Comparable and comparator of a property comparison sort for an object in a Java collection

There are two ways to sort an attribute of an object in a collection.

A. One is to sort the object class to implement the comparable interface CompareTo method, then put the object into the list, and then call Collections.sort (list);
B. One is not to make any changes to the Sort object class, create the implementation class C of the comparator interface, then put the object into list, then call Collections.sort (list, C);

A.eg

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1  Public classUserImplementsComparable<user>{2     PrivateString name;3     Private intAge ;4     Private intgender;5     PrivateString address;6     7      PublicString GetName () {8         returnname;9     }Ten      One      Public voidsetName (String name) { A          This. Name =name; -     } -      the      Public intGetage () { -         returnAge ; -     } -      +      Public voidSetage (intAge ) { -          This. Age =Age ; +     } A      at      Public intGetgender () { -         returngender; -     } -      -      Public voidSetgender (intgender) { -          This. Gender =gender; in     } -      to      PublicString getaddress () { +         returnaddress; -     } the      *      Public voidsetaddress (String address) { $          This. Address =address;Panax Notoginseng     } -      the      PublicUser () { +         Super(); A     } the      +      PublicUser (String name,intAgeintgender, String address) { -         Super(); $          This. Name =name; $          This. Age =Age ; -          This. Gender =gender; -          This. Address =address; the     } -    Wuyi  the @Override -      Public intcompareTo (User o) { Wu         if(o!=NULL){ -             if( This. Getage () >O.getage ()) { About  $                return1; -}Else if( This. getage () = =O.getage ()) { -  -                return0; A  +             } the  -        } $         return-1; the     } the}

-------------------------------------------Main

1List<user> ulist =NewArraylist<user>();2Ulist.add (NewUser ("Wangbo", 29, 1, "Changsha"));3Ulist.add (NewUser ("Wumei", 44, 1, "Zhuzhou"));4Ulist.add (NewUser ("Zhangjie", 19, 1, "Yueyang"));5Ulist.add (NewUser ("Lihua", 36, 1, "Changsha"));6Ulist.add (NewUser ("Zhangchangzhe", 19, 1, "Hengyang"));7 8 Collections.sort (list);9 Ten  for(User u:ulist) { OneSystem.out.println (U.getname () + "\ T" +u.getage () + "\ T" +u.getaddress ()); A } -  -  

==============================================

B.eg

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1  Public classUser {2     PrivateString name;3     Private intAge ;4     Private intgender;5     PrivateString address;6     7      PublicString GetName () {8         returnname;9     }Ten      One      Public voidsetName (String name) { A          This. Name =name; -     } -      the      Public intGetage () { -         returnAge ; -     } -      +      Public voidSetage (intAge ) { -          This. Age =Age ; +     } A      at      Public intGetgender () { -         returngender; -     } -      -      Public voidSetgender (intgender) { -          This. Gender =gender; in     } -      to      PublicString getaddress () { +         returnaddress; -     } the      *      Public voidsetaddress (String address) { $          This. Address =address;Panax Notoginseng     } -      the      PublicUser () { +         Super(); A     } the      +      PublicUser (String name,intAgeintgender, String address) { -         Super(); $          This. Name =name; $          This. Age =Age ; -          This. Gender =gender; -          This. Address =address; the     } -     Wuyi } the  -  

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1 ImportJava.util.Comparator;2 3  Public classComparatorimplImplementsComparator<user>{4 5 @Override6      Public intCompare (user O1, user O2) {7         8         if(NULL!=o1 &&NULL!=O2) {9             if(O1.getage () >O2.getage ()) {Ten                 return1; One}Else if(O1.getage () = =O2.getage ()) { A                 return0; -             } -         } the         return-1; -     } -  -}

-----------------------------------Main

1List<user> ulist =NewArraylist<user>();2Ulist.add (NewUser ("Wangbo", 29, 1, "Changsha"));3Ulist.add (NewUser ("Wumei", 44, 1, "Zhuzhou"));4Ulist.add (NewUser ("Zhangjie", 19, 1, "Yueyang"));5Ulist.add (NewUser ("Lihua", 36, 1, "Changsha"));6Ulist.add (NewUser ("Zhangchangzhe", 19, 1, "Hengyang"));7Collections.sort (Ulist,NewComparatorimpl ());8          for(User u:ulist) {9System.out.println (U.getname () + "\ T" +u.getage () + "\ T" +u.getaddress ());Ten}

Comparable and comparator of a property comparison sort for an object in a Java collection