How to Convert Primitive Arrays to Wrapper Arrays in Java?

What is the most efficient method to convert an array of primitives into an array of their corresponding wrapper classes in Java?

In Java, converting an array of primitives such as `byte[]` to an array of their corresponding wrapper types like `Byte[]` can be achieved efficiently using streams or utilizing utility methods. Below, I outline several approaches to handle this conversion elegantly.

// Using Java Streams to convert byte[] to Byte[]
byte[] primitiveArray = {1, 2, 3, 4};
Byte[] wrapperArray = Arrays.stream(primitiveArray)  
                           .boxed()  
                           .toArray(Byte[]::new);  

// Manual conversion using a for loop  
Byte[] wrapperArrayManual = new Byte[primitiveArray.length];
for (int i = 0; i < primitiveArray.length; i++) {
    wrapperArrayManual[i] = primitiveArray[i];
}

Causes

• For better flexibility when working with collections that require objects, such as `ArrayList`.
• To utilize Java Collections Framework which only supports objects, not primitives.

Solutions

• Using Java 8 Streams for a concise and functional approach.
• Looping manually through the array for better control and performance in certain cases. Additionally, utility methods can encapsulate this logic.

Mistake: Not using the correct method reference in streams, leading to compilation errors.

Solution: Ensure you use the appropriate method reference such as `Byte[]::new`.

Mistake: Assuming primitive types behave like their wrapper counterparts in collections, causing unexpected `NullPointerExceptions`.

Solution: Always ensure the conversion is completed, especially when adding to collections.