BufferedReader

BufferedReader improves performance by buffering input. It has two constructors:

BufferedReader(Reader inputStream): creates a buffered character stream using a default buffer size.
BufferedReader(Reader inputStream, int bufSize): the size of the buffer is bufSize.

void close(): Closes the stream and releases any system resources associated with it.
void mark(int readAheadLimit): Marks the present position in the stream.
boolean markSupported(): Tells whether this stream supports the mark() operation, which it does.
int read(): Reads a single character.
int read(char[] cbuf, int off, int len): Reads characters into a portion of an array.
String readLine(): Reads a line of text.
boolean ready(): Tells whether this stream is ready to be read.
void reset(): Resets the stream to the most recent mark.
long skip(long n): Skips characters.

Revised from Open JDK source code


import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.URL;

public class Main {

  public static void main(String[] args) throws Exception {
    URL url = new URL("http://localhost:1776");
    BufferedReader in = new BufferedReader(new InputStreamReader(url.openStream()));
    String line;
    while ((line = in.readLine()) != null) {
      System.out.println(line);
    }
    in.close();
  }
}

Create BufferedReader from System.in


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();
  }
}

Create BufferedReader from InputStreamReader


import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Standard {

  public static void main(String args[]) throws IOException {
    BufferedReader cin = new BufferedReader(new InputStreamReader(System.in));
    String number;
    int total = 0;

    while ((number = cin.readLine()) != null) {
      try {
        total += Integer.parseInt(number);
      } catch (NumberFormatException e) {
        System.err.println("Invalid number in input");
        System.exit(1);
      }
    }
    System.out.println(total);
  }
}


import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;

public class Main {
  public static void main(String[] argv) {
    try {
      BufferedReader br = new BufferedReader(new FileReader(new File("c:\\a.txt")));
      StringBuilder sb = new StringBuilder();
      String line = br.readLine();
      while (line != null) {
        sb.append(line + "\n");
        line = br.readLine();
      }
      br.close();
      System.out.println(sb.toString());
    } catch (Exception e) {
      e.printStackTrace();
    }
  }
}

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