java Can i create a string that is defined as null in one line?

Question

I'd like to pass a String parameter as "null"

However, this is for the super method in a constructor - so i cannot do

String s = null;
super(s);

I cannot just do

super(null)

as this will result in an ambiguous method call. I don't want to have an instance variable that is null for this either, that seems inelegant.

Is there a way to create a null String?

NB

 new String(null) //does not compile

@AndrewThompson: that should be an answer (as simple as it might look to you). — JB Nizet
– JB Nizet, Commented Dec 14, 2012 at 11:45
@JBNizet Ehh.. (shrugs) I'm a bit late coming back to this. Now it's been put as an answer by others, it seems redundant. — Andrew Thompson
– Andrew Thompson, Commented Dec 14, 2012 at 12:05

codeMan · Accepted Answer · 2012-12-14 11:46:26Z

5

Just do this

super((String)null);

answered Dec 14, 2012 at 11:46

codeMan

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AlexWien · Accepted Answer · 2012-12-14 11:50:38Z

3

CodeMan posted the correct answer, another solution, move away from null, and consider initializing with Empty string

super("");

this would avoid a null check later.

answered Dec 14, 2012 at 11:50

AlexWien

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2 Comments

bharal Over a year ago

this is true - there is a null check though, and in case we ever do want to do something with a non-null and empty string i thought i'd stay away from this.

Nathan Over a year ago

this conversation I like the bug with the string concatenating but i also like the fact null doesn't go on the heap (though being efficient in java seems a bit pointless).

madth3 · Accepted Answer · 2012-12-14 14:29:40Z

1

The problem you have is that the compiler do not know which constructor should be used.

String has various single parameter constructor.

 String(String)
 String(char value[])
 String(StringBuffer)
 String(StringReader)

When you use String(null), it is unknown which should be used.

Remember when you use a null as argument (in a method or constructor), you should always forward it with cast to desired type.

new String((String) null);

edited Dec 14, 2012 at 14:29

madth3

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answered Dec 14, 2012 at 12:04

Damian Leszczyński - Vash

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