Increases the capacity of an ArrayList

You can increase the capacity of an ArrayList object manually by calling ensureCapacity( ). By increasing its capacity once, at the start, you can prevent several reallocations later.

void ensureCapacity(int minCapacity)

Increases the capacity of this ArrayList instance, if necessary, to ensure that it can hold at least the number of elements specified by the minimum capacity argument.

import java.util.ArrayList;

public class Main {
  public static void main(String args[]) {
    ArrayList<String> al = new ArrayList<String>();

    al.add("C");
    al.add("A");
    al.add("E");
    al.add("java2s.com");
    al.add("D");
    al.add("F");
    al.add(1, "java2s.com");

    System.out.println(al);
    System.out.println(al.size());
    al.ensureCapacity(100);
    System.out.println(al.size());

  }

}
  

The output:

[C, java2s.com, A, E, java2s.com, D, F]
7
7

1. ArrayList Class
2. Create ArrayList object
3. Add to ArrayList
4. Clear an ArrayList
5. Shallow copy of current ArrayList
6. If contain a certain object
7. Increases the capacity of an ArrayList
8. Get/Replace element by index
9. Get object for index
10. Remove from ArrayList
11. Get the size and trim to size
12. If ArrayList is empty
13. Convert ArrayList to array