Adding string arrays to a 2d String array through iteration

Question

Am trying to create an array which holds the String arrays created from a utilising the String.split() method on a string which is input through a loop.

int N = in.nextInt();
String [][] defibDetails = new String[N][];
in.nextLine();
for (int i = 0; i < N; i++) {
    String DEFIB = in.nextLine();
    String [] details = DEFIB.split(";");
    defibDetails[i][]=details;
}
System.out.println(defibDetails[0][0]);

I would like the System.out to be the substring of DEFIB before the first ; where loop counter i = 0. Thanks for any thoughts.

Do you know the size of your total input? String arrays need to be given a predetermined size. Have you thought of using lists. List<List<String>> details = new ArrayList<>(); Is the 'in' object in your code the Scanner class? — Adrian359
– Adrian359, Commented Jul 20, 2016 at 16:05
Read the error message you get from the compiler, fix the error (it should be defibDetails[i] = details;, and you will have the expected behavior. You can't expect a program to do something if it doesn't even compile. — JB Nizet
– JB Nizet, Commented Jul 20, 2016 at 16:13
Unfortunately the length varies. Am open to using any form of collection but quite new to Java and don't know the best for a given application. Looked at lists but couldn't work out the 2d syntax for getting the value back. Would it be list.get(0).list.get(0) ? — GregB
– GregB, Commented Jul 20, 2016 at 16:23
nizet the code is actually for a 2d array so I don't think I want to do that unless you can expand on why? — GregB
– GregB, Commented Jul 20, 2016 at 16:25
No. list.get(0) returns a List<String>. Sna dyou can call get(0) on a List<String> to get its first element. So it's list.get(0).get(0). But you can use two instructions to make it clearer: List<String> firstList = list.get(0); String firstString = firstList.get(0); — JB Nizet
– JB Nizet, Commented Jul 20, 2016 at 16:27

B-GangsteR · Accepted Answer · 2016-07-20 16:12:31Z

1

The error is here: defibDetails[i][] ; it should be like this: defibDetails[i] You've got a two dimensional array, so fist dimension is particular array of "array of arrays". Second is particular element of this array. So defibDetails[i] means array #i, defibDetails[i][j] means element j in array i.

int N = in.nextInt();
String [][] defibDetails = new String[N][];
in.nextLine();
for (int i = 0; i < N; i++) {
    String DEFIB = in.nextLine();
    String [] details = DEFIB.split(";");
    defibDetails[i]=details; // <<<<<<<<
}
System.out.println(defibDetails[0][0]);

http://ideone.com/Dr9Aci

answered Jul 20, 2016 at 16:12

B-GangsteR

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1 Comment

GregB Over a year ago

Thank you. Thought since it was 2d needed to use constant 2d notation. Has fixed the issue.

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