my Java program doesn't write anything in my .csv file, even though there is no "file not found" error

My code is :

	FileWriter writer = new FileWriter("fisiere/audit.csv", true);
	DateTimeFormatter dtf = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm");
	LocalDateTime now = LocalDateTime.now();
	writer.append(dtf.format(now));
	writer.append(",");
	writer.append("insereazaTabelCandidatiLinie");
	writer.append(",");
	writer.append(Thread.currentThread().getName());
	writer.append("\n");

I want to open the .csv file and write in it the name of the called method and time and date of calling, this code works in main and it writes what I need in the file, but when I use the same code in my method it doesn't write anything. The method is called, I checked by printing to the screen a short message right before executing the lines above, the message has been displayed to the screen.

Data may not be written to disk as soon as it is appended to the FileWriter. One reason for this is writing to disk can be a relatively slow/expensive operation. To address this, incoming data may be written to a buffer in memory instead and 'flushed' to disk at a later time manually by calling 'flush' or 'close' or if the memory buffer becomes full. The easiest way to ensure data is flushed at the end of the program is by scoping the lifespan of the FileWriter using a 'try-with-resources' block.

public static void main(String[] args) throws Exception
	{
		LocalDateTime now = LocalDateTime.now();
		DateTimeFormatter dtf = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm");
		try(FileWriter writer = new FileWriter("fisiere/audit.csv", true))
		{
			writer.append(dtf.format(now));
			writer.append(",");
			writer.append("insereazaTabelCandidatiLinie");
			writer.append(",");
			writer.append(Thread.currentThread().getName());
			writer.append("\n");
		}
	}

This will automatically call 'close' which will cause data to be flushed when the try block completes.

Edit - High-level when to flush

When to flush data will be largely context specific. In general, the maximum write frequency should be every time a complete message has been written to the buffer. Ex: in the above, don't call flush until new line because it may lead to a file reader seeing incomplete data (the thread name may be missing).

Depending on the expected write throughput, the maximum frequency may use system resources less efficiently than desired. In this case, batching messages in memory before flushing or waiting some time interval between flushing may be preferred.

Note the trade-off between the file more accurately reflecting the real-time state of the process vs more work being done by the process.