Java Method Parameters
Passing data to methods
📥 What are Method Parameters?
Method parameters allow you to pass data into methods, making them flexible and reusable. Parameters act as variables that receive values when the method is called.
// Method with parameter
public static void greetPerson(String name) {
System.out.println("Hello, " + name + "!");
}
Output (when called with "Alice"):
Hello, Alice!
Key Parameter Concepts
Declaration
Define parameter type and name
void method(int number) {}Arguments
Values passed when calling method
method(42);Multiple
Methods can have multiple parameters
void method(int a, String b) {}Types
Parameters must have specific types
void method(double price) {}🔹 Single Parameter Example
Methods with one parameter:
public class ParameterExample {
// Method with String parameter
public static void sayHello(String name) {
System.out.println("Hello, " + name + "!");
}
// Method with int parameter
public static void printNumber(int num) {
System.out.println("The number is: " + num);
}
public static void main(String[] args) {
sayHello("John");
sayHello("Sarah");
printNumber(25);
printNumber(100);
}
}Output:
Hello, John!
Hello, Sarah!
The number is: 25
The number is: 100
🔹 Multiple Parameters
Methods can accept multiple parameters:
public class MultipleParameters {
// Method with two parameters
public static void introduce(String name, int age) {
System.out.println("Hi, I'm " + name + " and I'm " + age + " years old.");
}
// Method with three parameters
public static void calculateArea(int length, int width, String unit) {
int area = length * width;
System.out.println("Area: " + area + " " + unit);
}
public static void main(String[] args) {
introduce("Alice", 25);
introduce("Bob", 30);
calculateArea(5, 3, "square meters");
}
}Output:
Hi, I'm Alice and I'm 25 years old.
Hi, I'm Bob and I'm 30 years old.
Area: 15 square meters
🔹 Different Parameter Types
Parameters can be of different data types:
public class ParameterTypes {
// String parameter
public static void printMessage(String message) {
System.out.println("Message: " + message);
}
// Integer parameter
public static void printAge(int age) {
System.out.println("Age: " + age);
}
// Double parameter
public static void printPrice(double price) {
System.out.println("Price: $" + price);
}
// Boolean parameter
public static void printStatus(boolean isActive) {
System.out.println("Active: " + isActive);
}
public static void main(String[] args) {
printMessage("Welcome to Java!");
printAge(22);
printPrice(19.99);
printStatus(true);
}
}Output:
Message: Welcome to Java!
Age: 22
Price: $19.99
Active: true