Java.io.FileInputStream.read() Method

Description

The java.io.FileInputStream.read(byte[] b) reads upto the b.length from this file input stream to the array of bytes. The method blocks until some input is available.

Declaration

Following is the declaration for java.io.FileInputStream.read(byte[] b) method:

public int read(byte[] b)

Parameters

• b - the byte array into which data is read.

Return Value

The methods returns the total number of bytes read into the buffer, or -1 if there is no more data to be read.

Exception

• IOException - If an I/O error occurs

Example

The following example shows the usage of java.io.FileInputStream.read(byte[] b) method.

package com.tutorialspoint;

import java.io.IOException;
import java.io.FileInputStream;

public class FileInputStreamDemo {
   public static void main(String[] args) throws IOException {
      
      FileInputStream fis = null;
      int i = 0;
      char c;
      byte[] bs = new byte[4];
      
      try{
         // create new file input stream
         fis = new FileInputStream("C://test.txt");
         
         // read bytes to the buffer
         i=fis.read(bs);
         
         // prints
         System.out.println("Number of bytes read: "+i);
         System.out.print("Bytes read: ");
         
         // for each byte in buffer
         for(byte b:bs)
         {
            // converts byte to character
            c=(char)b;
            
            // print
            System.out.print(c);
         }   
      }catch(Exception ex){
         // if any error occurs
         ex.printStackTrace();
      }finally{
         
         // releases all system resources from the streams
         if(fis!=null)
            fis.close();
      }
   }
}

Assuming we have a text file c:/test.txt, which has the following content. This file will be used as an input for our example program:

ABCDEF

Let us compile and run the above program, this will produce the following result:

Number of bytes read: 4
Bytes read: ABCD