Arrays are fixed length, so you have various alternatives. Here are a couple:
a) Create a new array with the size of the others and copy all the elements manually.
healthMessagesAll = new HealthMessage[healthMessages1.length + healthMessages2.length];
int i = 0;
for (HealthMessage msg : healthMessases1)
{
healthMessagesAll[i] = msg;
i++;
}
for (HealthMessage msg : healthMessages2)
{
healthMessagesAll[i] = msg;
i++;
}
b) Use the methods provided by the Arrays class. You can convert the array to a List, or copy elements around in bulk. Have a look at the functions it provides and choose the one that suits you.
UPDATE
Seeing your comment about duplicates. You might want to put everything in a Set which guarantees uniqueness. If you add the same element twice, it won't be added the second time.
You can then convert the Set back to an array if you explicitly require an array with its own toArray() method.
As suggested by other respondents, System.arraycopy() helps you copy the contents of the elements too, so its a shorter version of my alternative (a) above.
