Generic programming---Definition of generic classes

Generic programming, programming all understand what meaning, that generics? What is a generic type?

The so-called generic refers to: the amount ... Well, I don't know. For example: There is a sentence in ancient religious Taoism, Daosh One, life two, two three, Sansheng everything. The Tao here corresponds to the generic type in the program design, the generics are very abstract, I can not say why ... (You can leave a message under the article to discuss)

So how do you define a generic class?

The syntax is as follows:

Before you look at the syntax, you need to understand the concept of type variables. The so-called type variable refers to: can replace any type of a variable, when defined, you can use the character (general capitalization, and general use of T and its adjacent characters); Actually, when declaring a variable of a generic class, you need to use a specific class name instead of a type variable.

Class name < type variable ...;: type variable can have multiple, each type variable is separated by a comma ",".

The following is an example of a generic class program with 1 type variables and multiple type variables:

/*** dateandtime:2016-12-14 pm 10:15:03*/ PackageChapter12;/*** Test: definition of a generic class of 1 type variables *@authorAdministrator **/ Public classGenerictypeclass { Public Static voidMain (string[] args) {string[] words= {"Mary", "had", "a", "little", "lamb"}; Pair<String> pair =Arrayarg.minmax (words); System.out.println ("min:" +Pair.getfirst ()); System.out.println ("Max:" +Pair.getsecond ()); }}/*** A GenericType Class *@authorAdministrator * *@param<T>*/classPair<t> {        PrivateT first; PrivateT Second; Pair () { This. First =NULL;  This. Second =NULL; } Pair (t first, T second) { This. First =First ;  This. Second =second; }         PublicT GetFirst () {returnFirst ; }     Public voidSetfirst (T first) { This. First =First ; }     PublicT Getsecond () {returnsecond; }     Public voidSetsecond (T second) { This. Second =second; }    }classArrayarg { Public StaticPair<string>Minmax (string[] t) {if(NULL= = T | | T.length = = 0)return NULL; String min= T[0]; String Max= T[0];  for(String element:t) {if(Element.compareto (min) < 0) min =element; if(Element.compareto (max) > 0) max =element; }        return NewPair<>(min, max); }    }

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/*** dateandtime:2016-12-14 pm 10:36:44*/ PackageChapter12;/*** Definitions of generic classes for multiple types of variables *@authorAdministrator **/ Public classGenericTypeClass2 { Public Static voidMain (string[] args) {pairmultitypeparamters<string, integer> pmtp =Newpairmultitypeparamters<> ("Hello", 0); System.out.println ("T:" +Pmtp.getfirst ()); System.out.println ("U:" +Pmtp.getsecond ()); }}classPairmultitypeparamters<t, u> {    PrivateT first; PrivateU Second; Pairmultitypeparamters () { This. First =NULL;  This. Second =NULL; } pairmultitypeparamters (T First, U second) { This. First =First ;  This. Second =second; }         PublicT GetFirst () {return  This. First; }         Public voidSetfirst (T first) { This. First =First ; }         PublicU Getsecond () {return  This. Second; }         Public voidSetsecond (U second) { This. Second =second; }    }

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Generic programming---Definition of generic classes