The difference between class and object in Scala

1. Class

Scala classes are a bit different from classes in C #, such as declaring a field that is not priavate decorated var age,scala compiler field helps us to produce a private field and 2 public method get and set, which is similar to C # 's simple properties; If you use the private adornment , its methods will also be private. This is the so-called unified access principle.

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2. Class is the public level by default
4. Class person{
6. var age= //field must be initialized ()
8. def age=age //This is the method, no parameters can be omitted ()
10. Def incremen () {this.age+=1}
12. }
18. Class student{
20. var age= ///The underlying compiler automatically adds a public method of get and set to the private age, which can be understood as pseudo type
22. private[this] var gender="male" //private[this] only this class can use the
24. Private var name="Clow" //declares private, the underlying compiler automatically adds the get and set proprietary methods for the private name
26. //But you can define your own property methods
28. def getname=THIS.name
30. def setName (value:string) {This.name=value}
32. }
36. Use of constructors
38. Class Teacher {
40. var Age:int = _
42. var name:string = _ //Can be reserved
46. //Overloaded constructors are similar to the public Teacher () {} inside C #
48. def this (Age:int, name:string) {
50. This () //must be called once for the main constructor
52. This.age=age
54. This.name=name
56. }
58. }

2, Scala does not have static modifiers, but the members under object are static, if there is a class with the same name, this is its associated class. In object, you can generally do some initialization for the associated class, such as the Val Array=array (PS: It uses the Apply method) that we often use

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1. Object dog{
2. private var age=0
3. def age={
4. age+=1
5. Age
6. }
7. }
9. Class dog{
10. var age1=dog.age //dog.age is a private field of object Dog. It reminds me of the friend class of C + + .
11. }

3, how to explain the use of apply? Let's see how we can use it to implement a singleton pattern.

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2. Class Applytest private{ //Add private hidden constructor
4. Def SayHello () {
6. println ("Hello Jop")
8. }
10. }
14. Object applytest{
16. var instant:applytest=Null
18. def apply () ={
20. if (instant==null) instant=new applytest
22. Instant
26. }
28. }
32. Object Applydemo {
34. def main (args:array[string]) {
36. Val T=applytest ()
38. T.sayhello ()
40. }
42. }

The difference between class and object in Scala