java - Unable to understand the issue "call By Reference" -

this question has answer here:

• is java “pass-by-reference” or “pass-by-value”? 74 answers

in java, object reference used call reference , variables used call value.

here’s example:

class foo{     int x;     int y; }     public class callbyref {     public static void main(string[] args) {                     foo foo = new foo();         foo.x=5;         foo.y=10;         system.out.println(foo.x+", "+foo.y);         getfoo(foo);         system.out.println(foo.x+", "+foo.y);     }         static void getfoo(foo f){         f.x=2;         f=new foo();         f.x=10;     } } 

output:

5, 10     2, 10 

why happend?

x should 10 modified value f.x=10

is correct f=new foo() create new object in heap , not point prevoise reference?

in method getfoo, variable f local variable.

when call getfoo(foo) main, variable indeed refers foo.

but once set f = new foo(), refers different object.

therefore, @ point, changing f.x not affect foo.x.