Strings in Java

Almost every real-world application works with text. Names, emails, messages, addresses, search queries — all of these are handled as text.

In Java, text data is represented using the String class. Understanding strings is essential for building meaningful applications.

What Is a String?

A String is a sequence of characters. In Java, strings are not primitive data types — they are objects created from the String class.

This means strings come with powerful built-in methods that help manipulate and analyze text easily.

Creating Strings in Java

There are two common ways to create strings in Java. Both store text, but they work slightly differently internally.

public class StringCreation {

    public static void main(String[] args) {

        String name1 = "Java";
        String name2 = new String("Programming");

        System.out.println(name1);
        System.out.println(name2);
    }
}

For most applications, using double quotes is recommended. It is simpler and more memory-efficient.

Why Strings Are Immutable

In Java, strings are immutable. This means once a string is created, its value cannot be changed.

When you modify a string, Java actually creates a new string in memory. This design improves security and performance.

This behavior is especially important in multi-threaded and large-scale applications.

Common String Operations

Java provides many useful methods to work with strings. These methods help extract, compare, and modify text.

• length() – returns the length of a string
• toUpperCase() – converts text to uppercase
• toLowerCase() – converts text to lowercase
• charAt() – gets a character at a specific position
• equals() – compares string values

Example: Working with String Methods

Let’s look at a practical example that performs common string operations.

public class StringMethods {

    public static void main(String[] args) {

        String message = "Welcome to Java";

        System.out.println(message.length());
        System.out.println(message.toUpperCase());
        System.out.println(message.toLowerCase());
        System.out.println(message.charAt(0));
        System.out.println(message.equals("Welcome to Java"));
    }
}

These methods make it easy to handle text without writing complex logic.

Comparing Strings Correctly

One common mistake beginners make is comparing strings using ==.

The == operator compares memory references, not actual text values.

To compare content, always use equals().

Real-World Use of Strings

Strings are used everywhere in real applications:

• User input and validation
• Form data and messages
• File paths and URLs
• Database queries

A strong understanding of strings is critical for building real Java systems.

What You Learned in This Lesson

• What strings are in Java
• How to create strings
• Why strings are immutable
• How to use common string methods
• How to compare strings correctly

In the next lesson, you will learn about arrays, which allow Java programs to store multiple values together.