static

How do I call a non static method from a main method? [duplicate]

由 蓝咒 提交于 2020-05-08 08:02:49
问题 This question already has answers here : Java: how to call non static method from main method? (9 answers) Closed 4 years ago . For example, I am trying to do something like this public class Test { public static void main(String args[]) { int[] arr = new int[5]; arrPrint(arr); } public void arrPrint(int[] arr) { for (int i = 0; i < arr.length; i++) System.out.println(arr[i]); } } I get an error telling me that I can't reference non-static variables from static enviorments. So if that is true

How do I call a non static method from a main method? [duplicate]

由 半城伤御伤魂 提交于 2020-05-08 07:58:50
问题 This question already has answers here : Java: how to call non static method from main method? (9 answers) Closed 4 years ago . For example, I am trying to do something like this public class Test { public static void main(String args[]) { int[] arr = new int[5]; arrPrint(arr); } public void arrPrint(int[] arr) { for (int i = 0; i < arr.length; i++) System.out.println(arr[i]); } } I get an error telling me that I can't reference non-static variables from static enviorments. So if that is true

Refering to static methods from static variables

由 牧云@^-^@ 提交于 2020-04-17 06:59:07
问题 In python 2.7, I want to create a static variable which stores the result of running a static method of the enclosing class. I tried the following: class A: @staticmethod def foo(): return 1 v = A.foo() # a static variable print A.v which returns the error: NameError: name 'A' is not defined However, referring to another class' static variable works: class B: @staticmethod def foo(): return 1 class A: @staticmethod def foo(): return 1 v = B.foo() print A.v >>> 1 Any explanations? EDIT: The

Java中static、final用法小结

由 痴心易碎 提交于 2020-04-17 03:49:51
【推荐阅读】微服务还能火多久？>>> 一、final 1.final变量： 当你在类中定义变量时，在其前面加上final关键字，那便是说，这个变量一旦被初始化便不可改变，这里不可改变的意思对基本类型来说是其值不可变，而对于对象变量来说其引用不可再变。其 初始化 可以在两个地方，一是其 定义 处，也就是说在final变量定义时直接给其赋值，二是在 构造函数 中。这两个地方只能选其一，要么在定义时给值，要么在构造函数中给值，不能同时既在定义时给了值，又在构造函数中给另外的值。 当 函数参数为final 类型时，你可以读取使用该参数，但是无法改变该参数的值。 另外方法中的 内部类 在用到方法中的参变量时，此参变也必须声明为final才可使用 2.final方法 如果一个类不允许其子类覆盖某个方法，则可以把这个方法声明为final方法。 使用final方法的原因有二： 第一、把方法锁定，防止任何继承类修改它的意义和实现。 第二、高效。编译器在遇到调用final方法时候会转入内嵌机制，大大提高执行效率。 3.final类 final类不能被继承，因此final类的成员方法没有机会被覆盖，默认都是final的。在设计类时候，如果这个类不需要有子类，类的实现细节不允许改变，并且确信这个类不会载被扩展，那么就设计为final类。 二、static

What is the difference between static const int and static int const?

由 北战南征 提交于 2020-04-16 03:32:48
问题 In this answer the OP used: static int const var = 5; in the context of a Conditional Compilation Control. Is there a difference between using static const int and static int const ? Like for example: static const int var; vs. static int const var; I don´t know the technique to imply the type in the middle between static and const . Is there a difference? 回答1: The grammar for declaration specifiers is given in C 2018 6.7 1, and it shows that specifiers for storage class (such as static ),

Static member error with instance member, xUnit

由 不打扰是莪最后的温柔 提交于 2020-04-16 02:28:31
问题 "An object reference is required for the non-static field" I have a static member which cannot be an instance member. This static member uses an instance of an object that is initialized in the constructor of the class through dependency injection, so it cannot be static. How could I solve this error? public class My { private readonly Fixture _fixture; public MyClass(Fixture fixture) { _fixture = fixture; } public static IEnumerable<object[]> TestCases() { yield return new object[] { Urls

function won't change value of variable in java?

由 大憨熊 提交于 2020-04-13 07:57:46
问题 I know that everything in java is passed by value but shouldn't the below code print 2 instead of 1. All I am doing is passing Integer and changing its value. Why is it printing 1 instead of 2 ? public static Integer x; public static void doChange(Integer x) { x = 2; } public static void main(String arg[]) { x = 1; doChange(x); System.out.println(x); } 回答1: thank you so much for your answers. i think i know now what is happening under the hood. i think the reason i am not able to see changes

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
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