Java object-oriented-method definition and simple use

The Java object-oriented approach

Methods are part of an object, also known as behavior;

Let's start with a simple example:

1  Packagecom.java1234.chap03.sec03;2  3  Public classPerson {4  5     voidspeak () {6System.out.println ("I am Zhang San");7     }8      9      Public Static voidMain (string[] args) {TenPerson person=NewPerson (); One person.speak (); A     } -}

The above is a non-parametric method, we changed, changed to a parameter, the name we call the method when determined. Add a name parameter;

On the code:

1  Packagecom.java1234.chap03.sec03;2  3  Public classPerson {4  5     voidspeak (String name) {6 System.out.println (name);7     }8      9      Public Static voidMain (string[] args) {TenPerson person=NewPerson (); OnePerson.speak ("Zhang San"); A     } -}

method, we can also have multiple parameters, separated by commas , we add an age parameter:

On the code:

1  Packagecom.java1234.chap03.sec03;2  3  Public classPerson {4  5     voidSpeak (String name,intAge ) {6System.out.println ("My name is +name+", I'm "+age+" this year.);7     }8      9      Public Static voidMain (string[] args) {TenPerson person=NewPerson (); OnePerson.speak ("Zhang San", 23); A     } -}

And if we want to add hobbies, the number of hobbies is not fixed, this time we can use the non-fixed parameters

On the code:

1  Packagecom.java1234.chap03.sec03;2  3  Public classPerson {4  5     voidSpeak (String name,intAge ,String ... hobbies) {6System.out.println ("My name is +name+", I'm "+age+" this year.);7          for (String hobby:hobbies){8System.out.println (hobby+ "");9         }Ten     } One       A      Public Static voidMain (string[] args) { -Person person=NewPerson (); -Person.speak ("Zhang San", 23, "swimming", "singing"); the     } -}

Return value of the method: Returns the number of hobbies

On the code:

1  Packagecom.java1234.chap03.sec03;2  3  Public classPerson {4  5     intSpeak (String name,intAge ,String ... hobbies) {6System.out.println ("My name is +name+", I'm "+age+" this year.);7          for(String hobby:hobbies) {8System.out.println (hobby+ "");9         }Ten         //get the length of your hobby One         inttotalhobbies= hobbies.length; A         returntotalhobbies; -     } -       the      Public Static voidMain (string[] args) { -Person person=NewPerson (); -         intN=person.speak ("Zhang San", 23, "swimming", "singing"); -System.out.println ("Have" +n+ "a hobby"); +     } -}

Of course, the return type is either int or string, float, etc. include object

Java object-oriented-method definition and simple use