Javase Programming Fundamentals 5

Javase Programming Fundamentals 5

Arrays and methods;

Syntax: Access modifier symbol return type method name () {

Method body;

}

Note: (1), method to be directly defined in class;

(2), the design method is designed to achieve the reuse of functions;

First, define the declaration method;

1 , write the method directly within class:

Cases:

 Public void checkIn () {System. out. println (" breaking Through the night sky, stepping into the dawn ");}

Type:

Void (no parameters, no return results), Int,string,float,double,boolean;

2 , at main entrance:

A variable defined by a class becomes an object;

Syntax: Class name variable (object) = new class name ();

New is to open up a new space;

Method invocation: Variable (object). Method name ();

3. naming rules for full names:

(1) , letters, underscores, numbers, $; cannot begin with numbers;

(2) , package name: must all be lowercase letters;

(3) , file name: initials and the first letter of the following English words should be capitalized;

(4) , variable and method name: first letter lowercase, the following English word capitalization;

4. call a method principle with parameters:

(1) , the number of parameters should be consistent;

(2) , type to be consistent;

(3) , the order should be consistent;

(4) , the parameter has the function of passing;

(5) and two parameters separated by commas (,);

(6) , passing the data given at the time of invocation to the running method;

Second, types of methods;

1. no parameters, no return results;

Example:1, no parameters, no return results;

Method is written to:

 Public void checkIn () {      System. out. println (" breaking Through the night sky, stepping into the dawn ");   }

To run the program's write:

     // New opens up a space;　　　New Person ();        Liming.checkin ();

2, there are parameters, no return results;

Example: There are parameters, no return results;

Write method within person;

 Public void checkwn (int  ID) {      if(id==1) {         System. out. println (" sign in ");      } Else {         System. out. println (" sign in ");      }   }

Write the running program in Exam_1;

// New opens up a space;  New person (); Liming.checkwn (N);

3. having parameters, having the result of returning;

Example: There are parameters, there are return results;

Write the method in public;

   Public int numberadd (int n1,int  n2) {      return n1*n2;   }

Write the running program in Exam_1;

int i = liming.numberadd (35); System. out. println (" the product of two numbers is:"+i);

4, texting example;

To write a method in person:

 Public void duanxin () {      new Scanner (System.  in);      System. out. println (" Please enter the contents of the text message:");       = Input.next ();      System. out. println (" input content is:"+Sun);   }

Write the running program in Exam_1;

　

　// New opens up a space; New person (); liming.duanxin;    

5, judge the user login example:

Write the method in person;

 Public boolean Yonghu (String username,string password) {      if(Username.equals ("Qizhi  ") && password.equals ("1763")         {return  true;      } Else {         returnfalse;      }}

Write the running program in Exam_1;

Scanner input =NewScanner (System.inch); String Username,password;boolean Flag; System. out. println ("Welcome to the Mini DVD system"); System. out. println ("Please enter user name:"); Username=Input.next (); System. out. println ("Please enter your password:"); Password=Input.next (); Flag=Liming.yonghu (Username,password); if(Flag = =true) {System. out. println ("User Login Successful"); }Else{System. out. println ("user logon Failed "); }   }

6, to find two numerical methods and examples;

To write a method in Calcalator:

 Public int calc (intint  b) {return a +b;}

Write the running program in Test_1:

Scanner input = new Scanner (system.in); int n1,n2,sum; System.out. Printin ("Please enter the first value:"); n1 = input.nextint (); System.out. println ("Please enter a second value:"); n2 = Input.nextint ();

To open up a new space;

Calc jsq = new Calc ();

Call method;

sum = Jsq.calc (N1,N2);

System.out.printl (String.Format ("%d+%d=%d", N1,n2,sum));

Javase Programming Fundamentals 5