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javaarrays
kaydanzie
kaydanzie

Reputation: 386

Java, How to split elements of a list?

I'm trying to split the individual elements of a String[] array. The array looks like 

{"0 1 0 1", "0 0 1 1", "1 1 0 1",...}.

I want to split each element by the regex " ", a single space. If I do that, does it make the one element "0 1 0 1" into 4 elements "0", "1", "0", and "1"? Here is my code that adds the elements to the list (reading from a text file with rows of 4 digit numbers separated by spaces) but the part using the "split" method is not working. It is not having any affect on the array produced. The name of the String[] array is "splitted".

    int j=0;
    String thisLine = null;

        while(((thisLine=readThrough.readLine()) != null) && j<3){
             splitted[j]= thisLine;
             splitted[j].split(" ");
             j++;
        }

Upvotes: 3

Views: 17319

Answers (2)

&#211;scar L&#243;pez
&#211;scar L&#243;pez

Reputation: 235984

The split() method doesn't modify the string in-place, you have to assign the returned String[] to something. If you want to process all the values, try something like this:

 String[] array = {"0 1 0 1", "0 0 1 1", "1 1 0 1"};
 List<String> answer = new ArrayList<String>();

 for (String str : array)
    for (String s : str.split(" "))
        answer.add(s);

After the loop runs, answer will contain the following string values:

[0, 1, 0, 1, 0, 0, 1, 1, 1, 1, 0, 1]

Optionally, if you need the output result as an array of strings you can do this:

String[] output = answer.toArray(new String[answer.size()]);

Upvotes: 4

camickr
camickr

Reputation: 324098

 splitted[j].split(" ");

This method returns an Array contain the 4 values. You didn't assign the result of the split() method to any variable.

In any case you can't just add 4 values to an single Array index (which is what it looks like you are trying to do).

You would need code something like:

String[] values = thisLine.split(" " );

for (int i = 0; i < values.length; i++)
    splitted[j++] = values[i];

Of course don't forget to make your Array large enough to hove all the values. The size will need to be 4 x rows of data.

Upvotes: 0

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