Difference between PrintWriter and FileWriter class

Question

try{

    File file = new File("write.txt");
    FileWriter writer = new FileWriter(file);

    PrintWriter printWriter = new PrintWriter(writer);
    printWriter.println("pqr");
    printWriter.println("jkl");
    printWriter.close();

    PrintWriter printWriter = new PrintWriter(file);
    printWriter.println("abc");
    printWriter.println("xyz");
    printWriter.close();
}

I don't understand what is difference bet'n these two way. In which scenario i should use printWriter and fileWriter.

Answer 1

From the source what PrintWriter does when you pass a File is to open it in a buffered way

public PrintWriter(File file) throws FileNotFoundException {
    this(new BufferedWriter(new OutputStreamWriter(new FileOutputStream(file))),
         false);
}

if you pass it a FileWriter, it will open it, without buffering

public FileWriter(File file) throws IOException {
    super(new FileOutputStream(file));
}

This means that the first example can be slightly more efficient. However I would use the File without the FileWriter because to me it is simpler.

Answer 2

Although both of these internally uses a FileOutputStream , the main difference is that PrintWriter offers some additional methods for formatting like println and printf.

code snippets:

public PrintWriter(File file) throws FileNotFoundException {
     this(new BufferedWriter(new OutputStreamWriter(new FileOutputStream(file))),
     false);
}


public FileWriter(File file) throws IOException {
       super(new FileOutputStream(file));
}

Major Differences :

1. FileWriter throws IOException in case of any IO failure.
2. None of the PrintWriter methods throws IOException, instead they set a boolean flag which can be obtained using checkError().
3. PrintWriter comes with an option of autoflush while creation(default is without autoflush) which will flush after every byte of data is written. In case of FileWriter, caller has to take care of invoking flush.