Converting 'ArrayList to 'String[]' in Java

Question

How might I convert an ArrayList object to a String[] array in Java?

Answer 1

In Java 8:

String[] strings = list.parallelStream().toArray(String[]::new);

Answer 2

Generics solution to covert any List<Type> to String []:

public static  <T> String[] listToArray(List<T> list) {
    String [] array = new String[list.size()];
    for (int i = 0; i < array.length; i++)
        array[i] = list.get(i).toString();
    return array;
}

Note You must override toString() method.

class Car {
  private String name;
  public Car(String name) {
    this.name = name;
  }
  public String toString() {
    return name;
  }
}
final List<Car> carList = new ArrayList<Car>();
carList.add(new Car("BMW"))
carList.add(new Car("Mercedes"))
carList.add(new Car("Skoda"))
final String[] carArray = listToArray(carList);

Answer 3

You can use Iterator<String> to iterate the elements of the ArrayList<String>:

ArrayList<String> list = new ArrayList<>();
String[] array = new String[list.size()];
int i = 0;
for (Iterator<String> iterator = list.iterator(); iterator.hasNext(); i++) {
    array[i] = iterator.next();
}

Now you can retrive elements from String[] using any Loop.

Answer 4

In Java 11, we can use the Collection.toArray(generator) method. The following code will create a new array of strings:

List<String> list = List.of("one", "two", "three");
String[] array = list.toArray(String[]::new)

from java.base's java.util.Collection.toArray().

Answer 5

An alternative in Java 8:

String[] strings = list.stream().toArray(String[]::new);

Java 11+:

String[] strings = list.toArray(String[]::new);

Answer 6

You can convert List to String array by using this method:

 Object[] stringlist=list.toArray();

The complete example:

ArrayList<String> list=new ArrayList<>();
    list.add("Abc");
    list.add("xyz");

    Object[] stringlist=list.toArray();

    for(int i = 0; i < stringlist.length ; i++)
    {
          Log.wtf("list data:",(String)stringlist[i]);
    }