Read Input From User and Write to File : BufferedWriter « File « Java Tutorial

1. Java Tutorial
2. File
3. BufferedWriter

import java.io.BufferedWriter;
import java.io.FileWriter;
import java.io.InputStream;

public class Main {
  public static void main(String[] args) throws Exception {
    InputStream in = System.in;
    BufferedWriter bw = new BufferedWriter(new FileWriter("output.txt"));

    int letter;

    while ((letter = in.read()) != -1) {
      bw.write((char) letter);
      bw.flush();
    }
  }
}