Converting Character[] to String

Question

What is the best way to convert a Character[] to char[] or a String ?

One way is to manually loop through the Character array presently in a for(char c : CharacterArray) loop , appending to a StringBuilder. StringBuilder seems to accept a Character[] directly also , but is that all to it ?

@Bhaskar, there is almost never a good reason to use a Character[] The best thing to do is to refactor your code so you don't have one in the first place. Use a char[] or a StringBuilder instead. — Peter Lawrey
– Peter Lawrey, Commented Jun 28, 2011 at 21:11
@Peter Lawrey: I have a generic type in which one generic type param has to be 'char' - I dont know any other way to handle this other than using a Character , which then lands me in the situation mentioned. — Bhaskar
– Bhaskar, Commented Jun 28, 2011 at 21:17
@Bhaskar, Instead of List<Character> you should use StringBuilder. What type of generic collection are you using? — Peter Lawrey
– Peter Lawrey, Commented Jun 28, 2011 at 21:20
@Peter Lawrey : Its a Map<Character,Integer>. I am analyzing text/words and storing the letters-freq map, to be processed further by other code. — Bhaskar
– Bhaskar, Commented Jun 28, 2011 at 21:23

JB Nizet · Accepted Answer · 2011-06-28 21:00:56Z

3

commons-lang has a toPrimitive method, but there's nothing like this in the standard API. The only way is to loop through the array and transform each Character into a char (and decide what to do with null values).

answered Jun 28, 2011 at 21:00

JB Nizet

694k94 gold badges1.3k silver badges1.3k bronze badges

Sign up to request clarification or add additional context in comments.

Comments

JustinKSU · Accepted Answer · 2011-06-28 21:52:05Z

2

I would recommend converting the Character[] to a char[] using a simple loop and then passing it into new String();

    Character[] characters = new Character[128];
    char[] chars = new char[characters.length];
    int length = characters.length;
    for(int i=0; i<length; i++) {
        chars[i] = characters[i].charValue();
    }
    String string = new String(chars);

Another alternative would be to create a StringBuilder and loop through and add each character individually.

    Character[] characters = new Character[128];
    StringBuilder sb = new StringBuilder(characters.length);
    for(Character c : characters) {
        sb.append(c);
    }
    String string = sb.toString();

I have a feeling the first approach might be more efficient, but I'm not sure.

edited Jun 28, 2011 at 21:52

answered Jun 28, 2011 at 21:00

JustinKSU

5,0192 gold badges32 silver badges53 bronze badges

5 Comments

Josh Lee Over a year ago

If you initialize the StringBuilder with enough capacity, the second way should be efficient.

Martijn Courteaux Over a year ago

True, the first one is much faster. The StringBuilder will each time recreate a new buffer of one character bigger than the previous one. I checked the Java source code of StringBuilder. Except when you construct the StringBuilder with the given size of the array. Then, there is no need for recreating the buffer. Then the performance will be the same.

ratchet freak Over a year ago

actually if you do new StringBuilder(characters.length); it will be the most efficient if the appends and unboxing are inlined by JIT as the underlying char[] in the builder will be used in the resulting String

Woot4Moo Over a year ago

Foreach is less efficient than the standard for loop. Also String uses StringBuilder as its implementation so String+= does not have a negative performance.

JustinKSU Over a year ago

@All I updated to add the length to constructor of StringBuilder. Thanks for the suggestion.

Collectives™ on Stack Overflow

Converting Character[] to String

2 Answers 2

Comments

5 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

5 Comments

Your Answer

Sign up or log in

Post as a guest

Related