Do objects passed into methods need to be returned to be changed?

If I pass a object into a method and I change that object in that method will it keep its changes? I'm not sure if I've worded this right so I'll give an example:

public void methodThatChangesX(ClassWithVariableX var) {
    var.x = 5;
}

ExampleClass var = new ExampleClass(); 
//ExampleClass's x's default is 6

methodThatChangesX(var);

System.out.println("x = " + var.x);

Would var's x be 5 or 6? Is there a reason for this?