3.1 Lesson Outcomes

After completing this lesson, learners will be able to:

• Create and use Strings in Java.
• Concatenate Strings.
• Compare String values.
• Apply String methods.
• Manipulate and format text in Java programs.

3.2 Overview

Strings are reference types used to store and manipulate text in Java applications. Java provides a wide range of String methods used for searching, formatting, comparing, and modifying text.

This lesson introduces learners to practical String operations used in software development.

Strings are important in:

• user input,
• data processing,
• software interfaces,
• and application communication.

Understanding Strings is important because text processing is used in almost every Java application.

PA0801 — Create a String

Strings store text values in Java.

Example String Declaration

Java

String name = “Alice”;

Creating Strings Using new Keyword

Java

String city = new String(“Johannesburg”);

Practical Activity

Learners must:

• create String variables,
• assign text values,
• and display String output.

PA0802 — Concatenate Strings

String concatenation combines multiple text values.

Example Concatenation

Java

String firstName = “John”;

String lastName = “Smith”;

String fullName = firstName + ” ” + lastName;

Example Output

Plain text

John Smith

Practical Activity

Learners must:

• concatenate Strings,
• combine text values,
• and display formatted results.

PA0803 — Use String Methods

Java provides built-in methods for String manipulation.

Common String Methods

Example

Java

String word = “Java”;

System.out.println(word.length());

Practical Activity

Learners must:

• apply String methods,
• manipulate text,
• and display method results.

PA0804 — Compare Strings

Strings can be compared using:

Plain text

equals()

method.

Example

Java

String a = “Java”;

String b = “Java”;

System.out.println(a.equals(b));

Practical Activity

Learners must:

• compare String values,
• test equality,
• and display results.

PA0805 — Search Within Strings

Strings can be searched using built-in methods.

Example contains()

Java

String text = “Welcome to Java”;

System.out.println(text.contains(“Java”));

Example indexOf()

Java

System.out.println(text.indexOf(“Java”));

Practical Activity

Learners must:

• search text,
• identify word positions,
• and display search results.

PA0806 — Remove Spaces and Format Strings

Java provides methods for text formatting.

Example trim()

Java

String text = ” Java “;

System.out.println(text.trim());

Example replace()

String text = “Java”;

System.out.println(text.replace(“Java”, “Python”));

Practical Activity

Learners must:

• remove spaces,
• replace words,
• and format String output.

PA0807 — Convert Between Strings and Numbers

Java allows conversion between Strings and numeric values.

String to Integer

Java

String num = “100”;

int value = Integer.parseInt(num);

Integer to String

Java

int age = 25;

String text = String.valueOf(age);

Practical Activity

Learners must:

• convert Strings to numbers,
• convert numbers to Strings,
• and display results.

PA0808 — Create Complete String Program

Strings are commonly used in software applications.

Example Program

Java

public class StringExample {

public static void main(String[] args) {

String firstName = “John”;
String lastName = “Smith”;

String fullName =
firstName + ” ” + lastName;

System.out.println(fullName);

System.out.println(fullName.toUpperCase());

System.out.println(fullName.length());
}
}

Importance of Strings

Strings support:

• text processing,
• user interaction,
• and application communication.

3.5 Key Notes / Summary

• Strings store text in Java.
• Strings are reference types.
• Strings can be concatenated using +.
• Java provides many String methods.
• equals() compares String values.
• Strings can be searched and formatted.
• Strings are widely used in software applications