Methods

Methods are blocks of code that perform specific tasks. They help organize code, enable reuse, and provide abstraction.

Method Declaration

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

A method declaration includes:

• Access modifier (public)
• Return type (int)
• Method name (calculateSum)
• Parameters (int a, int b)
• Method body (code between curly braces)

Method Invocation

int result = calculateSum(5, 3); // result = 8

Static vs. Instance Methods

Static Methods

• Belong to the class rather than objects
• Called using the class name
• Cannot access instance variables directly

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

// Calling a static method
int sum = MathHelper.add(5, 3);

Instance Methods

• Belong to objects of the class
• Require an instance to be called
• Can access instance variables

public class Calculator {
  private int memory;

  public void store(int value) {
    memory = value;
  }

  public int recall() {
    return memory;
  }
}

// Using instance methods
Calculator calc = new Calculator();
calc.store(10);
int value = calc.recall(); // value = 10

Method Parameters

Parameter Passing

• Primitive types are passed by value (a copy is passed)
• Objects are passed by reference value (a copy of the reference is passed)

public void modifyValues(int number, StringBuilder text) {
  number = 100; // Only modifies the local copy
  text.append(" World"); // Modifies the actual object
}

int n = 5;
StringBuilder sb = new StringBuilder("Hello");
modifyValues(n, sb);

System.out.println(n); // Still 5
System.out.println(sb); // "Hello World"

Method Recursion

A method that calls itself:

public int factorial(int n) {
  if (n <= 1) {
    return 1; // Base case
  }
  return n * factorial(n - 1); // Recursive case
}

Best Practices

1. Single Responsibility: A method should do one thing well
2. Descriptive Names: Method names should clearly describe what they do