Java: Increase the size of an array list

Last update on May 21 2025 12:47:40 (UTC/GMT +8 hours)

20. Increase ArrayList Capacity

Write a Java program to increase an array list size.

Pictorial Presentation:

Sample Solution:-

Java Code:

import java.util.ArrayList;
import java.util.Collections;
  public class Exercise20 {
  public static void main(String[] args) {
          ArrayList<String> c1= new ArrayList<String>(3);
          c1.add("Red");
          c1.add("Green");
          c1.add("Black");
          System.out.println("Original array list: " + c1);
          //Increase capacity to 6
          c1.ensureCapacity(6);
          c1.add("White");
          c1.add("Pink");
          c1.add("Yellow");
          System.out.println("New array list: " + c1);
   }
}

Sample Output:

Original array list: [Red, Green, Black]                               
New array list: [Red, Green, Black, White, Pink, Yellow]

Flowchart:

For more Practice: Solve these Related Problems:

• Write a Java program to ensure an ArrayList has a minimum capacity using ensureCapacity() and then add a large number of elements.
• Write a Java program to dynamically increase the capacity of an ArrayList and observe the growth pattern.
• Write a Java program to implement a custom dynamic array that mimics ArrayList behavior including capacity increase.
• Write a Java program to test the impact of calling ensureCapacity() on an ArrayList before bulk insertion.

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