Trying to convert an ArrayList to String

Question

I have the following code:

ArrayList<String> idattributes=new ArrayList();
idattributes.add("7");
idattributes.add("10");
idattributes.add("12");

I'm trying to convert it to a string like this:

String listString = "";
for (String s : idattributes) {
      listString += s + "\t";
} 
System.out.println(listString);

I get: "7   10  12  "

How could I remove those multiple spaces? I just want a string "7 10 12" Any other good way to convert idattributes to a String? Thanks

Those aren't "multiple spaces;" they're tabs, which is exactly what `"\t"` tells the code to do. Why not use `List#toString()`? — Matt Ball, May 31 '13 at 18:06
"\t" is a tab. if you want just a simple space, say so: listString += s + " "; — Dmitry B., May 31 '13 at 18:06
If you want a single space between items, then use `" "` instead of `"\t"`. If you mean the spaces at the end, `trim()`. — thegrinner, May 31 '13 at 18:07

score 1 · Answer 1 · answered May 31 '13 at 18:07

Sometimes it pays not to try to be too smart and use an inefficient trim() :)

String listString = "";
for (String s : idattributes) {
    listString += s + " ";
} 
listString = listString.trim();

Unless you meant to have the tab in there, in which case

listString += s + "\t"

is fine, but the trim() is still required.

score 0 · Answer 2 · answered May 31 '13 at 18:10

0

to get "7 10 12" code has to be like

String listString = "";
for (String s : idattributes) {
  listString += s + " ";
} 
System.out.println(listString.trim());

answered May 31 '13 at 18:10

twid

6,368
4
32
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score 0 · Answer 3 · answered May 31 '13 at 18:11

0

You have a couple of options:

String listString = "";
for (String s : idattributes) {
      listString += s + " ";
} 
listString = listString.trim();

System.out.println(listString);

Or,

System.out.println(idattributes.toString());

answered May 31 '13 at 18:11

bn.

7,739
7
39
54

score 0 · Answer 4 · answered May 31 '13 at 18:11

First of all, replace the "\t" by " ", then choose between :

for (int i = 0 ; i < idattributes.size() ; i++)
{
    listString += itattributes.get(i);
    if (i != idattributes.size() - 1)
        listString += " ";
}

and :

your code, followed by listString.trim()

score 0 · Answer 5 · answered May 31 '13 at 18:11

0

Another good way is to use Guava's Joiner class.

 String listString = Joiner.on(" ").join( idattributes );

answered May 31 '13 at 18:11

Andy Thomas

84,978
11
107
151

score 0 · Answer 6 · edited May 23 '17 at 11:57

0

It's a good idea to use StringBuilder instead of String. You can find more info here

StringBuilder sb = new StringBuilder();
for (String s : idattributes) {
      sb.append(s).append(" ");
} 
String listString = sb.toString().trim()l
System.out.println(listString);

Also you can use the Joiner of the Guava lib.

String listString = Joiner.on(" ").join( idattributes ).trim();

edited May 23 '17 at 11:57

Community

1
1

answered May 31 '13 at 18:16

Petros Tsialiamanis

2,718
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35

Trying to convert an ArrayList to String

6 Answers6