BufferedWriter

A BufferedWriter is a Writer that buffers ouput.

A BufferedWriter has these two constructors:

BufferedWriter(Writer outputStream): creates a buffered stream using a buffer with a default size.
BufferedWriter(Writer outputStream, int bufSize): the size of the buffer is passed in bufSize.

void close(): Closes the stream, flushing it first.
void flush(): Flushes the stream.
void newLine(): Writes a line separator.
void write(char[] cbuf, int off, int len): Writes a portion of an array of characters.
void write(int c): Writes a single character.
void write(String s, int off, int len): Writes a portion of a String.

Revised from Open JDK source code


import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.io.StringReader;

public class Main {
  public static void main(String[] args) throws Exception {
    BufferedReader stdin = new BufferedReader(new InputStreamReader(System.in));
    System.out.println(stdin.readLine());
    BufferedReader in = new BufferedReader(new FileReader("Main.java"));
    String s, s2 = new String();
    while ((s = in.readLine()) != null)
      s2 += s + "\n";
    in.close();
    StringReader in1 = new StringReader(s2);
    int c;
    while ((c = in1.read()) != -1)
      System.out.print((char) c);
    BufferedReader in2 = new BufferedReader(new StringReader(s2));
    PrintWriter out1 = new PrintWriter(new BufferedWriter(new FileWriter(
        "IODemo.out")));
    int lineCount = 1;
    while ((s = in2.readLine()) != null)
      out1.println(lineCount++ + ": " + s);
    out1.close();
  }
}

Create BufferedWriter from standard System.out


import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;

public class Main {
  public static void main(String[] args) throws Exception {
    BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
    String strLine = in.readLine();
    BufferedWriter out = new BufferedWriter(new OutputStreamWriter(System.out));
    out.write(strLine, 0, strLine.length());
    out.flush();
    in.close();
    out.close();
  }
}

Write String to a file with BufferedWriter


import java.io.BufferedWriter;
import java.io.File;
import java.io.FileWriter;
import java.io.Writer;

public class Main {
  public static void main(String[] args) throws Exception {
    Writer writer = null;

    String text = "This is a text file";

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

  }
}

Home
Java Book
File Stream

BufferedWriter: