Java Programmer Skills Programme

3.1 Lesson Outcomes

After completing this lesson, learners will be able to:

Create and use ArrayLists in Java.
Add and remove elements from an ArrayList.
Access and modify ArrayList elements.
Iterate through ArrayLists.
Sort and search ArrayList data.

3.2 Overview

An ArrayList is a dynamic collection in Java that can grow and shrink automatically as elements are added or removed. Unlike arrays, ArrayLists do not require a fixed size during creation.

This lesson introduces learners to practical ArrayList operations used in Java applications.

ArrayLists are important in:

data storage,
collections processing,
enterprise applications,
and object-oriented programming.

Understanding ArrayLists is important because they are widely used in Java software development.

PA0601 — Create an ArrayList

ArrayLists are part of the Java Collections Framework.

Import Statement

Java

import java.util.ArrayList;

Example ArrayList

Java

ArrayList<String> names = new ArrayList<String>();

Practical Activity

Learners must:

import ArrayList,
create ArrayLists,
and use generic data types correctly.

PA0602 — Add Elements to an ArrayList

Elements can be added dynamically to an ArrayList.

Example

Java

names.add(“Alice”);
names.add(“John”);
names.add(“Peter”);

Practical Activity

Learners must:

add elements to an ArrayList,
insert multiple values,
and display results.

PA0603 — Access ArrayList Elements

ArrayList elements are accessed using indexes.

Example

Java

System.out.println(names.get(0));

Practical Activity

Learners must:

access ArrayList elements,
display values,
and use indexes correctly.

PA0604 — Modify ArrayList Elements

Elements in an ArrayList can be updated using the set() method.

Example

Java

names.set(1, “Sarah”);

Practical Activity

Learners must:

modify existing elements,
update values,
and display updated collections.

PA0605 — Remove Elements from an ArrayList

Elements can be removed from an ArrayList dynamically.

Example

Java

names.remove(0);

Remove All Elements

Java

names.clear();

Practical Activity

Learners must:

remove individual elements,
clear collections,
and display updated results.

PA0606 — Determine ArrayList Size

The size of an ArrayList can be determined using the size() method.

Example

Java

System.out.println(names.size());

Practical Activity

Learners must:

determine collection sizes,
display collection counts,
and interpret results.

PA0607 — Iterate Through an ArrayList

ArrayLists can be processed using loops.

Example for Loop

Java

for (int i = 0; i < names.size(); i++) {

System.out.println(names.get(i));
}

Example Enhanced for Loop

Java

for (String name : names) {

System.out.println(name);
}

Practical Activity

Learners must:

iterate through ArrayLists,
use loops correctly,
and display collection data.

PA0608 — Sort an ArrayList

ArrayLists can be sorted using utility methods.

Import Collections

Java

import java.util.Collections;

Example Sorting

Java

Collections.sort(names);

Practical Activity

Learners must:

sort ArrayLists,
display sorted values,
and compare results.

PA0609 — Search ArrayList Elements

ArrayLists support searching and value checking.

Example

Java

names.contains(“Alice”);

Practical Activity

Learners must:

search collections,
check for existing values,
and display results.

PA0610 — Create Complete ArrayList Program

ArrayLists can be combined into complete Java applications.

Example Program

Java

import java.util.ArrayList;
import java.util.Collections;

public class ArrayListExample {

public static void main(String[] args) {

ArrayList<String> names =
new ArrayList<String>();

names.add(“Alice”);
names.add(“John”);
names.add(“Peter”);

Collections.sort(names);

for (String name : names) {

System.out.println(name);
}
}
}

Importance of ArrayLists

ArrayLists support:

dynamic data storage,
flexible collections,
and scalable Java applications.

3.5 Key Notes / Summary

ArrayLists are dynamic collections in Java.
ArrayLists automatically resize.
Elements are added using add().
Elements are accessed using get().
Elements are modified using set().
Elements are removed using remove().
Collections.sort() sorts ArrayList elements.