Java method to swap primitives

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)

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.