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Questions & Solutions 💡

Method 👩‍💻

Java methods

A method is a block of code which only runs when it is called. You can pass data, known as parameters, into a method.

Methods are used to perform certain actions, and they are also known as functions.

Why use methods? To reuse code: define the code once, and use it many times.

Create a Method

A method must be declared within a class. It is defined with the name of the method, followed by parentheses (). Java provides some pre-defined methods, such as System.out.println(), but you can also create your own methods to perform certain actions:

Syntax👇

public class Main {
  static void myMethod() {
    // code to be executed
  }
}

Example Explained

  • myMethod() is the name of the method
  • static means that the method belongs to the Main class and not an object of the Main class
  • void means that this method does not have a return value

Call a Method

To call a method in Java, write the method's name followed by two parentheses () and a semicolon;

Example

Inside main, call the greeting method:

public class Main {
  static void greeting() {
    System.out.println("Hi Mom!");
  }

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

// Output: "Hi Mom!"

A method also can be called mutltiple times:

public class Main {
  static void greeting() {
    System.out.println("Hi Mom!");
  }

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

// Output: "Hi Mom!"
// Output: "Hi Mom!"
// Output: "Hi Mom!"

Java Methods Parameters

Information can be passed to methods as parameter. Parameters act as variables inside the method.

Parameters are specified after the method name, inside the parentheses. You can add as many parameters as you want, just separate them with a comma.

The following example has a method that takes a String called name as parameter:

public class Main {
  static void myMethod(String name, int age) {
    System.out.println("My name is " + name);
    System.out.println("I am " + age + " years old");
  }

  public static void main(String[] args) {
    myMethod("Ahmad", 21);
  }
}

// Output: My name is Ahmad
// Output: I am 21 years old

Return Values

The void keyword, used in the examples above, indicates that the method should not return a value. If you want the method to return a value, you can use a primitive data type (such as int, char, etc.) instead of void, and use the return keyword inside the method:

public class Main {
  static int addTwoNum(int x, int y) {
    return x + y;
  }

  public static void main(String[] args) {
    int num = addTwoNum(2, 3);
    System.out.println(num);
  }
}
// Outputs 5