CODEWITHSUNDEEP
javaarraylist
Supernovah
Supernovah

Reputation: 2045

Changing String element in an ArrayList<List<String>> is changing both Lists in ArrayList

Here is the code I am using

    ArrayList<List<String>> sentanceParts = new ArrayList<List<String>>();

    int i;

    sentanceParts.add(Arrays.asList(sentance.split("\\s+")));
    sentanceParts.add(sentanceParts.get(0));
    System.out.printf( "%s\n", sentanceParts.get(1).get(0));

    for( i = 0; i < sentanceParts.get(0).size(); i++ ){
        sentanceParts.get(0).set(i, 
        sentanceParts.get(0).get(i).replaceAll( "[^aeiou]+", "" ));
        System.out.printf( "%s:%d\n",
                sentanceParts.get(1).get(i),
                sentanceParts.get(0).get(i).length() );
    }

And it is outputting this

Type a sentance for analysis...
test case
e:1
ae:2

which should be

Type a sentance for analysis...
test case
test:1
case:2

Why is my code not doing this? I thought I was setting the sentanceParts(0) not sentanceParts(1)

Upvotes: 1

Views: 92

Answers (1)

Paul Bellora
Paul Bellora

Reputation: 55223

Because of this line:

sentanceParts.add(sentanceParts.get(0));

sentanceParts is referencing the same List<String> twice.

If you want to add a copy of the List at element 0, then write:

sentanceParts.add(new ArrayList<String>(sentanceParts.get(0)));

Upvotes: 4

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