class

Why am I getting the error implicitly converting type double to an int?

由 老子叫甜甜 提交于 2020-04-17 22:17:11
问题 How do I fix the error "Cannot implicitly convert type 'double' to 'int'. An explicit conversion exists (are you missing a cast?). I don't see where I am changing an int to a double. Here's the following code I am working with: namespace Chapter_9 { class Program { static void Main(string[] args) { Circle create = new Circle(); create.SetRadius(2); WriteLine("Radius = {0}", create.GetRadius()); WriteLine("Diameter = {0}", create.GetDiameter()); WriteLine("Area = {0}", create.GetArea()); } }

Updating multiple items in a class, not just one

由 拥有回忆 提交于 2020-04-16 08:34:43
问题 In the update section of this code, only the first bat that gets made is affected by update() in class Bat()... Outside of main loop: START_BAT_COUNT = 30 BAT_IMAGE_PATH = os.path.join( 'Sprites', 'Bat_enemy', 'Bat-1.png' ) bat_image = pygame.image.load(BAT_IMAGE_PATH).convert_alpha() bat_image = pygame.transform.scale(bat_image, (80, 70)) class Bat(pygame.sprite.Sprite): def __init__(self, bat_x, bat_y, bat_image, bat_health): pygame.sprite.Sprite.__init__(self) self.bat_health = bat_health

Updating multiple items in a class, not just one

由 北城余情 提交于 2020-04-16 08:34:09
问题 In the update section of this code, only the first bat that gets made is affected by update() in class Bat()... Outside of main loop: START_BAT_COUNT = 30 BAT_IMAGE_PATH = os.path.join( 'Sprites', 'Bat_enemy', 'Bat-1.png' ) bat_image = pygame.image.load(BAT_IMAGE_PATH).convert_alpha() bat_image = pygame.transform.scale(bat_image, (80, 70)) class Bat(pygame.sprite.Sprite): def __init__(self, bat_x, bat_y, bat_image, bat_health): pygame.sprite.Sprite.__init__(self) self.bat_health = bat_health

Can one declare a static method within an abstract class, in Dart?

由 安稳与你 提交于 2020-04-12 20:59:07
问题 In an abstract class , I wish to define static methods, but I'm having problems. In this simple example abstract class Main { static String get name; bool use( Element el ); } class Sub extends Main { static String get name => 'testme'; bool use( Element el ) => (el is Element); } I receive the error: function body expected for method 'get:name' static String get name; Is there a typo in the declaration, or are static methods incompatible with abstract classes? 回答1: Dart doesn't inherit

Can one declare a static method within an abstract class, in Dart?

由 故事扮演 提交于 2020-04-12 20:52:25
问题 In an abstract class , I wish to define static methods, but I'm having problems. In this simple example abstract class Main { static String get name; bool use( Element el ); } class Sub extends Main { static String get name => 'testme'; bool use( Element el ) => (el is Element); } I receive the error: function body expected for method 'get:name' static String get name; Is there a typo in the declaration, or are static methods incompatible with abstract classes? 回答1: Dart doesn't inherit

Can one declare a static method within an abstract class, in Dart?

由 允我心安 提交于 2020-04-12 20:51:09
问题 In an abstract class , I wish to define static methods, but I'm having problems. In this simple example abstract class Main { static String get name; bool use( Element el ); } class Sub extends Main { static String get name => 'testme'; bool use( Element el ) => (el is Element); } I receive the error: function body expected for method 'get:name' static String get name; Is there a typo in the declaration, or are static methods incompatible with abstract classes? 回答1: Dart doesn't inherit

Sealed classes inside another class in Kotlin can't be compiled: cannot access '<init>' it is private

由 ＊爱你＆永不变心＊ 提交于 2020-04-12 08:14:12
问题 If I used the example from the docs, class SomeActivity : AppCompatActivity() { sealed class Expr data class Const(val number: Double) : Expr() data class Sum(val e1: Expr, val e2: Expr) : Expr() object NotANumber : Expr() } it does not compile, with the error: Cannot access '<init>', it is private in 'Expr'. However, moving it outside the enclosing class makes it compile: sealed class Expr data class Const(val number: Double) : Expr() data class Sum(val e1: Expr, val e2: Expr) : Expr()

Python: defining a function with variable number of arguments

由 纵饮孤独 提交于 2020-04-11 11:44:06
问题 I am not sure if this thing has a name, so I couldn't find any information online so far, although surely there is! Imagine my MWE: def PlotElementsDict(dictionary1, dictionary2, itemToPlot, title): # dictionary 1 and dictionary 2 are collections.OrderedDict with 'key':[1,2,3] # i.e. there values of the keys are lists of numbers list1 = [dictionary1[key][itemToPlot] for key in dictionary1.keys()] list2 = [dictoinary2[key][itemToPlot] for key in dictionary2.keys()] plt.plot(list1, label='l1, {

Use 'navigation' and 'route' inside header present in class - React-navigation v5

由 你。 提交于 2020-04-10 05:31:43
问题 I'm stuck as I want to switch to the V5 version of react-navigation. With v4, I used to pass my params and use them with : Set : this.props.navigation.navigate('MyDestination', {myParam: 'value'}) Get : this.props.navigation.getParam('myParam') With v5, some things changed and I now can't use the this.props.navigation since it's not seemed to be known by the app. My code is splitted so I have my App.js that only refer to the Navigation class : import React from 'react'; import { StyleSheet,

Java 反射

由 送分小仙女□ 提交于 2020-04-08 11:47:31
反射 （Reflection） : 在多个类没有公共特性时， 可以在一个基类方法中， 通过反射， 实现对这些没有公共特性的类的普遍性调用。 一：class.getMethod() 　　①//getMethod(String name, Class<?>... parameterTypes) 　　 Method method = class.getMethod("要调用的方法名称","要调用的方法的形参的类型的class"); ②//invoke(Object obj, Object... args) 　　 method.invoke("对象实例","要调用的方法的形参"); 1 public class ReflectiveTest { 2 3 public static void reflectiveMethod(Object object) { 4 5 System.out.println("-------------反射使用方法--------------"); 6 7 Class<?> clazz = object.getClass(); 8 try { 9 10 //getMethod():第一个参数方法名称；第二个参数：方法的形参的class 11 Method sitMethod = clazz.getMethod("sit",null); 12 sitMethod
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