Parameters,Arguments,Return Type

Parameters

• Parameters are the variables declared in the method definition that receives the values.
• Information passed to method as parameter.
• Parameter are specified after the method name,inside the parentheses.

Example

public class Main {
  static void myMethod(String fname) {
    System.out.println(fname + " Refsnes");
  }

  public static void main(String[] args) {
    myMethod("Liam");
    myMethod("Jenny");
    myMethod("Anja");
  }
}
// Liam Refsnes
// Jenny Refsnes
// Anja Refsnes

Method Parameters
Add as many parameters,and separate them with a commas.

public class Example {
    static void add(int a, int b) {   // a and b are parameters
        System.out.println(a + b);
    }

    public static void main(String[] args) {
        add(10, 20);
    }
}

Explanation
int a ,int b => are parameters

Arguments
Arguments are the actual values passed to the method when calling it.

Example

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

    public static void main(String[] args) {
        add(10, 20);   // 10 and 20 are arguments
    }
}

Explanation
10 and 20 are arguments

Return Type
• Return type defines what value a method returns
• void → no return value
• Other types (int, String, double, boolean) must use return statement
• Returned value goes back to the calling method
• Execution always starts from main()
• Without return type you cannot send data back

• A return type in Java is the data type of the value that a method sends back to the calling method after execution.
• When a method finishes its work, it can return a value using the return keyword.

Syntax

returnType methodName(parameters) {
    // code
    return value;
}

Explanation

returnType → int, double, String, boolean, etc.
methodName() → name of the method
parameters → input values
return value; → sends the result back to the caller

Flow of Execution
Example:

class Demo {

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

    public static void main(String[] args) {

        Demo obj = new Demo();

        int result = obj.add(5, 3);

        System.out.println(result);
    }
}

Step-by-Step Execution
Program starts from main()
Object is created
Demo obj = new Demo();
Method call happens
obj.add(5, 3)
Control goes to add() method
Calculation happens
5 + 3 = 8
return 8 sends value back
Value stored in result
Printed on screen

Output
8

Why Return Type is Used ?
- To Send Result Back

class Demo {

    static int add() {
        return 5 + 3;
    }

    public static void main(String args[]) {

        int result = add();

        System.out.println(result);
    }
}

Output

8

Here:

add() returns 8
main() receives it
Result is printed

1.Int Return Type
Returns an integer value.

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

    public static void main(String[] args) {
        System.out.println(add(5, 3));
    }
}

Output
8

2.Double Return Type
Returns a decimal number(Double Precision)

Example

public class Demo {
    static double divide(double a, double b) {
        return a / b;
    }

    public static void main(String[] args) {
        System.out.println(divide(10.5, 2.0));
    }
}

Output
5.25

3.Float Return Type
Returns a floating point number

Example

public class Demo {
    static float multiply(float a, float b) {
        return a * b;
    }

    public static void main(String[] args) {
        System.out.println(multiply(2.5f, 3.0f));
    }
}

Output
7.5

4.Char Return Type
Returns a single character

Example

public class Demo {
    static char getLetter() {
        return 'A';
    }

    public static void main(String[] args) {
        System.out.println(getLetter());
    }
}

Output
A

5.Boolean Return Type
Returns true or false

Example

public class Demo {
    static boolean isEven(int n) {
        return n % 2 == 0;
    }

    public static void main(String[] args) {
        System.out.println(isEven(6));
    }
}

Output
true

6.String Return Type
Returns a string(text)

Example

public class Demo {
    static String greet() {
        return "Hello Priya";
    }

    public static void main(String[] args) {
        System.out.println(greet());
    }
}

Output
Hello Priya

7.Void Return Type(No return type)
Method does not return any value

Example

public class Demo {
    static void message() {
        System.out.println("Welcome to Java");
    }

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

Example
Welcome to Java

Types Of Methods

1. Method with No Parameter and No Return Value
No input,does not return anything

class Demo {
    void greet() {
        System.out.println("Hello Priya");
    }

    public static void main(String[] args) {
        Demo d = new Demo();
        d.greet();
    }
}

Output
Hello Priya

Explanation
No Parameter inside ()
No Return Statement
Uses Void

2.Method with Parameter and No Return Value
takes input,does not return anything

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

    public static void main(String[] args) {
        Demo d = new Demo();
        d.add(5, 3);
    }
}

Output
8

Explanation
Takes parameter a and b
Prints result directly
Uses Void

3.Method with Parameter and Return Value
Takes input and return a value

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

    public static void main(String[] args) {
        Demo d = new Demo();
        int result = d.add(5, 3);
        System.out.println(result);
    }
}

Output
8

Explanation
Takes parameter
Returns result using return

4.Method with No Parameter but Return Value
Takes no input , return value

class Demo {
    int number() {
        return 10;
    }

    public static void main(String[] args) {
        Demo d = new Demo();
        int value = d.number();
        System.out.println(value);
    }
}

Output
10