Java.io.InputStream.read() Method


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Description

The java.io.InputStream.read(byte[] b) method reads b.length number of bytes from the input stream to the buffer array b. The bytes read is returned as integer.

Declaration

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

public int read(byte[] b)

Parameters

b − The destination byte array.

Return Value

The method returns the number of bytes actually read into the buffer, or -1 if the end of the stream is reached.

Exception

  • IOException − If an I/O error occurs.

  • NullPointerException − If b is null.

Example

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

package com.tutorialspoint;

import java.io.FileInputStream;
import java.io.InputStream;

public class InputStreamDemo {

   public static void main(String[] args) throws Exception {
      InputStream is = null;
      byte[] buffer = new byte[5];
      char c;
      
      try {
      
         // new input stream created
         is = new FileInputStream("C://test.txt");
         
         System.out.println("Characters printed:");
         
         // read stream data into buffer
         is.read(buffer);
         
         // for each byte in the buffer
         for(byte b:buffer) {
         
            // convert byte to character
            c = (char)b;
            
            // prints character
            System.out.print(c);
         }
         
      } catch(Exception e) {
         
         // if any I/O error occurs
         e.printStackTrace();
      } finally {
         
         // releases system resources associated with this stream
         if(is!=null)
            is.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 −

ABCDE

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

Characters printed:
ABCDE

java_io_inputstream.htm

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