Java: Converting a char to a string

Question

I have just done this in eclipse:

String firstInput = removeSpaces(myIn.readLine());
String first = new String(firstInput.charAt(0));

However, eclipse complains that:

The constructor String(char) is undefined

How do I convert a char to a string then??

Thanks

EDIT

I tried the substring method but it didn't work for some reason but gandalf's way works for me just fine! Very straightforward!

Out of curiosity, what "didn't work"? What error message did it give you? — Amber
– Amber, Commented Dec 1, 2009 at 22:43

Gandalf · Accepted Answer · 2009-12-01 22:36:37Z

15

Easiest way?

String x = 'c'+"";

or of course

String.valueOf('c');

answered Dec 1, 2009 at 22:36

Gandalf

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4 Comments

Abs Over a year ago

Worked and I understand it. :) It seems a little strange though, maybe because its too easy!

Steve Kuo Over a year ago

Concatenating 'c' to "" is less desireable as it uses StringBuilder. String.valueOf is the preferred approach.

Stephen C Over a year ago

@Steve - maybe, maybe not. It depends on how smart the compiler is. The JLS allows a Java compiler to rewrite String concatenation expressions to the most efficient equivalent code sequence.

Steve Kuo Over a year ago

@Stephen I used javac and javap (1.6.0_10) and 'C'+"" results in using StringBuilder. So while the JLS may allow rewriting, the Sun compiler doesn't.

Amber · Accepted Answer · 2009-12-01 22:39:50Z

4

Instead of...

String first = new String(firstInput.charAt(0));

you could use...

String first = firstInput.substring(0,1);

substring(begin,end) gives you a segment of a string - in this case, 1 character.

answered Dec 1, 2009 at 22:39

Amber

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Comments

haffax · Accepted Answer · 2009-12-01 22:38:52Z

3

String x = String.valueOf('c');`

That's the most straight forward way.

answered Dec 1, 2009 at 22:38

haffax

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Comments

karoberts · Accepted Answer · 2009-12-01 22:40:07Z

3

Why not use substring?

String first = firstInput.substring(0, 1);

answered Dec 1, 2009 at 22:40

karoberts

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Comments

Alexander Pogrebnyak · Accepted Answer · 2009-12-01 22:39:14Z

2

String firstInput = removeSpaces(myIn.readLine());
String first = firstInput.substring(0,1);

This has an advantage that no new storage is allocated.

answered Dec 1, 2009 at 22:39

Alexander Pogrebnyak

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5 Comments

Stephen C Over a year ago

-1 - FALSE. New storage is allocated to represent the String object created by substring. String.valueOf(char) potentially doesn't allocate any new space ... if the char is less than 127 and you've already called valueOf for that char.

Alexander Pogrebnyak Over a year ago

@Stephen. TRUE. At least with Sun SDK. It uses package private String constructor that does offsets magic on the same char[] array that firstInput is using. Please check SDK source code for that.

Stephen C Over a year ago

@Alexander. The private String constructor returns a new String object, so NEW STORAGE IS BEING ALLOCATED. On a 32 bit JVM, it is at least 4 words + the object header overhead. Jeez ...

Alexander Pogrebnyak Over a year ago

@Stephen. I've added a reply to your answer stackoverflow.com/questions/1829421/…. I don't know what JDK you are using, but with regards to Sun 1.6, you cannot go from char to String without allocating String at runtime. substring at least does not allocate a new char[] array for internal storage. Jeez...

Alexander Pogrebnyak Over a year ago

@Stephen. After you've deleted your wrong answer, have a decency to remove your slandering comments.

Jonathan Holloway · Accepted Answer · 2009-12-01 22:40:26Z

1

You could do this:

String s = Character.toString('k');

answered Dec 1, 2009 at 22:40

Jonathan Holloway

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2 Comments

Stephen C Over a year ago

That just calls Character.valueOf('k')

Jonathan Holloway Over a year ago

No it doesn't - not at all, it calls String.valueOf(char);

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