Java8引入了默认方法的概念。考虑以下带有默认方法的接口(interface):publicinterfaceIDefaultMethod{publicabstractvoidmusImplementThisMethod();publicdefaultvoidmayOrMayNotImplementThisMethod(){System.out.println("Thismethodisoptionalforclassesthatimplementthisinterface");}}还有一个实现这个接口(interface)的类:publicclassDefaultMethodImp

这是一个编译时没有警告的程序，例如GNUC++:$g++-ot-Wall-pedantic-Wshadowt.cpp$./t.exeCallingbarney::barney()Callingfoo::operator()()Callingbarney::barney()但它在MSVC++上完全无法编译:$cl/EHsct.cppMicrosoft(R)32-bitC/C++OptimizingCompilerVersion15.00.30729.01for80x86Copyright(C)MicrosoftCorporation.Allrightsreserved.t.cppt.cp