Private Constructor in Java Class.

[Ivan Franko]

When I investigate source code one project I found class, something like this:

class Test {
	private final String someString;
	private final Integer someInteger;

	private Test() {
		this.someString = null;
		this.someInteger = null;
	}

	public Test(String s, Integer i) {
		this.someString = s;
		this.someInteger = i;

	}

	public String getSomeString() {
		return someString;

	}

	public Integer getSomeInteger() {
		return someInteger;

	}

}

My question:

Why role this peace of code:

	private Test() {
		this.someString = null;
		this.someInteger = null;
	}

?

[Sagar Rohankar]

Doesn't really make sense, See Rob and Campbell reply

[Rob Spoor]

But because another constructor is created manually (that takes two Strings), no default constructor will be created automatically. Therefore there is no need to "get rid of it" by creating a final one.

[lokesh sree]

Since an overloaded constructor is written in the class, the default constructor also had to be provided.
But the author did not want the fields to be left uninitialized and hence made the constructor private and inaccessible to other classes.

But, I believe the lines

         
this.someString = null;  
this.someInteger = null;  

are not required inside the private default constructor and can be removed. Is that correct?

[Campbell Ritchie]

It's not a default constructor; that would have package-private access.
I think that private constructor is a mistake. The reason the two fields are initialised is because they are final and the compiler error said they must be initialised.

[Sagar Rohankar]

Rob Spoor wrote:But because another constructor is created manually (that takes two Strings), no default constructor will be created automatically. Therefore there is no need to "get rid of it" by creating a final one.

My bad, I somehow missed that simple thing. Thanks Rob!