methods - Is Java "pass-by-reference" or "pass-by-value"? -
i thought java pass-by-reference; i've seen couple of blog posts (for example, this blog) claim it's not. don't think understand distinction they're making.
what explanation?
java pass-by-value. unfortunately, decided call location of object "reference". when pass value of object, passing reference it. confusing beginners.
it goes this:
public static void main( string[] args ) { dog adog = new dog("max"); // pass object foo foo(adog); // adog variable still pointing "max" dog when foo(...) returns adog.getname().equals("max"); // true, java passes value adog.getname().equals("fifi"); // false } public static void foo(dog d) { d.getname().equals("max"); // true // change d inside of foo() point new dog instance "fifi" d = new dog("fifi"); d.getname().equals("fifi"); // true }
in example adog.getname()
still return "max"
. value adog
within main
not changed in function foo
dog
"fifi"
object reference passed value. if passed reference, adog.getname()
in main
return "fifi"
after call foo
.
likewise:
public static void main( string[] args ) { dog adog = new dog("max"); foo(adog); // when foo(...) returns, name of dog has been changed "fifi" adog.getname().equals("fifi"); // true } public static void foo(dog d) { d.getname().equals("max"); // true // changes name of d "fifi" d.setname("fifi"); }
in above example, fifi
dog's name after call foo(adog)
because object's name set inside of foo(...)
. operations foo
performs on d
such that, practical purposes, performed on adog
(except when d
changed point different dog
instance d = new dog("boxer")
).
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