Byte Stream vs Character Stream in Java

Question

I am working on I/O classes in Java. I understand that there are two important type of streams: byte stream and character stream. But... I have tried to read and write text file with byte stream and it worked. Here is the code:

    File klasor = new File("C:\\Java");
    if(!klasor.exists()) klasor.mkdirs();

    File kaynakDosya = new File("C:\\Java\\kaynak.txt");
    if(!kaynakDosya.exists()) kaynakDosya.createNewFile();

    File hedefDosya = new File("C:\\Java\\hedef.txt");
    if(!hedefDosya.exists()) hedefDosya.createNewFile();

    FileInputStream kaynak = new FileInputStream(kaynakDosya);
    FileOutputStream hedef = new FileOutputStream(hedefDosya);

    int c;
    while((c = kaynak.read()) != -1) {
        hedef.write(c);
    }

    if(kaynak != null) {
        kaynak.close();
    }

    if(hedef != null) {
        hedef.close();
    }

And then I did the same with character stream:

    File klasor = new File("C:\\Java");
    if(!klasor.exists()) klasor.mkdirs();

    File kaynakDosya = new File("C:\\Java\\kaynak.txt");
    if(!kaynakDosya.exists()) kaynakDosya.createNewFile();

    File hedefDosya = new File("C:\\Java\\hedef.txt");
    if(!hedefDosya.exists()) hedefDosya.createNewFile();

    FileReader kaynak = new FileReader(kaynakDosya);
    FileWriter hedef = new FileWriter(hedefDosya);

    int c;
    while((c = kaynak.read()) != -1) {
        hedef.write(c);
    }

    if(kaynak != null) {
        kaynak.close();
    }

    if(hedef != null) {
        hedef.close();
    }

These two produced the same result. So, I want to know, why shouldn't I use byte stream here but character stream? (I have read some articles as well as related questions here on stackoverflow and they say so) I know that character stream will read it character by character, but what advantage does this give me? Or what problems could occur if I read characters using byte stream? I hope my question is clear. I would appreciate real-case examples.

Answer 1

java.io.FileInputStream javadoc states :

FileInputStream is meant for reading streams of raw bytes such as image data. For reading streams of characters, consider using FileReader.

java.io.FileOutputStream javadoc states something similar enough :

FileOutputStream is meant for writing streams of raw bytes such as image data. For writing streams of characters, consider using FileWriter.

One of main differences between FileInputStream/FileOutputStream and FileReader/FileWriter is that the first provides methods to manipulate bytes while the latter provides methods to manipulate characters.

In your example, as you copy a file content into another file, manipulating char or byte doesn't make a big difference.
In your case, a FileInputStream or a BufferedInputStream seems even more appropriate.

But if you use a stream to read/write characters from/into String instances, using FileReader/FileWriter eases really the things and make things clearer.
Besides, you could also wrap FileReader/FileWriter into a BufferedReader/BufferedWriter and benefit from efficient reading/writting of characters, arrays, and lines.

 BufferedWriter writer = new BufferedWriter(new FileWriter("myfile"));
 writer.append(oneString);
 writer.append(oneStringBuffer);
 writer.newLine();

 BufferedReader reader = new BufferedReader(new FileReader("myfile"));
 String currentLine = reader.readLine();