Java Tutorial Blog

How to Call Method in Java

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In programming, the functions and methods serve as a prerequisite in implementing the required functionalities. These approaches are often used in programming by a noob programmer as well as a developer to create templates for the passed values. While defining these functionalities, it is also important to invoke/call these features to reflect the changes in the code.

How to Call Method in Java?

A method to be called in Java can be of various types, listed below:

  • Static Method.
  • Predefined Method.
  • User-defined Method.
  • Abstract Method

Note: A method can be overloaded and called which will be discussed later in the example.

Example 1: Calling a Static Method

This example calls a static method:

public class Methodcall {
public static void main(String args[]) {
  double x;
  x= Math.pow(2, 3);
  System.out.println("Value -> " + x);
}}

In this code, invoke a static method of the “Math” class to compute the power of 2 as 3 and return the outcome.

Output

Example 2: Calling a Predefined Method

This demonstration calls a predefined method of the “ArrayList” class:

import java.util.ArrayList;
public class Methodcall {
public static void main(String[] args) {
  ArrayList<Integer> items = new ArrayList<>();
  items.add(1);
  items.add(2);
  System.out.println("ArrayList Elements -> ");
  items.stream().forEach(System.out::println);
}}

In this code, call a predefined method “add()” of the ArrayList to insert the given integers into the created ArrayList and return the traversed array elements via the “for-Each” loop.

Output

Example 3: Calling a User-Defined Method

In this particular example, the user-defined “static” and “non-static” methods will be accessed:

public class Methodcall {
static void displayOut1() {
  System.out.println("This is a static user-defined function");
}
void displayOut2() {
  System.out.println("This is a non-static user-defined function");
}
public static void main(String[] args) {
  displayOut1();
  Methodcall x = new Methodcall();
  x.displayOut2();
}}

According to this snippet of code:

  • Define a user-defined static and non-static methods, respectively comprising the given messages.
  • In “main”, invoke the static method directly.
  • After that, create a class object to access the non-static method.

Output

Example 4: Calling an Abstract Method

This specific example calls an abstract method:

abstract class AbstractMethodExample{
abstract void display();
}
public class Methodcall extends AbstractMethodExample {
  void display() {
  System.out.println("Abstract Method Invoked!");
}
public static void main(String[] args){
  Methodcall x = new Methodcall();
  x.display();
}}

In this code:

  • Specify an abstract method in an abstract class.
  • Now, the public class extends this class and defines the specified abstract method with the given message statement.
  • In “main”, create an object of the main class and call the abstract method.

Output

Example 5: Overloading a Method

This code example overloads a method with the same name and then calls both the methods:

public class Methodcall {
static int add(int a, int b){
  return a + b;
}
static double add(double a, double b){
  return a + b;
}
public static void main(String[] args){
  System.out.println("Addition of Integers -> " +add(33, 45));
  System.out.println("Addition of Doubles -> " +add(2.32, 3.323));
}}

In the above code lines:

  • Define a method “add()” returning the addition of the passed integers.
  • Now, overload the defined method with the same name by returning the addition of the passed doubles instead.
  • In “main”, invoke both the functions with the passed integer and double values, respectively.

Output

Conclusion

A method in Java can be called directly, via an associated class etc. Calling a method depends on the type of method being invoked. This type can be static, predefined, user-defined, or abstract. Also, a method can be overloaded with the same name and invoked.