Open your file in append mode like this
FileWriter(String fileName, boolean append)
when you want to make an object of class FileWrite
in constructor.
File file = new File("C:\\Users\\Izak\\Documents\\NetBeansProjects\\addNewLinetoTxtFile\\src\\addnewlinetotxtfile\\a.txt");
try (Writer newLine = new BufferedWriter(new FileWriter(file, true));) {
newLine.write("New Line!");
newLine.write(System.getProperty( "line.separator" ));
} catch (IOException e) {
}
Note:
"line.separator" is a Sequence used by operating system to separate lines
in text files
source:
http://docs.oracle.com/javase/tutorial/essential/environment/sysprop.html