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);
 }

• driangle: why can't you do words.add(...) 1000 times?
• Aaron Kurtzhals: It is hard to understand the essence of your question. What is the problem with calling words.add() 1000 times?
• Steve Kuo: 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.
• A--C: possible duplicate of Convert ArrayList<String> to String []

Answer 1

You can use

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

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Relevant Documentation

• List#toArray(T[])

Answer 2

words.toArray() should work fine.

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

• arshajii: I think this will cause a ClassCastException.

Answer 3

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

Collection toArray example

Answer 4

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