Convert ArrayList Contents to String with Commas

Question

Hello fellow programmers,

In my app I just deserialized an ArrayList from a text file and now I have an ArrayList with Strings. For design purposes I want to put the contents of the ArrayList into one organized string with comas and spaces.

I made an attempt at it but he app forcecloses and the LogCat pinpoints the error to this code:

FYI: OptionsText is an empty string and ListOptions is the ArrayList with the strings.

public void getOptionsText(){
        int i;
        OptionsText=ListOptions.get(1);
        for(i=2; i<ListOptions.size(); i++){
            OptionsText = OptionsText + ", " + ListOptions.get(i);
        }
        Options.setText(OptionsText);
    }

Matt Ball · Accepted Answer · 2013-07-03 23:50:04Z

1

Just use ArrayList#toString():

public void getOptionsText() {
    String OptionsText = ListOptions.toString();
    Options.setText(OptionsText.substring(1, OptionsText.length-1);
}

answered Jul 3, 2013 at 23:50

Matt Ball

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2 Comments

Steve Kuo Over a year ago

This assumes ListOptions is an ArrayList. What if ListOptions is a List? Since the List implementation is unknown ("program to the interface"), it would be better to use Arrays.toString.

Matt Ball Over a year ago

@SteveKuo not really. It assumes that ListOptions is an AbstractCollection, an abstract class which pretty much every Java SE collection implementation inherits. Sure, a joiner (Guava/Apache Commons/other) would work; so would a hand-written method. Show me an existing library implementation with a different toString() output format; then, we'll talk.

nmanandhan · Accepted Answer · 2013-07-03 23:54:10Z

0

can you please try this...check if list is not null...

list.toString().replace("[", "").replace("]", "");

answered Jul 3, 2013 at 23:54

nmanandhan

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1 Comment

Matt Ball Over a year ago

This is actually worse than my answer, both in performance and correctness. What if one of the elements of the list's string form contains '[' or ']'?

JHS · Accepted Answer · 2013-07-04 00:01:25Z

0

Other than the other answers given by fellow SO users, you can also use the join method from the StringUtils class from org.apache.commons.lang.

OR

The join method from the Joiner class from com.google.common.base

answered Jul 4, 2013 at 0:01

JHS

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