What is a method?

A method is a block/group of code can be used to perform and accomplish a specific task. Methods allow us to write code more efficiently with less complexity. We have already used many methods in previous examples like – System.out.println(). The println() method is the predefined java method used to print a message on the console. Similarly, we can also create and use our own methods in the program.

What we can achieve with methods?

  1. We can avoid duplication.
  2. Allows reusability of code.
  3. Reduces the complexity of the program.
  4. Allows us to write code in a modular fashion.

How to create a method

A method is consists of 6 components – 

  1. Modifier – The modifier defines the access type of the method.
  2. Return type – The data type of the value if the method is returning any value otherwise void type.
  3. Method name – A valid method name.
  4. Parameter list – Comma separated multiple parameters or empty parentheses () for no parameter.
  5. Exception list – An optional exception list a method can throw.
  6. Method body – Body of the method, inside the method body we write our logic and codes.

Syntax

Following is the syntax for a java method –

<modifier> <return-type> <method-name> (<parameter list>) <exception list> {
    // method body
}

Example

Following is an example method returning a sum of two numbers-

public int sum(int a, int b) {

    int c = a + b;
    
    // Return sum of a and b
    return c;
}

To use the above method we need to call and pass two integer numbers in it, see the following example to better understand – 

// Get the sum of 10 and 20
int resultA = sum(10, 20);

// Get the sum of 10000 and 12345
int resultB = sum(10000, 12345);

We can call the method sum() multiple time as per our requirements.

Different examples

Following are the examples of methods try to run and modify the examples to better understand-

Void type method

A method not returning any value is considered as void type method. To create a void type method we use keyword ‘void’ in place of the return type.

MethodExample1.javaCopy
public class MethodExample1 {

    // A void type method
    public void sayHello(String name) {
        System.out.println("Hello, " + name);
    }

    public static void main(String[] args) {

        // Create object of class Main
        MethodExample1 obj = new MethodExample1();

        // Call the method
        obj.sayHello("John");

        // Call the method again
        obj.sayHello("Rock");

    }
}
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Return type method

A method can return any type of value at any point from inside the method body, but remember that method can return only once in its life cycle.

MethodExample2.javaCopy
public class MethodExample2{

    // A method to add two numbers
    public int add(int a, int b) {
        return a + b;
    }

    // A method to subtract number b from a
    public int subtract(int a, int b) {
        return a - b;
    }

    // A method to multiply number a with b
    public int multiply(int a, int b) {
        return a * b;
    }

    public static void main(String[] args) {

        // Create object of class Main
        MethodExample2 obj = new MethodExample2();

        int num1 = 10;
        int num2 = 5;

        // Calling method add(int, int)
        int add = obj.add(num1, num2);
        System.out.println("Addition: " + add);

        // Calling method subtract(int, int)
        int sub = obj.subtract(num1, num2);
        System.out.println("Subtraction: " + sub);

        // Calling method multiply(int, int)
        int mul = obj.multiply(num1, num2);
        System.out.println("Multiplication: " + mul);
    }
}
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No parameter method

Sometimes we need to create a method without the need for any parameters, this type of methods are considered as no parameter method.

MethodExample3.javaCopy
public class MethodExample3 {

    // Method without any parameters
    public void runLoop() {

        System.out.println("All items:");

        for(int i = 1; i <= 10; i++) {
            System.out.println("Item " + i);
        }
    }

    public static void main(String[] args) {

        // Create object of class Main
        MethodExample3 obj = new MethodExample3();

        // Call the method
        obj.runLoop();
    }
}
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Static method

Static methods are generally used as utility methods in program, a static method can only use static fields and can only invoke other static methods. The Java main() method is a good example of a static method.

To call a static method we don’t need to declare and initialize objects, we can directly invoke it by its class name.

MethodExample4.javaCopy
public class MethodExample4 {

    // A static method
    public static void runLoop() {

        System.out.println("All items:");

        for(int i = 1; i <= 10; i++) {
            System.out.println("Item " + i);
        }
    }

    public static void main(String[] args) {

        // Call the static method
        MethodExample4.runLoop();
    }
}
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