Java List generics syntax for primitive types

Question

I want to make a growable array of bytes. I.e a list. In c# would usally do the following syntax

List<byte> mylist = new List<byte>();

where as in java this syntax does not work and I have googled around and found the below code

List myList = new ArrayList();

but that is not what I want. Any idea's where I am going wrong?

Solution 1

Use the wrapper class Byte:

List<Byte> mylist = new ArrayList<Byte>();

Then, because of autoboxing, you can still have:

for (byte b : mylist) {

}

Solution 2

You could also use TByteArrayList from the GNU Trove library.

Solution 3

You have a Byte class provided by the JRE.

This class is the corresponding class for the byte primitive type.

See here for primitive types.

You can do this :

List<Byte> myList = new ArrayList<Byte>();
byte b = 127;
myList.add(b);
b = 0; // resetting
b = myList.get(0); // => b = 127 again

As Michael pointed in the comments :

List<Byte> myList = new ArrayList<Byte>();
Byte b = null;
myList.add(b);
byte primitiveByte = myList.get(0);

results in :

Exception in thread "main" java.lang.NullPointerException
    at TestPrimitive.main(TestPrimitive.java:12)