从Java的构造函数创建对象时出现奇怪的行为

Question

I have a constructor which takes some params something like this

public XYZ(Long param1, boolean param2, Long param3){
  //...
}

when I try to create an object for this class by using new Operator like

XYZ xyz = new XYZ(1L, false,4L);

(notice the absence of space between false,4)

My param3 is always getting passed as null to the constructor in java 7. But while I try to evaluate the same expression while debugging in IntelliJ Idea, the object creation works as normal.

Is this behavior happening due to comma operator ? . I tried reading java language specs but couldn't find anything regarding this. More over it is written at several places that while object creation comma(,) works as a Separator not as an operator.

If I put normal spacing between params everything works normal. Can somebody explain this behavior. If the comma is working as operator then shouldn't there be a compile time error while object creation ?

EDIT:

Thanks every one for your answers. I am not able to able to replicate the issue outside the production environment, perhaps I am overlooking something important. Please mark this Question as Closed.

Answer 1

This is what I tried:

public class TestClass {

    public TestClass(Long param1, boolean param2, Long param3) {
        System.out.println(param1);
        System.out.println(param2);
        System.out.println(param3);
    }

    public static void main(String[] args) {
        new TestClass(1L, false,2L);
    }
}

And the output is:

1
false
2

Maybe you need to give us more information?

Answer 2

Java is Strong typed language. In your code example this means that if your class has single constructor with 3 parameters, then the compiler ensures that the constructor must be explicitly called with 3 parameters. Run time situations in which a comma is seen as the operator can not happen, because in that case the result is only 2 parameters.

In Weak typed languages like JavaScript two parameters instead of three can produce null as the third parameter, but not in Java.

So the answer to your question is This cannot happen in Java .