How do I update the long value of java.lang.Long in Java?

Question

I'm passing in a java.lang.Long class instance to a method (obviously as reference), and I'm wondering whether it's possible to modify its long value so that the caller can get the modified value. I've looked at the documentation for java.lang.Long, but there doesn't seem to exist any setter method for this type. Is this correct?

score 6 · Accepted Answer · edited May 23 '17 at 11:51

6

You can not change Long value. Its immutable. Check this and that for more info

edited May 23 '17 at 11:51

Community

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answered Mar 10 '13 at 14:57

BobTheBuilder

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Well not without hacking the VM via native code or reflection at any rate. Which of course is an EXTREMELY BAD IDEA. – Antimony Mar 10 '13 at 14:58

score 3 · Answer 2 · edited Dec 02 '15 at 06:58

3

java.lang.Long is a immutable, the only way is to reassign the modified value to the previous reference.

public Long someMethod(Long l) {
    l = watever;
    return l;
}

public void someOtherMethod() {
    Long l = 22235637334634263464L;
    l = someMethod(l);
}

edited Dec 02 '15 at 06:58

Ian2thedv

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answered Mar 10 '13 at 14:57

PermGenError

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@Chris but Long is final and immutable isn't it? – PermGenError Mar 10 '13 at 15:02
@Chris ahh i see, i edited it now. that was not my intention though :) – PermGenError Mar 10 '13 at 15:05

score 1 · Answer 3 · answered Feb 25 '14 at 11:21

1

Long is immutable in Java. You can change it inside a method in the following way:

Wrap it
Use AtomicLong
Return changed value and reasign it outside the method

answered Feb 25 '14 at 11:21

Alexander Bezrodniy

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How do I update the long value of java.lang.Long in Java?

3 Answers3