Java/File Input Output/Buffered Reader Writer

Creates a tiny text editor with BufferedReader

   <source lang="java">

import java.io.BufferedReader; import java.io.IOException; import java.io.InputStreamReader; class TinyEdit {

 public static void main(String args[]) throws IOException {
   BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
   String str[] = new String[100];
   System.out.println("Enter lines of text.");
   System.out.println("Enter "stop" to quit.");
   for (int i = 0; i < 100; i++) {
     str[i] = br.readLine();
     if (str[i].equals("stop"))
       break;
   }
   System.out.println("\nHere is your file:");
   for (int i = 0; i < 100; i++) {
     if (str[i].equals("stop"))
       break;
     System.out.println(str[i]);
   }
 }

}

</source>
   
  
 
  

how to read lines from a file and print these to the standard output stream

   <source lang="java">

import java.io.BufferedReader; import java.io.FileReader; import java.io.IOException; class FileReaderDemo {

 public static void main(String args[]) throws IOException {
   FileReader fr = new FileReader("FileReaderDemo.java");
   BufferedReader br = new BufferedReader(fr);
   String s;
   while ((s = br.readLine()) != null) {
     System.out.println(s);
   }
   fr.close();
 }

}

</source>
   
  
 
  

Read a string from console using a BufferedReader.

   <source lang="java">

import java.io.BufferedReader; import java.io.IOException; import java.io.InputStreamReader; class BRReadLines {

 public static void main(String args[]) throws IOException {
   BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
   String str;
   System.out.println("Enter lines of text.");
   System.out.println("Enter "stop" to quit.");
   do {
     str = br.readLine();
     System.out.println(str);
   } while (!str.equals("stop"));
 }

}

</source>
   
  
 
  

Use a BufferedReader to read characters from the console.

   <source lang="java">

import java.io.BufferedReader; import java.io.IOException; import java.io.InputStreamReader; class BRRead {

 public static void main(String args[]) throws IOException {
   char c;
   BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
   System.out.println("Enter characters, "q" to quit.");
   do {
     c = (char) br.read();
     System.out.println(c);
   } while (c != "q");
 }

}

</source>
   
  
 
  

Writing to a Text File

   <source lang="java">

import java.io.BufferedWriter; import java.io.File; import java.io.FileWriter; import java.io.IOException; import java.io.PrintWriter; public class WriteFile {

 public static void main(String[] args) {
   Product[] movies = new Product[10];
   movies[0] = new Product("L", 1946, 14.95);
   movies[1] = new Product("T", 1965, 12.95);
   movies[2] = new Product("Y", 1974, 16.95);
   movies[3] = new Product("T", 1975, 11.95);
   movies[4] = new Product("S", 1977, 17.95);
   movies[5] = new Product("B", 1987, 16.95);
   movies[6] = new Product("G", 1989, 14.95);
   movies[7] = new Product("A", 1995, 19.95);
   movies[8] = new Product("G", 1997, 14.95);
   movies[9] = new Product("R", 2001, 19.95);
   PrintWriter out = openWriter("movies.txt");
   for (Product m : movies)
     writeMovie(m, out);
   out.close();
 }
 private static PrintWriter openWriter(String name) {
   try {
     File file = new File(name);
     PrintWriter out = new PrintWriter(new BufferedWriter(new FileWriter(file)), true);
     return out;
   } catch (IOException e) {
     System.out.println("I/O Error");
     System.exit(0);
   }
   return null;
 }
 private static void writeMovie(Product m, PrintWriter out) {
   String line = m.title;
   line += "\t" + Integer.toString(m.year);
   line += "\t" + Double.toString(m.price);
   out.println(line);
 }

} class Product {

 public String title;
 public int year;
 public double price;
 public Product(String title, int year, double price) {
   this.title = title;
   this.year = year;
   this.price = price;
 }

}

</source>