Java-Methods
A method in Java is a block of code within a class that performs a specific task when called. Methods can accept parameters, execute instructions, and optionally return a result. They help organize code into reusable, manageable units, making programs more modular, readable, and easier to maintain.
Syntax:
access_modifier return_type methodName(parameters) {// Method body}
Example:
public void helloWorld(int a) { // code}Parameters in Methods
A parameter is a variable listed inside the parentheses in the method definition. It acts as a placeholder for the value you want to pass to the method.
Example:
A parameter is a variable listed inside the parentheses in the method definition. It acts as a placeholder for the value you want to pass to the method.
Example:
public class Main { public static void main(String[] args) { String name = "Quipo House"; message(name); // 'name' is the argument } static void message(String name) { // 'name' is the parameter System.out.println(name); }}Output:
Quipo HouseArguments
An argument is the actual value that gets passed to the method’s parameter when the method is called.
Example:
An argument is the actual value that gets passed to the method’s parameter when the method is called.
Example:
public class Main { public static void main(String[] args) { message("HELLO QUIPO HOUSE"); // "HELLO QUIPO HOUSE" is the argument } static void message(String message) { System.out.println(message); }}Output:
HELLO QUIPO HOUSETypes of Methods in Java
1. Predefined Methods (Built-in Methods)
These are methods already provided by Java libraries. You use them without having to define their logic.
Example:
1. Predefined Methods (Built-in Methods)
These are methods already provided by Java libraries. You use them without having to define their logic.
Example:
public class Main { public static void main(String[] args) { String name = "QUIPO HOUSE"; System.out.println(name.toLowerCase()); // toLowerCase() is a predefined method }}Other examples include Math.max(), Math.min(), System.out.println(), etc.
2. User-Defined Methods
These are methods written by the programmer to perform specific tasks.
Example:
These are methods written by the programmer to perform specific tasks.
Example:
public class Main { public static void main(String[] args) { String name = "Quipo House"; message(name); }
static void message(String name) { System.out.println(name); }}Output:
Quipo House3. Static Methods
A static method belongs to the class rather than to any specific object. You can call a static method directly using the class name or from another static method.
Example:
A static method belongs to the class rather than to any specific object. You can call a static method directly using the class name or from another static method.
Example:
public class Main { public static void main(String[] args) { String name = "Quipo House"; message(name); // Direct call Main.message(name); // Call using class name Main m = new Main(); m.message(name); // Call using object }
static void message(String name) { System.out.println(name); }}Output:
Quipo House
Quipo House
Quipo House4. Instance Methods
Also known as non-static methods, these require you to create an object of the class to call them.
Example:
Also known as non-static methods, these require you to create an object of the class to call them.
Example:
public class Main { public static void main(String[] args) { InstanceMethod obj = new InstanceMethod(); obj.displayMessage("HELLO QUIPO HOUSE"); }}
class InstanceMethod { public void displayMessage(String message) { System.out.println(message); }}Output:
HELLO QUIPO HOUSE5. Abstract Methods
An abstract method is declared without a body and is marked with the abstract keyword. It must be implemented by subclasses of the abstract class.
Syntax:
An abstract method is declared without a body and is marked with the abstract keyword. It must be implemented by subclasses of the abstract class.
Syntax:
abstract void methodName();Example:
abstract class Message { abstract void greet();
void displayName() { System.out.print("QUIPO HOUSE"); }}
class Greet extends Message { void greet() { System.out.print("HELLO "); }}
public class Main { public static void main(String[] args) { Greet obj = new Greet(); obj.greet(); obj.displayName(); }}Output:
HELLO QUIPO HOUSEKey Points
- Methods enhance code reusability and maintainability.
- Static methods belong to the class and can be called without creating an object.
- Instance methods require an object to be called.
- Abstract methods provide a blueprint for subclasses, enforcing implementation.
Tips: Use methods to keep your code modular, readable, and easy to maintain. Choose the appropriate type of method based on your use case and design requirements.
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