Read/Write Files Related in Java

Reading:

java.io.InputStream
  - java.io.FileInputStream
  - java.io.FilterInputStream
    - java.io.BufferedInputStream

When to use: Deal with charset problem (InputStream is byte-based, FileInputStream makes it char-based)

Example:

InputStreamReader isr = new InputStreamReader(
    new FileInputStream("test.txt"),"utf-8");   
BufferedReader br = new BufferedReader(isr);   
String str = br.readLine();  
br.close();

java.lang.Object
  - java.io.Reader
    - java.io.InputStreamReader
      - java.io.FileReader

When to use: Usually this could be easier as we can use Scanner after JDK 1.5 (Be careful to charset problem)

Example:

FileReader fr = new FileReader("file.txt");
BufferedReader br = new BufferedReader(fr);
Scanner sc = new Scanner(fr);
int i = sc.nextInt();
String str = br.readLine();
br.close();

Writing:

The class hierachy is symmetrical to reading.

Example:

FileWriter fw = new FileWriter("test.txt");
fw.write("Something");
fw.close();

(Or PrintWriter can be used but it doesn't throw IOException)

OutputStreamWriter osw = new OutputStreamWriter(
    new  FileOutputStream("file.txt"), "utf-8");
osw.write("Something");
osw.close();