List<String> strings = Arrays.asList(new String[]{"one", "two", "three"});

This is a list view of the array, the list is partly unmodifiable, you can't add or delete elements. But the time complexity is O(1).

If you want a modifiable a List:

List<String> strings = 
     new ArrayList<String>(Arrays.asList(new String[]{"one", "two", "three"}));

This will copy all elements from the source array into a new list (complexity: O(n))

List<String> list = ..;
String[] array = list.toArray(new String[0]);

For example:

List<String> list = new ArrayList<String>();
//add some stuff
list.add("android");
list.add("apple");
String[] stringArray = list.toArray(new String[0]);

The toArray() method without passing any argument returns Object[]. So you have to pass an array as an argument, which will be filled with the data from the list, and returned. You can pass an empty array as well, but you can also pass an array with the desired size.

Important update: Originally the code above used new String[list.size()]. However, this blogpost reveals that due to JVM optimizations, using new String[0] is better now.

Use this code for that,

import java.util.Arrays;  
import java.util.List;  
import java.util.ArrayList;  

public class StringArrayTest {

   public static void main(String[] args) {  
      String[] words = {"ace", "boom", "crew", "dog", "eon"};  

      List<String> wordList = Arrays.asList(words);  

      for (String e : wordList) {  
         System.out.println(e);  
      }  
   }  
}