Recursive constructor invocation

[warren li]

Hi,

I have the following code:

class Dummy {
    private String name;
 
    public Dummy(){
        this("dummy");
    }
 
    public Dummy( String d ){
        this();
    }
}
class TestThis{
    public static void main(String[] args){
        new Dummy();
    }
}

I am using "javac 1.5.0_06". The compiler spits out the following error:
TestThis.java:9: recursive constructor invocation
public Dummy( String d ){
^
1 error

The excerpt from book "SCJP 5 Study Guide" is "your compiler may not actually catch the problem (it varies depending on your compiler, but most won't catch the problem).

for the following code:

class D2{
    public void doStuff(){
        doStuff2();
    }
    public void doStuff2(){
        doStuff();
    }
}
 
class TestThis{
    public static void main(String[] args){
        D2 d = new  D2();
        d.doStuff();
    }
}

It compiles fine, of course runtime error.

Who shall we listen to for the recursive constructors case during the exam? Select it compiles, or select its compilation fails?

THanks.

[Akash Bhatt]

there would be one more option in the exam ... depends on the VM

[warren li]

Originally posted by Akash Bhatt:
there would be one more option in the exam ... depends on the VM

[vidya sagar]

hi warren

Compiler catches the recursive constructor call because at the compiler time it checks the way to reach the parentclass(in our case Object class).

Compiler automatically adds super in the first line of the every Constructor (provided we aren't given and this() is not in the first line of the constructor)

So in our case it cannot add super in both of the constructor because this() is present in the first line. so it throws error.

But in case of method,
Compiler just checks for syntax and other stuff(not a flow).

Correct me if i am wrong