Subash

Posted on Nov 3 Edited on Nov 3

Methods in Java

#methodinjava #java #ai #method

What is a Method?

A method is a block of code that performs a specific task. We can create a method once and call it whenever required.

Methods help us to reuse code and avoid repetition.

How to Create a Method?

Syntax:

accessModifier returnType methodName(parameters) {
    // Method body
}

Example:

public class Main {

    static void greet() {
        System.out.println("Hello World");
    }

    public static void main(String[] args) {
        greet();
    }
}

Types of Methods

1) Predefined Methods

Methods that are already available in Java libraries.

String name = "java";

System.out.println(name.toUpperCase());
System.out.println(name.length());

2) User-Defined Methods

Methods created by programmers to perform specific tasks.

static void display() {
    System.out.println("Learning Java");
}

Parameters and Arguments

Parameters: Variables declared in the method definition.
Arguments: Actual values passed when calling the method.

static void add(int a, int b) {
    System.out.println(a + b);
}

add(10, 20);

Here, a and b are parameters, whereas 10 and 20 are arguments.

Return Type

A return type specifies the type of value a method returns.

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

Here, int is the return type, and the return keyword sends the result back to the calling method.

Void Method

When a method doesn't return any value, we use the void keyword.

static void display() {
    System.out.println("Hello Java");
}

Static and Instance Methods

1) Static Method

A static method belongs to the class. We can call it without creating an object.

static void display() {
    System.out.println("Static Method");
}

Main.display();

2) Instance Method

An instance method belongs to an object. We need to create an object to call it.

void display() {
    System.out.println("Instance Method");
}

Main obj = new Main();
obj.display();

Method Overloading

Method overloading means creating multiple methods with the same name but different parameters.

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

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

We can overload methods by changing the number, type or order of parameters.

Note: Changing only the return type is not method overloading.

Method Signature

A method signature consists of the method name and parameter types.

Example:

static int add(int a, int b)

Method signature: add(int, int)

Varargs

Varargs (Variable Arguments) allows a method to accept multiple arguments.

We use three dots (...) to declare it.

static void display(int... numbers) {

    for (int n : numbers) {
        System.out.println(n);
    }
}

Recursion

Recursion is a process in which a method calls itself.

static int factorial(int n) {

    if (n == 1)
        return 1;

    return n * factorial(n - 1);
}

Here, the method calls itself until the base condition is reached.

Pass by Value

Java always follows pass by value. It means a method receives a copy of the value passed to it.

static void change(int number) {
    number = 100;
}

public static void main(String[] args) {

    int value = 50;

    change(value);

    System.out.println(value);
}

Output:

Changing the copied value inside the method doesn't change the original variable.

Important Points

Methods help us reuse code.
void methods don't return values.
Static methods belong to classes.
Instance methods belong to objects.
Method overloading allows the same method name with different parameters.
Java always follows pass by value.
Recursion means a method calling itself.

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