Java byte[] pointer conversion

Question

I have a method given these arguments

int read( byte result[], int offset, int size ) {
}

From which I need to call a different method:

int read( byte result[], int length ) {
}

I know how to convert an array in C++ with an offset, but I have no idea how to do this in Java.

raw pointers are not supported by java. use System.arrayCopy or Arrays.copyOf or manual copy — Gurwinder Singh
– Gurwinder Singh, Commented Dec 7, 2016 at 16:58

Andreas · Accepted Answer · 2016-12-07 17:07:16Z

1

You can't. You have to create a copy of the sub-array.

Easiest way to do that, is to use one of the Arrays.copyOfRange(xxx[] original, int from, int to) methods, where xxx is a primitive type or any object type.

If needed, you can copy updated values back to the original array using System.arraycopy().

In your case, the parameter is actually output-only, so you just create a new array, call the method with it, then copy the values to the original array, e.g.

int read( byte result[], int offset, int size ) {
    if (offset == 0)
        return read(result, size);
    byte[] buf = new byte[size];
    int bytesRead = read(buf, size);
    System.arraycopy(buf, 0, result, offset, bytesRead);
    return bytesRead;
}

edited Dec 7, 2016 at 17:07

answered Dec 7, 2016 at 17:00

Andreas

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