java: how to convert a file to utf8

Question

i have a file that have some non-utf8 caracters (like "ISO-8859-1"), and so i want to convert that file (or read) to UTF8 encoding, how i can do it?

The code it's like this:

File file = new File("some_file_with_non_utf8_characters.txt");

/* some code to convert the file to an utf8 file */

...

edit: Put an encoding example

Answer 1

The following code converts a file from srcEncoding to tgtEncoding:

public static void transform(File source, String srcEncoding, File target, String tgtEncoding) throws IOException {
    BufferedReader br = null;
    BufferedWriter bw = null;
    try{
        br = new BufferedReader(new InputStreamReader(new FileInputStream(source),srcEncoding));
        bw = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(target), tgtEncoding));
        char[] buffer = new char[16384];
        int read;
        while ((read = br.read(buffer)) != -1)
            bw.write(buffer, 0, read);
    } finally {
        try {
            if (br != null)
                br.close();
        } finally {
            if (bw != null)
                bw.close();
        }
    }
}

--EDIT--

Using Try-with-resources (Java 7):

public static void transform(File source, String srcEncoding, File target, String tgtEncoding) throws IOException {
    try (
      BufferedReader br = new BufferedReader(new InputStreamReader(new FileInputStream(source), srcEncoding));
      BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(target), tgtEncoding)); ) {
          char[] buffer = new char[16384];
          int read;
          while ((read = br.read(buffer)) != -1)
              bw.write(buffer, 0, read);
    } 
}