造福后辈攒人品带笔记课件chapter08.pdfVIP

Interfaces

•interfacea“pure”class.

–Allthemethodsare(withnames,argumentlists,andreturn

types,butwithoutmethodbodies).

–methodsimplicitlypublicand.

–Fields:implicitlystaticandfinal.

•Tocreateaninterface,

–usetheinterfacekeywordinsteadoftheclasskeyword.

–Likeaclass,aninterfacecanbedefinedaspublic(addthepublic

keywordbeforetheinterfacekeyword)

–orleaveitoffto“friendly”

•Tomakeaclassthatconformstoaparticularinterface(orgroup

ofinterfaces)usetheimplementskeyword.

•Theinterfaceismorethanjustanclasstakentothe

extreme,sinceitallowsyoutoperformavariationonC++’s

“multipleinheritance

Interfaces

importjava.util.*;

interfaceInstrument{

//Compile-timeconstant:

inti=5;//staticfinal

//Cannothavemethoddefinitions:

voidplay();//Automaticallypublic

Stringwhat();

voidadjust();

}

classWindimplementsInstrument{

publicvoidplay()

{System.out.println(Wind.play());}

publicStringwhat()

{returnWind;}

publicvoidadjust(){}

}

classPercussionimplementsInstrument｛

．．．．．．

}

classStringedimplementsInstrument{．．．．．．}

classBrastendsWind{

publicvoidplay(){System.out.println(Brass.play());}

publicvoidadjust(){System.out.println(Brass.adjust());}

}

classWoodwindextendsWind{．．．．．．}

publicclassMusic5{//Doesntcareabouttype,sonewtypes

//addedtothesystemstillworkright:

staticvoidtune(Instrumenti){i.play();}

staticvoidtuneAll(Instrument[]e){

for(inti=0;ie.length;i++)tune(e[i]);

}

publicstaticvoidmain(String[]args){