ArrayList to Array

Question

How do I convert this ArrayList's value into an array? So it can look like,

String[] textfile = ... ;

The values are Strings (words in the text file), and there are more than a 1000 words. In this case I cannot do the, words.add("") 1000 times. How can I then put this list into an array?

    public static void main(String[]args) throws IOException
    {
        Scanner scan = new Scanner(System.in);
        String stringSearch = scan.nextLine();

        List<String> words = new ArrayList<String>(); //convert to array
        BufferedReader reader = new BufferedReader(new FileReader("File1.txt"));

        String line;
        while ((line = reader.readLine()) != null) {                
            words.add(line);
        }

It is hard to understand the essence of your question. What is the problem with calling words.add() 1000 times? — Aaron Kurtzhals
– Aaron Kurtzhals, Commented Jan 8, 2013 at 20:53
I would start by asking why you want an array of Strings? Unless you have an API that only takes arrays, you can use List in place of an array. Especially given that ArrayList is backed by an array. — Steve Kuo
– Steve Kuo, Commented Jan 8, 2013 at 21:02
possible duplicate of Convert ArrayList<String> to String [] — A--C
– A--C, Commented Jan 8, 2013 at 22:18

arshajii · Accepted Answer · 2013-01-08 20:50:24Z

13

You can use

String[] textfile = words.toArray(new String[words.size()]);

Relevant Documentation

List#toArray(T[])

answered Jan 8, 2013 at 20:50

arshajii

130k26 gold badges246 silver badges293 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Juvanis · Accepted Answer · 2013-01-08 20:50:24Z

0

words.toArray() should work fine.

List<String> words = new ArrayList<String>();
String[] wordsArray = (String[]) words.toArray();

answered Jan 8, 2013 at 20:50

Juvanis

26k5 gold badges74 silver badges88 bronze badges

1 Comment

arshajii Over a year ago

I think this will cause a ClassCastException.

jethroo · Accepted Answer · 2013-01-08 20:51:53Z

0

you can use the toArray method of Collection such as shown here

Collection toArray example

answered Jan 8, 2013 at 20:51

jethroo

2,1242 gold badges19 silver badges32 bronze badges

Comments

Avinash T. · Accepted Answer · 2013-01-08 20:52:18Z

0

List<String> words = new ArrayList<String>();
words.add("w1");
words.add("w2");
String[] textfile = new String[words.size()];
textfile = words.toArray(textfile);

answered Jan 8, 2013 at 20:52

Avinash T.

2,3692 gold badges16 silver badges23 bronze badges

Collectives™ on Stack Overflow

ArrayList to Array

4 Answers 4

Comments

1 Comment

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

4 Answers 4

Comments

1 Comment

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related