Java.io.ByteArrayInputStream.read() Method

Description

The java.io.ByteArrayInputStream.read(byte[] b, int off, int len) method reads len bytes of data from this input stream into an array of bytes. The read() method doesn't block

Declaration

Following is the declaration for java.io.ByteArrayInputStream.read(byte[] b, int off, int len) method:

public int read(byte[] b, int off, int len)

Parameters

• b -- data is read into this buffer

• off -- Offset to start at destination array b

• len -- maximum number of bytes read

Return Value

Number of bytes read into the buffer. Returns -1 if the stream has reached it's end.

Exception

• NullPointerException -- If b is null.

• IndexOutOfBoundsException -- If len is greater than input stream's length after offset, off is negative, or len is negative.

Example

The following example shows the usage of java.io.ByteArrayInputStream.read(byte[] b, int off, int len) method.

package com.tutorialspoint;

import java.io.ByteArrayInputStream;
import java.io.IOException;

public class ByteArrayInputStreamDemo {
   public static void main(String[] args) throws IOException {
      
      byte[] buf = {65, 66, 67, 68, 69};
      ByteArrayInputStream bais = null;
      
      try{
         
         // create new byte array input stream
         bais = new ByteArrayInputStream(buf);
      
         // create buffer
         byte[] b = new byte[4];
         int num = bais.read(b, 2, 2);
         
         // number of bytes read
         System.out.println("Bytes read: "+num);
         
         // for each byte in a buffer
         for (byte s :b)
         {
            // covert byte to char
            char c = (char)s;
            
            // prints byte
            System.out.print(s);
            
            if(s==0)
               
               // if byte is 0
               System.out.println(": Null");
            else
               
               // if byte is not 0
               System.out.println(": "+c);
         }
      }catch(Exception e){
         
         // if I/O error occurs
         e.printStackTrace();
      }finally{
         if(bais!=null)
            bais.close();
      }   
   }
}

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

Bytes read: 2
0: Null
0: Null
65: A
66: B