Extract String arrays from List

Question

Developing a Java Android App but this is a straight up Java question i think.

I have List declared as follows;

List list= new ArrayList<String[]>();

I want to extract each String [] in a loop;

for(int i=0; i < list.size(); i++) {
   //get each String[]
   String[] teamDetails = (String[])list.get(i);
}

This errors, I am guessing it just doesn't like me casting the String[] like this.

Can anyone suggest a way to extract the String[] from my List?

my bad i changed code last sec for clarity, my effort failed :) editing now — Fearghal, Sep 08 '15 at 10:20
What is the error? This should work (I'm guessing you missed `()` in the `size` call). — Tunaki, Sep 08 '15 at 10:21
your declaration should be `List list= new ArrayList<>();`. This way you wouldn't need the cast — Blackbelt, Sep 08 '15 at 10:21
Don't use rawtypes. Ever. If you don't know what a rawtype is, this read about Java generics before "dev'ing" any apps. — Boris the Spider, Sep 08 '15 at 10:24
Possible duplicate of [What is a raw type and why shouldn't we use it?](http://stackoverflow.com/questions/2770321/what-is-a-raw-type-and-why-shouldnt-we-use-it) — Tom, Sep 21 '16 at 11:10

OldCurmudgeon · Accepted Answer · 2015-09-08T12:45:26.377

7

Use a List<String[]> and you can use the more up-to-date looping construct:

    List<String[]> list = new ArrayList<String[]>();

    //I want to extract each String[] in a loop;
    for ( String[] teamDetails : list) {

    }

    // To extract a specific one.
    String[] third = list.get(2);

edited Sep 08 '15 at 12:45

answered Sep 08 '15 at 10:24

OldCurmudgeon

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this is a go-er, now a confession. The loop is artificially put there for the purpose of the question. How would i reach into each String[] in list if just given a integer of the appropriate array? – Fearghal Sep 08 '15 at 10:30
@Fearghal exactly as you think: `final String[] array = list.get(i)`. – Boris the Spider Sep 08 '15 at 10:32
@Fearghal - In the same way you already do - `list.get(index)` - just make sure you declare as `List`. – OldCurmudgeon Sep 08 '15 at 10:32
I got an error. maybe i have made a mistake in something above. java.util.ArrayList cannot be cast to java.lang.String[] – Fearghal Sep 08 '15 at 12:41
@Fearghal - Added a further example for how to get a specific one. – OldCurmudgeon Sep 08 '15 at 12:45
See my updated question and prev reply to you - this causes an error – Fearghal Sep 08 '15 at 12:46
@Fearghal - Check what line the error is on - it won't be on the assignment as that is correct. – OldCurmudgeon Sep 08 '15 at 12:48
unfortunately its at the line String[] teamDetails = list.get(i); – Fearghal Sep 08 '15 at 12:50
@Fearghal - That seems unlikely. My code compiles fine. – OldCurmudgeon Sep 08 '15 at 13:06
Im not 100% but you are right, i dont think its your solution. Il mark it as answer. Thx a mill for your help, appreciated. – Fearghal Sep 08 '15 at 13:29

PKuhn · Answer 2 · 2015-09-08T10:26:56.463

1

Try declaring the list this way

List<String[]> list = new ArrayList<>();

for(int i = 0; i < list.size(); i++) {
    //get each String[]
    String[] teamDetails = list.get(i);
}

Moreover the call of your size function was wrong you need to add the brackets

edited Sep 08 '15 at 10:26

answered Sep 08 '15 at 10:24

PKuhn

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You don't need to cast. – Boris the Spider Sep 08 '15 at 10:24
the cast is not necessary, the declaration will solve Fearghal's problem. – Jörn Buitink Sep 08 '15 at 10:25

score 0 · Answer 3 · answered Sep 08 '15 at 10:22

    /*ArrayList to Array Conversion */
            String array[] = new String[arrlist.size()];              
            for(int j =0;j<arrlist.size();j++){
              array[j] = arrlist.get(j);
            }

//OR
/*ArrayList to Array Conversion */
        String frnames[]=friendsnames.toArray(new String[friendsnames.size()]);

score 0 · Answer 4 · answered Sep 08 '15 at 10:25

0

In for loop change list.size to list.size()

And it works fine Check this https://ideone.com/jyVd0x

answered Sep 08 '15 at 10:25

Manoj Kumar

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score 0 · Answer 5 · answered Sep 21 '16 at 11:15

First of all you need to change declaration from List list= new ArrayList<String[]>(); to List<String[]> list = new ArrayList();

After that you can do something like

String[] temp =  new String[list.size];

for(int i=0;i<list.size();i++)`
{
temp[i] = list.get(i);
}

Extract String arrays from List

5 Answers5