Class 4 and objects

Class 4 and objects

2. The difference between a class and an object
   1. Classes are abstract and conceptual and represent a class of things, such as humans and animals...
   2. Objects are specific and actually exist, representing a specific food
   3. A class is an object template. An object is an instance of a class. Classes are used to instantiate an object. For example, a specific person who creates a wheat by a person.
4. How to defineClass?
6. How to createObject? -- Two methods
   1. First
      1. Object Declaration: Class Name Object Name
      2. Object creation: Object Name = New Class Name ()
   2. Second: One-step deployment
      1. Class Name object name = New Class Name ();
8. The first letter of the class name is capitalized;
9. Class member method (member function) Definition
   3. 
      Program As follows:

       
      1:/*
       

       
      2:* Member methods without return values by printing pyramid exercises
       

      3:*/
       

       
      4:Package lesson4;
       

       
      5:Public Class_ 3 printjinzita {
       

       
      6:/**
       

       
      7:* @ Param ARGs
       

       
      8:*/
       

       
      9:Public Static VoidMain (string [] ARGs ){
       

       
      10:// Todo auto-generated method stub
       

      11:Printjinzita myprintjinzita =NewPrintjinzita (9 );
       

       
      12:Myprintjinzita. printhalf ();
       

       
      13:Myprintjinzita. Print ();
       

       
      14:}
       

       
      15:}
       

       
      16:// Print the pyramid class
       

       
      17:ClassPrintjinzita {
       

       
      18:// Define the print Layers
       

       
      19:Private IntN = 0;
       

      20:PublicPrintjinzita (IntN ){
       

       
      21:This. N = N;
       

       
      22:}
       

       
      23:// Print the right half of the pyramid
       

       
      24:Public VoidPrinthalf (){
       

       
      25:For(IntI = 0; I <n; I ++ ){
       

       
      26:For(IntJ = 0; j <I + 1; j ++ ){
       

      27:System.Out. Print ("*");
       

       
      28:}
       

       
      29:System.Out. Println ();
       

       
      30:}
       

       
      31:}
       

       
      32:// Print the pyramid
       

       
      33:Public VoidPrint (){
       

       
      34:IntHalf_n = (This. N * 2-1)/2;
       

      35:For(IntI = 0; I <n; I ++ ){
       

       
      36:For(IntL = 0; L  
       
      37:System.Out. Print ("");
       
       
      38:}
       
       
      39:For(IntK = 0; k <I; k ++ ){
       
       
      40:System.Out. Print ("*");
       
       
      41:}
       
      42:For(IntJ = 0; j <I + 1; j ++ ){
       
       
      43:System.Out. Print ("*");
       
       
      44:}
       
       
      45:System.Out. Println ();
       
       
      46:}
       
       
      47:}
       
       
      48:}
       

1. 3.  
      1:The procedure is as follows:
       

       
      2:/*
       

       
      3:* Function: print the ninth multiplication table of mathematics and the member methods of the exercise class.
       

      4:*/
       

       
      5:Package lesson4;
       

       
      6:Public Class_ 4 chengfabiao {
       

       
      7:/**
       

       
      8:* @ Param ARGs
       

       
      9:*/
       

       
      10:Public Static VoidMain (string [] ARGs ){
       

       
      11:// Todo auto-generated method stub
       

      12:Chengfabiao =NewChengfabiao (9 );
       

       
      13:}
       

       
      14:}
       

       
      15:ClassChengfabiao {
       

       
      16:PublicChengfabiao (IntN ){
       

       
      17:For(IntI = 1; I <= N; I ++ ){
       

       
      18:For(IntJ = 1; j <= I; j ++ ){
       

      19:System.Out. Print (J +"*"+ I +"="+ I * j +"");
       

       
      20:If(I = 3 & J = 2) | (I = 4 & J = 2 )){
       

       
      21:System.Out. Print ("");
       

       
      22:}
       

       
      23:}
       

       
      24:System.Out. Println ();
       

       
      25:}
       

       
      26:}
       

      27:}
       

4. 1. Constructor is a special method with the following features.
      (1) The method name of the constructor must be the same as the class name.

      (2) The constructor does not return a type and cannot be defined as void. The method type is not declared before the method name.

      (3)The main function of constructor is to complete object initialization. It can pass the parameters when defining an object to the object's domain.

      (4) The constructor cannot call the constructor, but must call the constructor.

      (5) A class can define multiple constructor methods. If no constructor is defined when a class is defined, the compilation system automatically inserts a default constructor without parameters, this constructor does not execute anyCode.

      (6) The constructor can be overloaded and distinguished by the number, type, or order of parameters.

      I personally think that there is no returned rule, but it is actually an object of the class returned implicitly.

5. Case: Implement element transpose of a Matrix
   
   The procedure is as follows:

    
   1:/*
    

    
   2:* Function: transpose a three-dimensional matrix and associate the member methods of the class.
    

    
   3:*/
    

    
   4:Package lesson4;
    

   5:Public Class_ 5 shuzuzhuanzhi {
    

    
   6:/**
    

    
   7:* @ Param ARGs
    

    
   8:*/
    

    
   9:Public Static VoidMain (string [] ARGs ){
    

    
   10:// Todo auto-generated method stub
    

    
   11:Shuzuzhuanzhi =NewShuzuzhuanzhi ();
    

    
   12:}
    

   13:}
    

    
   14:ClassShuzuzhuanzhi {
    

    
   15:PublicShuzuzhuanzhi (){
    

    
   16:IntTemp = 0;
    

    
   17:Int[] [] Myarr = {1, 2, 3}, {4, 5, 6}, {7, 8, 9 }};
    

    
   18:For(IntI = 0; I <3; I ++ ){
    

    
   19:For(IntJ = I + 1; j <3; j ++ ){
    

    
   20:Temp = myarr [I] [J];
    

   21:Myarr [I] [J] = myarr [J] [I];
    

    
   22:Myarr [J] [I] = temp;
    

    
   23:}
    

    
   24:}
    

    
   25:For(IntI = 0; I <3; I ++ ){
    

    
   26:For(IntJ = 0; j <3; j ++ ){
    

    
   27:System.Out. Print (myarr [I] [J] +"");
    

    
   28:}
    

   29:System.Out. Println ();
    

    
   30:}
    

    
   31:}
    

    
   32:}