String Array to String

Question

I am trying to take an arbitrary-length String[] and print it out to a String, preferably with field separators. Right now I have:

String[] start = {"first", "second", "third"}; //[] to convert
String cC = "";
String finish = ""; // Final String
String cC1 = "";
{
    for (int i = 0; i < puts.length; i++) {
        cC = puts[i] + ", ";
        cC1 = (finish + cC);
        finish = cC1;
    }
}

But for some reason it is only returning the "second" value. How can I make it properly concatenate the values?

Also, could I simplify the code by using finish += cC? Thanks.

Should `puts` be `start`? Also, you should be appending to the same element and finally printing that element. — Sotirios Delimanolis, Aug 02 '13 at 19:24
Thanks, sorry, I was changing names when I copied it from my program. — Lableable, Aug 02 '13 at 19:26

Steve P. · Accepted Answer · 2013-08-02T19:30:48.913

5

String[] start = {"first", "second", "third"};
String addedTogether = Arrays.toString(start);

System.out.println(addedTogether);
//prints [first, second, third]

edited Aug 02 '13 at 19:30

answered Aug 02 '13 at 19:25

Steve P.

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If you want separators, take a look at http://stackoverflow.com/questions/187676/java-equivalents-of-c-sharp-string-format-and-string-join – Ameen Aug 02 '13 at 19:26
That'll do it. Thanks Steve and Ameen! – Lableable Aug 02 '13 at 19:30
Yes, but only because the noob timers don't allow me to accept an answer for ~20 mins. Works now. – Lableable Aug 02 '13 at 19:49

Manolis Proimakis · Answer 2 · 2013-08-02T19:57:38.167

1

If You want to append to a string you should use += e.g.

String[] start = {"first", "second", "third"};
String cc = "";
String separator = ",";

for (int i = 0; i < start.length; i++) {
    cc += start[i];
    //Not Add , if it is the last element.
    if(i!=start.length-1){
       cc+=separator;
    }
}

etc.

with your way you are setting the last value to finish.

edited Aug 02 '13 at 19:57

answered Aug 02 '13 at 19:27

Manolis Proimakis

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No, concatenation is a bad idea. StringBuilder should be generally used. +1 anyway as valid/ – nanofarad Aug 02 '13 at 19:39
@hexafraction Agreed, concatenation is a bad idea, but nonetheless, why are you, @ManosProm, doing `"One" + ","` instead of `"One,"`? It unnecessarily makes an additional `StringBuilder`. – Steve P. Aug 02 '13 at 19:48
oh yes, i thought of adding the array and i added "one" , "two" honest mistake and i will edit the answer to fix this. – Manolis Proimakis Aug 02 '13 at 19:50
1

@hexafraction Generally i know that concatenation is a bad idea. But his problem was that he wasn't using it the right way and instead of giving him a whole new approach, it is better to correct the mistakes :) – Manolis Proimakis Aug 02 '13 at 20:01

score 0 · Answer 3 · edited May 23 '17 at 12:28

0

It is a very bad idea to concatenate Strings using += operator. It is always better to construct StringBuilder object and append all the values to it. And lastly call toString() on the StringBuilder object.

Take a look at this link to understand the performance hit associated with using + operator for string concatenation.
http://blog.eyallupu.com/2010/09/under-hood-of-java-strings.html
How Java do the string concatenation using "+"?

edited May 23 '17 at 12:28

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answered Aug 02 '13 at 19:27

Ankur Shanbhag

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I believe you, but could you please elaborate why "it is a very bad idea to concatenate Strings using += operator?" – Lableable Aug 02 '13 at 19:32
please refer the links that I have added in my answer. – Ankur Shanbhag Aug 02 '13 at 19:33

score 0 · Answer 4 · answered Aug 02 '13 at 19:28

String[] start = {"first", "second", "third"}; //[] to convert
String finish = ""; // Final String
{
    for (int i = 0; i < starts.length; i++) {
        finish = finish + start[i] + ", ";
    }
}

(If you wanted to do all this manually for some reason...)

score 0 · Answer 5 · edited May 23 '17 at 12:11

0

Check out -- Java equivalents of C# String.Format() and String.Join()

That provides a string.join method, as well as some reading on useful string utility methods.

edited May 23 '17 at 12:11

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answered Aug 02 '13 at 19:36

Jon La Marr

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String Array to String

5 Answers5