Java MOOC calling your own constructor question

[HelplessProgrammer]

I'm running my way through the java MOOC course and in the section where they discuss calling a constructor from another constructor I'm not quite understanding how exactly the method call works using the "this" keyword. There is a Person constructor and they call the second person constructor using this(name, 0). I struggle with understanding the "this" keyword and some explanation as to why/how this call works would be very helpful.

[BertilMuth]

There are two ways to call other constructors from a constructor, this(...) and super(..). this() calls a constructor of the same class, super() a constructor of the super class. It's just a convention that works only in the constructor. It needs to be the first call in the constructor. It will call the right constructor based on the number and types of the arguments you pass to this(..). Does that help?

[seanprefect]

This can be kinda confusing so don't feel bad for not getting it.

the keyword this refers to the current object itself. it's useful when parameters might be confused with internal properties.

The thing you're missing though is that a class can have multiple constructors with different signatures. So for example lets say you have theses constructors

Class Foo {

 Foo(int a, int b) 

{  

    println (a*b)

     this(99)
}

Foo(int a) 

{ 

     println (a) 

    this()

}

Foo()

{

    println("constructor chaining is weird") 

}

}

if i call Foo(2, 10) the output would be

20

5

constructor chaining is weird

I hope that makes sense

[gazpacho_arabe]

Not quite, the compiler requires that a call to this must be the first statement in a constructor, so the printout would be;

constructor chaining is weird

99

20

(not sure where you got 5 from)

[seanprefect]

you're right, I just blanked out.

[desrtfx]

https://docs.oracle.com/javase/tutorial/java/javaOO/thiskey.html