NullPointerException in ByteBuffer

Question

byteArray = new byte[10000];

-- some code here ----

byteBuffer.wrap(byteArray);
for (int i=0; byteBuffer.hasRemaining(); i++)
{
    shortArray[i] = byteBuffer.getShort();
    System.out.println(shortArray[i]);
}

The byteBuffer.hasRemaining() gets flagged with a NullPointerException although I have provided it with a backing array.

What is the problem here?

where you initialize `byteBuffer`? – Nikolay Kuznetsov Dec 26 '12 at 07:32 — Nikolay Kuznetsov, Dec 26 '12 at 07:32

score 3 · Accepted Answer · answered Dec 26 '12 at 07:33

3

Please, check how you initialize byteBuffer it should be something like this since wrap is a static method

byte[] byteArray = new byte[10000];    
ByteBuffer byteBuffer = ByteBuffer.wrap(byteArray);

answered Dec 26 '12 at 07:33

Nikolay Kuznetsov

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What happens when you call `static` methods on `null` objects? – John Dvorak Dec 26 '12 at 07:35
@JanDvorak Alright, I realized my mistake :) Next, getting Shorts out of the buffer. `getShort()` is abstract. – An SO User Dec 26 '12 at 07:35
@JanDvorak, really no idea. Please, let us now. – Nikolay Kuznetsov Dec 26 '12 at 07:36
3

@LittleChild `getShort` is abstract but it still needs to be implemented by concrete subclasses (of which `wrap` returns one). Try calling it. – John Dvorak Dec 26 '12 at 07:38
3

@NikolayKuznetsov http://stackoverflow.com/questions/3293353/how-come-invoking-a-static-method-on-a-null-reference-doesnt-throw-nullpointe – John Dvorak Dec 26 '12 at 07:40

score 1 · Answer 2 · answered Dec 26 '12 at 07:46

1

The code seems OK. I suspect this is (due to some bug) because byteBuffer variable = null

answered Dec 26 '12 at 07:46

Evgeniy Dorofeev

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`hasRemaining` is not static, so the exception does get thrown at that point, so it's not a bug. – John Dvorak Dec 26 '12 at 07:50

NullPointerException in ByteBuffer

2 Answers2