Java Guava | Bytes.toArray() method with Examples

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The toArray() method of Bytes Class in the Guava library is used to convert the byte values, passed as the parameter to this method, into a Byte Array. These byte values are passed as a Collection to this method. This method returns a Byte array.

Syntax:

public static byte[] toArray(Collection<? extends Number> collection)

Parameters: This method accepts a mandatory parameter collection which is the collection of byte values to be converted in to a Byte array.

Return Value: This method returns a byte array containing the same values as a collection, in the same order.

Exceptions: This method throws NullPointerException if the passed collection or any of its elements is null.

Below programs illustrate the use of toArray() method:

Example 1:

// Java code to show implementation of
// Guava's Bytes.toArray() method
  
import com.google.common.primitives.Bytes;
import java.util.Arrays;
import java.util.List;
  
class GFG {
  
    // Driver's code
    public static void main(String[] args)
    {
  
        // Creating a List of Bytes
        List<Byte> myList
            = Arrays.asList((byte)1,
                            (byte)2,
                            (byte)3,
                            (byte)4,
                            (byte)5);
  
        // Using Bytes.toArray() method to convert
        // a List or Set of Byte to an array
        // of Byte
        byte[] arr = Bytes.toArray(myList);
  
        // Displaying an array containing each
        // value of collection,
        // converted to a byte value
        System.out.println(Arrays.toString(arr));
    }
}

Output:

[1, 2, 3, 4, 5]

Example 2:

// Java code to show implementation of
// Guava's Bytes.toArray() method
  
import com.google.common.primitives.Bytes;
import java.util.Arrays;
import java.util.List;
  
class GFG {
  
    // Driver's code
    public static void main(String[] args)
    {
  
        try {
  
            // Creating a List of Bytes
            List<Byte> myList
                = Arrays.asList((byte)2,
                                (byte)4,
                                null);
  
            // Using Bytes.toArray() method
            // to convert a List or Set of Byte
            // to an array of Byte.
            // This should raise "NullPointerException"
            // as the collection contains
            // "null" as an element
            byte[] arr = Bytes.toArray(myList);
  
            // Displaying an array containing each
            // value of collection,
            // converted to a byte value
            System.out.println(Arrays.toString(arr));
        }
        catch (Exception e) {
            System.out.println(e);
        }
    }
}