Java method to swap primitives

Question

how do I make my swap function in java if there is no method by which we can pass by reference? Could somebody give me a code?

swap(int a, int b) {      int temp = a;      a = b;      b = temp; } 

But the changes wont be reflected back since java passes parameters by value.

Answer 1

I think this is the closest you can get to a simple swap, but it does not have a straightforward usage pattern:

int swap(int a, int b) {  // usage: y = swap(x, x=y);    return a; }  y = swap(x, x=y); 

It relies on the fact that x will pass into swap before y is assigned to x, then x is returned and assigned to y.

You can make it generic and swap any number of objects of the same type:

<T> T swap(T... args) {   // usage: z = swap(a, a=b, b=c, ... y=z);     return args[0]; }  c = swap(a, a=b, b=c) 

Answer 2

You can't create a method swap, so that after calling swap(x,y) the values of x and y will be swapped. You could create such a method for mutable classes by swapping their contents¹, but this would not change their object identity and you could not define a general method for this.

You can however write a method that swaps two items in an array or list if that's what you want.

¹ For example you could create a swap method that takes two lists and after executing the method, list x will have the previous contents of list y and list y will have the previous contents of list x.