Static constructor function 

  Problems 

  1, in the tools category, there are usually no need to initialize the static method is called before, such as configuration information read 

  2, in the general category of the complex static information required in any case before the initialization method is called 

  I have seen solutions 

  1, in each of the static method call in all the necessary steps to initialize 

  (Public class SomeUtilClass 

  Private SomeUtilClass () ( 

  ) 

  Private static void Init () ( 

//….

  ) 

  Public static string GetUID () ( 

  Init (); 

  Return uid; 

  ) 

  Public static string GetConnectionString () ( 

  Init (); 

  Return connString; 

  ) 

  ) 

  2, in the general structure function initializes 

  (Public class SomeMapperClass 

  Private static Hashtable types; 

  Public SomeMapperClass () ( 

  If (types == null) ( 

  Types = new Hashtable (); 

  Types.Add ( "RED" Color.Red); 

  Types.Add ( "GREEN" Color.Green); 

  Types.Add ( "BLUE", Color.Blue); 

  ) 

  ) 

  Public Color GetColor (string color) ( 

  Return (Color) types [color]; 

  ) 

  ) 

  I recommend solutions 

  Using the static structure function (C #), or static initialization block (Java) 

  [C #] 

  (Public class SomeClass 

  Static SomeClass () ( 

  Init (); 

  Types = new Hashtable (); 

  Types.Add (…); 

  Types.Add (…); 

  ) 

  ) 

[Java]

  (Public class SomeClass 

  (Static 

  Init (); 

  Types = new HashMap (); 

  Types.put ( "", ""); 

  Types.put ( "", ""); 

  ) 

  ) 

  Effect 

  1, Once, only once 

  2, the definition of abnormal processing is required, reference can be standardized 

  2, multi-threaded, whether there is a problem, I do not know, talk about 

  CD-agent 

  Problems 

  There is a set internal targets, from the object to control the increase of its elements deleted, but customers need access to the pool is made of the information you want, and it is impossible for all target customers provide corresponding method, the need to return to the Internal set, but do not allow customers to add or delete elements 

  I have seen solutions 

  Set directly on behalf of the members return invoked only in the document can not require customers to set the element additions and deletions 

  (Public class SomeClass 

  Private List attrs; 

  Public List GetAttributes () ( 

  Return attrs; 

  ) 

  ) 

  I recommend solutions 

  1, the preferred language functions 

  2, the second best class library provided by the function 

  3, their packaging Agency, or return to the depth of copy, or use of AOP 

  [C + +] 

  Class config 

  ( 

  Public: 

  Const list <string> & get_attributes () ( 

  Return attrs; 

  ) 

  Private: 

  List <string> attrs; 

  ); 

  [C #] 

  (Public class SomeClass 

  Private IList attrs; 

  Public IList GetAttributes () ( 

  Return ArrayList.ReadOnly (attrs); 

  ) 

  ) 

[Java]

  (Public class SomeClass 

  Private List attrs; 

  Public List getAttributes () ( 

  Return Collections.unmodifiableList (attrs); 

  ) 

  ) 

  Effect 

  1, the language features can help compiler in the period of inspections, to ensure that the process of additions and deletions even elements of the code does not exist, but, intentionally or unintentionally, to the powerless transition const 

  2, class libraries provided by the features can help in the operation carried out checks to ensure that the process of additions and deletions to the operational elements are dished out anomalies 

  Synchronization Agent 

  Problems 

  Object to the introduction of a security thread synchronization mechanisms, has made object in a single-threaded environment, the performance of unnecessary costs, have examples such as writing copy COW 

  I have seen solutions 

  Is turning a blind eye, no treatment, the use of synchronization primitives 

  [C #] 

  (Public class SomeClass 

  [MethodImplAttribute (MethodImplOptions.Synchronized)] 

  Public void Add (string name) ( 

  Attrs.Add (name); 

  ) 

  ) 

[Java]

  (Public class SomeClass 

  Public synchronized void Add (string name) ( 

  Attrs.add (name); 

  ) 

  ) 

  I recommend solutions 

  The reference libraries, providing no synchronization primitive type, and the synchronization agent; JDK early in the Vector and HashTable are synchronized category, the new ArrayList and HashMap is not synchronized, Collections provide a static method returns synchronization Acting When in a multi-threaded environment necessary to change the set, the use of Agency 

  [C #, in a multi-threaded environment, the use of synchronous code Agent] 

  (Public class SomeClass 

  Public SomeClass (IList source) ( 

  Attrs = ArrayList.Synchronized (source); 

  ) 

  Public void Add (string name) ( 

  Attrs.Add (name); 

  ) 

  Public void Remove (string name) ( 

  Attrs.Remove (name); 

  ) 

  ) 

  [C #, single-threaded environment, the use of synchronous code Agent] 

  (Public class OtherClass 

  Public OtherClass (IList source) ( 

  Attrs = source; 

  ) 

  Public void Add (string name) ( 

  Attrs.Add (name); 

  ) 

  Public void Remove (string name) ( 

  Attrs.Remove (name); 

  ) 

  ) 

  [Java, in a multi-threaded environment, the use of synchronous code Agent] 

  (Public class SomeClass 

  Public SomeClass (List source) ( 

  Attrs = Collections.synchronizedList (source); 

  ) 

  Public void add (string name) ( 

  Attrs.add (name); 

  ) 

  ) 

  [Java, single-threaded environment, the use of synchronous code Agent] 

  (Public class OtherClass 

  Public OtherClass (List source) ( 

  Attrs = source; 

  ) 

  Public void add (string name) ( 

  Attrs.add (name); 

  ) 

  ) 

  Effect 

  Having the functions do not need to pay for additional costs 

  Problems 

  Sometimes need precise control over the allocation of resources and the timing of the release, ensuring that the resources of abnormal security, to avoid leakage of resources, resulting in deadlock, the paper loss, such as excessive database connection 

  I have seen solutions 

  In the absence of real objects and Analysis of the local structure function in the language, try / catch / finally flooding in the code 

  The use of middleware can help solve some of the resources management, such as database access 

  AOP may be based on the Resource Management Framework 

  I recommend solutions 

  In C + +, automated management of resources is born, that is, the BS "resource management is initialize" (RAII) 

  In C #, + can be used IDispose made using approximate the effect of RAII 

  In Java, I do not know, talk about 

  [C + +, RAII only examples, the paper should be the preferred operating std:: ftream, etc.] 

  Class File 

  ( 

  Public: 

  Explicit File (string path) ( 

  Pf = fopen (path.c_str (), "rwb"); 

  ) 

  ~ File () ( 

  Fclose (pf); 

  ) 

  Operator FILE * () ( 

  Return pf; 

  ) 

  Private: 

  FILE * pf; 

  ); 

  [C + +, the client code RAII only examples, the paper should be the preferred operating std:: ftream, etc.] 

  Void test () 

  ( 

  File file ( "auto.txt"); 

  Char buf [256]; 

  Fread (buf, 0, 256, file); / / Even if this operation will throw an error, the paper will still be closed 

  ) 

  [C #, just examples] 

  Public class File: IDisposable ( 

  Private FileStream fs; 

  Public File (string path) ( 

  Fs = new FileStream (path, FileMode.Create); 

  ) 

  Public static implicit operator FileStream (File file) ( 

  Return file.fs; 

  ) 

  Public void Dispose () ( 

  Fs.Close (); 

  ) 

  ) 

  [C #, just examples] 

  Public class Test ( 

  Void test () ( 

  Using (File file = new File ( "auto.txt")) ( 

  / / Some read, write, etc. 

  ) 

  / / Document has been closed, even dished out a further operation abnormal 

  ) 

  ) 

  Effect 

  1, resource management automation, is not confined to memory 

  2, the use of C + + templates, uniform definition of the packaging most of the resources of the current C # definition of resources only for each separate category, or use the AOP 

  Problems 

  Avoid memory leaks in Java 

  Solution 

  Discuss 

  [Reference: Recommended 

  1.C # standards: ECMA-334: C # Language Specification 

  2.Java standards: The Java? Language Specification Second Edition 

  3.C + + standard: ISO / IEC 14882:2003 Programming Languages - C + + 

  4.The C # Programming Language 

  5.The Java Programming Language 

  6.The C + + Programming Language