File Reader

Class FileReader

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

All Implemented Interfaces:

Closeable, Readable

By using FileReader we can read character data from file.

Constructors: 

1. FileReader fr=new FileReader(String name);

/* Creates a new FileReader, given the name of the file to read from */

2. FileReader fr=new FileReader(File f);

/* Creates a new FileReader, given the File to read from*/

3. FileReader fr=new FileReader(FileDescriptor fd);

/* Creates a new FileReader, given the FileDescriptor to read from */

Method Summary

 

Methods inherited from class java.io.InputStreamReader
close, getEncoding, read, read, ready

 

Methods inherited from class java.io.Reader
mark, markSupported, read, read, reset, skip

 

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Most Frequently Used Methods: 

1. int read() throws IOException : It attempts to read next character from the file, if it is available it returns UNICODE and if it is not available then this method returns -1

2. int read (char[] ch) throws IOException : To read characters and place it into a char[]. This method returns no of characters read from the file to the char[].

3. void close() : Closes the stream and releases any system resources associated with it.

Now lets check the methods usage with an example 

package com.java.everythingaboutselenium;

import java.io.File;

import java.io.IOException;

class FileReaderDemo

{

public static void main(String[] args)

{

      File f=new File("FileReaderDemo.txt");

      FileReader fr=new FileReader(f);

      System.out.println(fr.read());

      /* This print the UNICODE of the first character */

      char[] ch=new char[(int)(f.length())];

      fr.read(ch);

     /*File Data copied to Array */

      for (char c1:ch)

     {

         System.out.println(c1);

      }

      FileReader fr1=new FileReader(f);

      int i=fr1.read();

      while(i!=-1)

     {

         System.out.println((char)i);

         i=fr1.read();

      }

}