Scala Learning (vi) practice

Objects & Exercises in Scala

1. Write a Conversions object and add the Inchestocentimeters,gallonstoliters and Milestokilometers methods

Program code:

2. Object Conversions {
4. Private Val i2c=30.48
6. Private Val g2l=3.785411784
8. Private Val m2k=1.609344
10. def inchestocentimeters (inch:double):D ouble={
12. Inch*i2c
14. }
16. def gallonstoliters (gallon:double):D ouble={
18. gallon*g2l
20. }
22. def milestokilometers (mile:double):D ouble={
24. mile*m2k
26. }
28. def main (args:array[string]): Unit = {
30. Val inch=15
32. Val gallon=15
34. Val mile=15
36. println (inch+ " ft = " +inchestocentimeters (inch))
38. println (gallon+ " gal = " +gallonstoliters (gallon))
40. println (mile+ " km = " +milestokilometers (mile))
42. }
44. }

Operation Result:

the feet = 457.2

the gallons = 56.78117676

the km = 24.14016

2. The previous exercise was not very object-oriented. Provides a generic superclass unitconversion and defines the inchestocentimeters,gallonstoliters and Milestokilometers objects that extend the superclass

Program code:

2. Abstract class unitconversion {
4. def Converse (from:double):D ouble
6. }
8. Object inchestocentimeters extends unitconversion{
10. Private Val i2c=30.48
12. Override Def Converse (inche:double):D ouble={
14. Inche*i2c
16. }
18. }
20. Object gallonstoliters extends unitconversion{
22. Private Val g2l=3.785311784
24. Override Def Converse (gallon:double):D ouble={
26. G2l*gallon
28. }
30. }
32. Object milestokilometers extends unitconversion{
34. Private Val m2k=1.609344
36. Override Def Converse (mile:double):D ouble={
38. M2k*mile
40. }
42. }
44. Object test{
46. def main (args:array[string]): Unit = {
48. Val inche=10; Val gallon=10; Val mile=10
50. println (inche+ " ft = " +inchestocentimeters.converse (inche) + " cm ")
52. println (gallon+ " gal = " +gallonstoliters.converse (gallon) + " liter ")
54. println (mile+ " km = " +milestokilometers.converse (mile) + " km ")
56. }
58. }

Operation Result:

Ten feet = 304.8 centimeters

Ten gallons = 37.85311784 liters

Ten km = 16.09344 km

3. Define an Origin object that extends from Java.awt.Point. Why this is actually not a good idea (look at the method of the point class carefully)

Description: The GetLocation method in point returns a Point object and requires the Origin class to return to the Origin object. Point has a Move method, SetLocation method. These are not very suitable as Origin (origin).

Program code:

Import Java.awt.Point

Object Origin extends point with app{

Override Def getlocation:point=super.getlocation ()

Origin.move (2, 3)

println (origin.tostring ())

}

4. Define a point class and a companion object so that we can construct a point instance directly with point (3,4) without new

Description: The Apply method uses

Program code:

Class Point (X:int,y:int) {

Override Def toString (): string= "x=" +x+ "y=" +y

}

Object Point extends app{

def apply (X:int,y:int) ={

New Point (x, y)

}

Val p=new Point (3,4)

println (P)

}

Operation Result:

x= 3 y= 4

5. Write a Scala app that uses app traits to print command line arguments in reverse order, separated by spaces. For example, Scala Reverse Hello world should print world Hello

Program code:

Object Reverse extends app{

for (str <-args.reverse)

println (str+ "")

}

Operation Result:

6. Write a poker 4-suit enumeration, and let its ToString method return ♣,♦,♥,♠

Description: The symbols of these four suits win the special symbol soft keyboard selected by the input method. You can use Vim under Lin. Enter :d IG in vim to find the respective cs,ch,cd,cc. Enter vim insert mode by <CTRL-K>, then enter it separately

Program code:

Object PokerFace extends Enumeration {

Type Pokerface=value

Val Spades=value ("♠")

Val Hearts=value ("♥")

Val diamonds=value ("? ")

Val clubs=value ("? ")

def main (args:array[string]): Unit = {

for (poker <-pokerface.values)

println (poker)

}

}

Operation Result:

♠

♥

?

?

7. Implement a function to check if the color of a card is red

Program code:

2. Object Card extends enumeration with app{
4. Val spades=value ("?")
6. Val hearts=value ("?")
8. Val diamonds=value ("?")
10. Val clubs=value ("?")
12. Type Card=value
14. def color (c:card) ={
16. if (c==card.hearts| | C==card.diamonds)
18. println ("Red")
20. Else
22. println ("Black")
24. }
26. Color (Spades)
28. Color (DIAMONDS)
30. }

Operation Result:

Black

Red

8. Write an enumeration that describes the 8 corners of an RGB cube. ID uses color values (for example: Red is 0xff0000)

Description: RGB If the 8-bit representation, red is 0xff0000, Green is 0x00ff00, Blue is 0x0000ff. And so on, 8 vertices were (0,0,0) (0,0,1) (0,1,0) (0,1,1) (1,0,0) (1,0,1) (1,1,0) (1,1,1)

Program code:

Object rgb extends enumeration with app {  

val red = value (0xff0000, "RED")   

val black  = value (0x000000, "Black")   

val green =  Value (0x00ff00, "Green")   

val cyan = value (0X00FFFF, "Cyan")   

val yellow = value (0xffff00, "YELLOW")   

val white = value (0xFFFFFF, "white")   

val blue = value (0X0000FF, "BLUE")   

val magenta = value (0xff00ff, "MAGENTA")   

}  

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Scala Learning (vi) practice