ends? Like the FileWriter literally won't properly write to a file unless I include the call to this method, even when including a seemingly more important method call (i.e. FileWriter.write("foobar"))

if it makes any difference, this is the class I'm working in: https://pastebin.com/73hrSjtP

So I am confused with the flush() method of the PrintWriter class. According to all documentation descriptions, it 'flushes' the stream, whatever that means. Luckily I got a better explanation somewhere else, but even then it didn't explain how I'd seen it function. GeeksforGeeks said " it means to clear the stream of any element that may be or maybe not inside the stream". Ok, so I assume that just means it empties the stream, yes?

No, that is not what it does. The given code from the GeeksforGeeks website (found here) is as follows:

// Java program to demonstrate 
// PrintWriter flush() method 
  
import java.io.*; 
  
class GFG { 
    public static void main(String[] args) 
    { 
  
        // The string to be written in the Writer 
        String str = "GeeksForGeeks"; 
  
        try { 
  
            // Create a PrintWriter instance 
            PrintWriter writer 
                = new PrintWriter(System.out); 
  
            // Write the above string to this writer 
            // This will put the string in the stream 
            // till it is printed on the console 
            writer.write(str); 
  
            // Now clear the stream 
            // using flush() method 
            writer.flush(); 
        } 
        catch (Exception e) { 
            System.out.println(e); 
        } 
    } 
} 

With output as follows:

GeeksForGeeks

Simple enough right? Well if you remove line 26 of the code above (writer.flush()) then you get no output. So that means that when you flush the input stream, it actually goes somewhere, it doesn't just get erased. So why isn't that put into the documentation and explanation?

I am upset about this whole thing and I'm annoyed that the official documentation doesn't elaborate more on what 'flush' means in the context of the method, class, etc. But aside from me being upset, I would like someone to either explain whats going on here or to link me to some documentation that actually gets it right.