In Java, if NULL and NULL are encountered, use optional to resolve the situation.

If null and empty are encountered in Java, use optional to resolve

Example code:

1  PackageCrazy;2 3 Importjava.util.Optional;4 5 classCompany {6     PrivateString name;7     PrivateOptional<office>Office;8 9      PublicCompany (String name, optional<office>Office) {Ten          This. Name =name; One          This. Office =Office; A     } -  -      PublicString GetName () { the         returnname; -     } -  -      PublicOptional<office>Getoffice () { +         returnOffice; -     } + } A  at classOffice { -     PrivateString ID; -     PrivateOptional<address>address; -  -      PublicOffice (String ID, optional<address>address) { -          This. ID =ID; in          This. Address =address; -     } to  +      PublicString getId () { -         returnID; the     } *  $      PublicOptional<address>getaddress () {Panax Notoginseng         returnaddress; -     } the } +  A classAddress { the     PrivateOptional<string>Street; +     PrivateOptional<string>City ; -  $      PublicAddress (Optional<string> Street, optional<string>City ) { $          This. Street =Street; -          This. City =City ; -     } the  -      PublicOptional<string>Getstreet () {Wuyi         returnStreet; the     } -  Wu      PublicOptional<string>getcity () { -         returnCity ; About     } $ } -  -  Public classOptionalDemo1 { -  A      Public Static voidMain (string[] args) { +optional<address> Address1 = Optional.of (NewAddress (Optional.ofnullable (NULL), Optional.of ("New York"))); theoptional<office> Office1 = Optional.of (NewOffice ("OF1", Address1)); -optional<company> company1 = Optional.of (NewCompany ("Door never Closed", Office1)); $  the         //What is the street address of Company1? the         //In which city Company1 is located? theOptional<office> Maybeoffice =Company1.flatmap (company::getoffice); theOptional<address> maybeaddress =Office1.flatmap (office::getaddress); -Optional<string> Maybestreet =Address1.flatmap (address::getstreet); in  the maybestreet.ifpresent (system.out::p rintln); the         if(Maybestreet.ispresent ()) { About System.out.println (Maybestreet.get ()); the}Else { theSystem.out.println ("Street not found.")); the         } +          -         //Shorter theString City =Company1.flatmap (Company::getoffice)Bayi . FlatMap (office::getaddress) the . FlatMap (Address::getstreet) the. OrElse ("City was not found."); -          -System.out.println ("City:" +City ); the          the          //Only print if city isn't null the Company1.flatmap (Company::getoffice) the . FlatMap (office::getaddress) - . FlatMap (address::getcity) the . Ifpresent (system.out::p rintln); the  the     }94}

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Welcome attention: A Amumu

In Java, if NULL and NULL are encountered, use optional to resolve the situation.