What is a Java String?

Table of Contents

• Introduction
• Characteristics of Java Strings
• Creating Strings in Java
  • Using String Literals
  • Using the new Keyword
  • Example of Creating Strings
    • Output:
• Common String Operations
  • 1. Length of a String
  • 2. Concatenation
  • 3. Substring
  • 4. String Comparison
  • 5. String Formatting
• Practical Examples
  • Example 1: Counting Vowels in a String
    • Output:
  • Example 2: Reversing a String
    • Output:
• Conclusion

Introduction

In Java, a String is a sequence of characters used to represent textual data. Strings are one of the most commonly used data types in Java programming, and they are vital for various operations, such as displaying messages, processing user input, and manipulating text. Understanding how to create and manipulate Strings is essential for any Java programmer.

Characteristics of Java Strings

1. Immutable: Once a String object is created, its value cannot be changed. Any operation that modifies a String results in a new String object being created.
2. Defined in the String Class: The String class in Java provides various methods for creating and manipulating Strings. It is part of the java.lang package.
3. Zero-Based Indexing: Characters in a String can be accessed using zero-based indexing, where the first character is at index 0.

Creating Strings in Java

Using String Literals

You can create a String using string literals, which are enclosed in double quotes. For example:

Using the new Keyword

Strings can also be created using the new keyword:

Example of Creating Strings

Here’s an example showing both methods of creating Strings:

Output:

Common String Operations

1. Length of a String

You can find the length of a String using the length() method:

2. Concatenation

Strings can be concatenated using the + operator or the concat() method:

3. Substring

To extract a substring, use the substring() method:

4. String Comparison

You can compare Strings using equals() and equalsIgnoreCase() methods:

5. String Formatting

Strings can be formatted using the String.format() method:

Practical Examples

Example 1: Counting Vowels in a String

Here's a simple program to count the number of vowels in a given String:

Output:

Example 2: Reversing a String

Here's a simple program to reverse a String:

Output:

Conclusion

Strings in Java are essential for handling text data. They are immutable, defined in the String class, and provide a variety of methods for manipulation. Understanding how to create, modify, and perform operations on Strings is crucial for effective Java programming. With the practical examples provided, you should now have a solid foundation to work with Strings in your Java applications.