- Java Introduction
- Overview
- History and Evolution of Java
- Key Milestones
- Features of Java
- Java Development Kit (JDK) and Java Runtime Environment (JRE)
- Setting up the Java Development Environment
- Writing a Simple Java Program
- Understanding the Structure of a Java Program
- Java Fundamentals
- Variables and Data Types
- int
- float
- double
- char
- boolean
- Type Casting and Type Conversion in Java
- Type Casting
- Implicit casting (Widening Conversion)
- Explicit Casting (Narrowing Conversion)
- Type Conversion
- Implicit Conversion
- Explicit Conversion
- Important Points
- Operators
- Relational Operators
- Unary Operators
- Conditional Statements
- if Statement
- if-else Statement
- switch Statement
- Looping Statements
- for Loop
- while Loop
- do-while Loop
- Break and Continue Statements
- Arithmetic Operators
- Logical Operators
- Assignment Operators
- Java OOPS Concepts
- Classes and Objects
- Defining a Class
- Creating Objects
- Constructors
- This Keyword
- Methods
- Defining Methods
- Method Overloading
- Static Methods
- Encapsulation
- Access Modifiers
- Getters and Setters
- Inheritance
- Extending Classes
- Method Overriding
- super Keyword
- Example: Inheritance in an Animal Hierarchy
- Polymorphism
- Compile-Time Polymorphism (Method Overloading)
- Runtime Polymorphism (Method Overriding)
- Abstraction
- Abstract Classes and Methods
- Interfaces
- Java Advanced Concepts
- Arrays and Strings
- Single-Dimensional Arrays
- Multi-Dimensional Arrays
- The String Class and String Operations
- Exception Handling
- Types of Exceptions
- Try-Catch Block
- Finally Block
- Throw and Throws Keyword
- Custom Exceptions
- File I/O
- The File Class
- Handling File Exceptions
- Reading from a File
- Java Collections Framework
- Introduction to Collections
- Overview of the Collections Framework
- List Interface
- Set Interface
- Map Interface
- ArrayList and LinkedList
- ArrayList
- Creating and Using ArrayLists
- LinkedList
- Creating and Using LinkedLists
- HashSet and TreeSet
- HashSet
- Creating and Using HashSet
- TreeSet
- Creating and Using TreeSet
- HashMap and TreeMap
- HashMap
- Creating and Using HashMap
- TreeMap
- Creating and Using TreeMap
- Java GUI Programming
- Introduction to GUI Programming
- Overview of AWT and Swing
- Creating a Simple GUI Application Using Swing
- Components and Event Handling
- Common Swing Components
- Example: Creating a Simple GUI with Event Handling
- Java Project Development
- Developing a console-based a to-do list manager application
- Further Learning and Development
- Next Steps
- Conclusion
The String Class and String Operations
The String Class and String Operations in Java
Creating and manipulating strings in Java is accomplished via the usage of the String class. Due to the fact that strings are immutable, it is not possible to alter their values once they have been produced.
| public class StringOperations { public static void main(String[] args) { // Declare and initialize a string String message = "Hello, World!"; // String length int length = message.length(); System.out.println("Length: " + length); // Output: 13 // Character at a specific index char charAt = message.charAt(0); System.out.println("Character at index 0: " + charAt); // Output: H // Substring String substring = message.substring(7, 12); System.out.println("Substring: " + substring); // Output: World // String concatenation String greeting = "Hello"; String name = "Alice"; String fullGreeting = greeting + ", " + name + "!"; System.out.println("Concatenated String: " + fullGreeting); // Output: Hello, Alice! // String comparison boolean isEqual = greeting.equals("Hello"); System.out.println("Is equal: " + isEqual); // Output: true // String to upper case String upperCase = message.toUpperCase(); System.out.println("Upper case: " + upperCase); // Output: HELLO, WORLD! // String to lower case String lowerCase = message.toLowerCase(); System.out.println("Lower case: " + lowerCase); // Output: hello, world! // Replace characters String replaced = message.replace('o', 'a'); System.out.println("Replaced: " + replaced); // Output: Hella, Warld! } } |
There is a declaration and initialization of the message string.
A number of string operations are presented, including:
- The string's length is returned by the length() function.
- The character that is located at the supplied index is returned by the charAt(int index) function.
- The function substring(int beginIndex, int endIndex) returns a substring that is derived from the range that was supplied.
- Concatenation of strings with the use of the + sign.
- equals(Object anObject) is a function that verifies the equality of two strings.
- toUpperCase() turns the string to uppercase.
- The toLowerCase() function changes the string to lowercase letters.
- It is possible to replace instances of a character with another character by using the replace(char oldChar, char newChar statement.
