Methods and Arrays

Methods let you break code into reusable, named blocks. Arrays let you store multiple values of the same type in a single variable. Together they are foundational building blocks for every Java program.

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Defining Methods

A method has a return type, a name, and zero or more parameters:

public static int add(int a, int b) {
    return a + b;
}

Method Signature Breakdown

accessModifier  static  returnType  methodName(parameterList) {
    // body
}

Part	Example	Meaning
public	Access modifier	Visible everywhere
static	Belongs to class	Can be called without creating an object
int	Return type	The method returns an integer
add	Method name	How you call the method
(int a, int b)	Parameters	Input values

Calling a Method

int result = add(3, 7);  // result = 10

Void Methods

Methods that do not return a value use void:

public static void greet(String name) {
    System.out.println("Hello, " + name + "!");
}

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Method Overloading

You can define multiple methods with the same name but different parameter lists:

public static int add(int a, int b) {
    return a + b;
}

public static double add(double a, double b) {
    return a + b;
}

public static int add(int a, int b, int c) {
    return a + b + c;
}

The compiler selects the correct method based on the argument types.

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Varargs (Variable Arguments)

Use ... to accept a variable number of arguments:

public static int sum(int... numbers) {
    int total = 0;
    for (int n : numbers) {
        total += n;
    }
    return total;
}

// Usage:
sum(1, 2);           // 3
sum(1, 2, 3, 4, 5);  // 15

Tip: Varargs must be the last parameter in the method signature.

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Arrays

An array is a fixed-size, ordered collection of elements of the same type.

Declaring and Initialising

// Declare and allocate
int[] numbers = new int[5];      // 5 elements, all initialised to 0

// Declare and initialise with values
int[] scores = {90, 85, 78, 92, 88};

// Access elements (0-indexed)
int first = scores[0];   // 90
int last = scores[4];    // 88