METHODS IN JAVA

• Methods


  collection of statements that are grouped together to perform an operation. Also known as functions.
• Types of Java Methods:

  • Standard Library Methods
  • User-defined methods
• All methods — including the main method — must begin with a method declaration. Here’s the basic form of a method declaration:

  visibility [static] return-type method-name (parameter-list)

  {

  statements…

  }
• Method declaration: visibility


  determines whether the method is available to other classes.
• Method declaration: public


  Allows any other class to access the method
• Method declaration: private


  Hides the method from other classes
• Method declaration: protected


  Lets subclasses use the method but hides the method from other classes
• Method declaration: static


  This optional keyword declares that the method is static, meaning you can call it without first creating an instance of the class in which it’s defined. The main method must always be static, and any other methods in the class containing the main method should also be static.
• Method declaration: return-type


  indicates whether the method returns a value when it is called — and if so, what type the value is. If the method doesn’t return a value, specify void.
• Method declaration: method-name


  The rules for making up method names are the same as the rules for creating other identifiers: Use any combination of letters and numbers, but start with a letter.
• Method declaration: parameter list


  You can pass one or more values to a method by listing the values in parentheses following the method name. The parameter list in the method declaration lets Java know what types of parameters a method should expect to receive and provides names so that the statements in the method’s body can access the parameters as local variables.
• Method declaration: statements


  One or more Java statements that comprise the method body, enclosed in a set of braces. Unlike Java statements such as if, while, and for, the method body requires you to use the braces even if the body consists of only one statement.
• How to create a user-defined method:

  You can see three keywords public, static and void before the function name.

  • The public keyword makes myMethod() method public. Public members can be accessed from outside of the class.
  • The static keyword denotes that the method can be accessed without creating the object of the class.
  • The void keyword signifies that the method doesn’t return any value.

  
• Public keyword


  Public members can be accessed from outside of the class.
• Static keyword


  denotes that the method can be accessed without creating the object of the class.
• Void keyword


  signifies that the method doesn’t return any value
• How to call a Java method:

  Before you can use (call a method), you need to define it.

  
• Example. Method (return no value and no parameter)

  // Welcome to display information method

  
• Example. Method (return no value and no parameter)

  //

  display 1

  display 2

  
• Example. Method (return no value and have parameter)

  // 300

  
• Example. Method with Arguments and Return Value

  // 100

  
• Example. Method with Arguments and Return Value

  // Rommel 80