Question

Say I have an array of integers,

int[] array = new int[7];
for(int i = 0; i < 7; i++)
{
array[i] = i;
}

Now i want to get only the first four numbers in that array, and turn put that into another array.

So I really want something like…

newArray = array[0-3].

I know that syntax is wrong, but I’m just giving the general idea of what I’m trying to do, is anything like that possible? Or do i have to create a loop and add it manually into the newArray?

Answer 1

Method 1

int[] newArr = new int[4];
System.arraycopy(array, 0, newArr, 0, 4);

The method takes five arguments:

1. src: The source array.
2. srcPosition: The position in the source from where you wish to begin
   copying.
3. des: The destination array.
4. desPosition: The position in the destination array to where the copy
   should start.
5. length: The number of elements to be copied.

This method throws a NullPointerException if either of src or des are null.
It also throws an ArrayStoreException in the following cases:

• If the src is not an array.
• If the des is not an array.
• If src and des are arrays of different data types.

Method 2

Utilize

Arrays.copyOf(array,4) to copy the first 4 elements, truncating the rest.

of

Arrays.copyOfRange(array,1,5) to copy elements 1-4 if you need the middle of an array.