Java Program to Convert the InputStream into Byte Array

In the following examples of Java program to convert an InputStream to a byte array :

Program :

import java.io.InputStream;
import java.util.Arrays;
import java.io.ByteArrayInputStream;


public class Main {

  public static void main(String args[]) {

    try {

      // create an input stream
      byte[] input = {1, 2, 3, 4};
      InputStream stream = new ByteArrayInputStream(input);
      System.out.println("Input Stream: " + stream);

      // convert the input stream to byte array
      byte[] array = stream.readAllBytes();
      System.out.println("Byte Array: " + Arrays.toString(array));

      stream.close();
    }

    catch (Exception e) {
      e.getStackTrace();
    }
  }
}

Output :

Input Stream: java.io.ByteArrayInputStream@19469ea2
Byte Array: [1, 2, 3, 4]

In the above example, we have created an input stream named stream. Note the line,

byte[] array = stream.readAllBytes();

Here, the readAllBytes() method returns all the data from the stream and stores in the byte array.

Convert InputStream to Byte Array using Output Stream :

Program :

import java.io.InputStream;
import java.util.Arrays;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;


public class Main {

  public static void main(String args[]) {

    try {

      // create an input stream
      byte[] input = {1, 2, 3, 4};
      InputStream stream = new ByteArrayInputStream(input);
      System.out.println("Input Stream: " + stream);

      // create an output stream
      ByteArrayOutputStream output = new ByteArrayOutputStream();
      // create a byte array to store input stream
      byte[] array = new byte[4];
      int i;

      // read all data from input stream to array
      while ((i = stream.read(array, 0, array.length)) != -1) {

        // write all data from array to output
        output.write(array, 0, i);
      }

      byte[] data = output.toByteArray();

      // convert the input stream to byte array
      System.out.println("Byte Array: " + Arrays.toString(data));
      stream.close();
    }

    catch (Exception e) {
      e.getStackTrace();
    }
  }
}

Output :

Input Stream: java.io.ByteArrayInputStream@19469ea2
Byte Array: [1, 2, 3, 4]

In the above example, we have created an input stream from the array input. Notice the expression,

stream.read(array, 0, array.length)

Here, all elements from stream are stored in array, starting from index 0. We then store all elements of array to the output stream named output.