Double array to int array?

[Jody Monahan]

Hi all,

I was just wondering is there any way to convert a double array to an integer array?

Thanks in advance,
Jody

[Ernest Friedman-Hill]

Just with a loop:

final int[] intArray = new int[doubleArray.length];
for (int i=0; i<intArray.length; ++i)
    intArray[i] = (int) doubleArray[i];

>

[Jelle Klap]

Casting is obviously not an option, so that leaves iterating the source array, casting the element at every iteration and storing it in the destination array of the desired component type.
Unfortunately System.arraycopy() won't help you here and neither will any of the utility methods provided by the java.util.Arrays class, so you'll have to do code the loop-convert-store routine yourself.

Edit: Sloooooooow.

[Rory Evans]

Ernest Friedman-Hill wrote:Just with a loop:

final int[] intArray = new int[doubleArray.length];
for (int i=0; i<intArray.length; ++i)
    intArray[i] = (int) doubleArray[i];

>

In the above code, shouldn't it read

 for (int i=0; i<intArray.length; i++)   

Otherwise, the loop will start with element 1 of the array rather than element 0.

[Rob Spoor]

No, the ++i will still be executed after all other code in the loop body has executed.

[Ernest Friedman-Hill]

Not that it matters too much most of the time, but you should always use ++i, not i++, in loops like this, because i++ implies just a tiny bit more work for the computer. ++i means "add one to the variable, and use the result", while i++ means "make a copy of the variable, increment the variable, and use the copy." In a very tight loop, making that copy can make a measurable difference (except when the vm is smart enough to realize the copy isn't needed, and optimizes it away.)

[Jody Monahan]

Cheers everyone, thanks for all of the replies!