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1. 静态构造函数
C#中有静态构造函数， Java中没有静态构造函数。其实Java中有一个类似静态构造函数的东东，称作静态初始化，或者静态代码块，可以通过这样的代码实现相同的功能：
但是Java中静态代码块和C#静态构造函数还是不一样的。C#中静态构造函数在其他静态成员初始化后再执行，而java中静态代码块和其他静态成员谁在先谁就先执行。
1 class Parent{ 2 public static StaticVariable staticVariable = new StaticVariable("Parent - Static Variable1"); 3 public StaticVariable inStaticVariable = new StaticVariable("Parent - Instant Variable1"); 4 5 static 6 { 7 System.out.println("Parent - Static block/constructor"); 8 System.out.println(staticVariable == null); 9 //System.out.println(staticVariable2 == null); not working because staticVariable2 is not defined 10 staticVariable2 = new StaticVariable("Parent - Static Variable2 - Static block"); 11 } 12 13 { 14 System.out.println("Parent - Initializer Block"); 15 } 16 17 public static StaticVariable staticVariable2 = new StaticVariable("Parent - Static Variable2"); 18 public StaticVariable inStaticVariable2 = new StaticVariable("Parent - Instant Variable2"); 19 20 public Parent() 21 { 22 System.out.println("Parent - Instance Constructor"); 23 } 24 }
1 class StaticDemo 2 { 3 static int i = 1; 4 5 static StaticDemo() 6 { 7 Console.WriteLine(i); 8 Console.WriteLine(j); 9 } 10 11 public static void Execute() 12 { 13 } 14 15 static int j = 1; 16 }
2常量
Java中声明(实例/类)常量使用关键词(final/static final)。C#中声明(实例/类)常量使用关键词(readonly/const 或者 readonly static).
C#中必须使用类名去访问类层级的变量。Java中可以使用实例去访问类层级的变量，但是编译时会有警告。
Java Code and C# Code
1 class ParentDef{ 2 public static final String STATICVALUE_STRING="Parent Static Variable"; 3 public String valueString="Parent Instant Variable"; 4 } 5 6 class ChildRef extends ParentDef{ 7 public static final String STATICVALUE_STRING="Child Static Variable"; 8 public String valueString="Child Instant Variable"; 9 } 10 11 public class BasicDemo { 12 public static void main(String[] args) { 13 //Child child = new Child(); 14 15 ParentDef pdf = new ParentDef(); 16 ParentDef pcdf = new ChildRef(); 17 ChildRef cdf = new ChildRef(); 18 System.out.println("V1"); 19 System.out.println(pdf.STATICVALUE_STRING); 20 System.out.println(pdf.valueString); 21 22 System.out.println("V2"); 23 System.out.println(pcdf.STATICVALUE_STRING); 24 System.out.println(pcdf.valueString); 25 26 System.out.println("V3"); 27 System.out.println(cdf.STATICVALUE_STRING); 28 System.out.println(cdf.valueString); 29 30 } 31 32 }
1 class InheritenceDemo 2 { 3 public static void Execute() 4 { 5 ParentDef pdf = new ParentDef(); 6 ParentDef pc = new ChildDef(); 7 ChildDef cdf = new ChildDef(); 8 9 10 Console.WriteLine("V1"); 11 Console.WriteLine(pdf.value); 12 13 14 Console.WriteLine("V2"); 15 Console.WriteLine(pc.value); 16 17 Console.WriteLine("V3"); 18 Console.WriteLine(cdf.value); 19 Console.WriteLine(cdf.READONLYSTRING); 20 21 } 22 } 23 24 class ParentDef 25 { 26 public const string Const_String = "Parent Const Varialbe"; 27 public static string STATICVALUE_STRING = "Parent Static Variable"; 28 public string value = "Parent Instant Variable"; 29 } 30 31 class ChildDef:ParentDef 32 { 33 public readonly string READONLYSTRING="Child readonly variable"; 34 public readonly static string READONLYSTATICSTRING = "Child readonly static variable"; 35 public static string STATICVALUE_STRING = "Child Static Variable"; 36 public string value = "Child Instant Variable"; 37 38 public ChildDef() 39 { 40 READONLYSTRING = "NEW Child readonly variable"; 41 //READONLYSTATICSTRING = "NEW Child readonly static variable"; ERROR as satatic readonly variable can not be reassianged in instant constructor 42 } 43 }
3参数传递
C#中有ref关键词用来按引用传递参数。Java则没有，无法真正按引用传递参数。Java总是采用按值调用。方法得到的是所有参数值的一个拷贝，特别的，方法不能修改传递给它的任何参数变量的内容。
（1）：“在Java里面参数传递都是按值传递”这句话的意思是：按值传递是传递的值的拷贝，按引用传递其实传递的是引用的地址值，所以统称按值传递。
（2）：在Java里面只有基本类型和按照下面这种定义方式的String是按值传递，其它的都是按引用传递。就是直接使用双引号定义字符串方式：String str = “Java”;
C# code
class RefExample { static void Method(ref int i) { i = 44; } static void Main() { int val = 0; Method(ref val); // val is now 44 } }
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原文地址：http://www.cnblogs.com/1zhk/p/5054620.html
