第5讲-面向对象程序设计(3).ppt

抽象类与接口抽象类【例】抽象类举例。
abstractclassA{
abstractvoidcallme();
voidmetoo(){
System.out.println("InsideA'smetoo()method");
}
}

classBextendsA{
voidcallme(){
System.out.println("InsideB'scallme()method");
}
}

publicclassAbstract{
publicstaticvoidmain(Stringargs[]){
Ac=newB();
c.callme();
c.metoo();
}
}接口7891.接口的定义2.接口的实现【例】接口的实现：在类FIFOQueue中实现上面所定义的接口collection。
classFIFOQueueimplementscollection{
voidadd(Objectobj){
...
}
voiddelete(Objectobj){
...
}
Objectfind(Objectobj){
...
}
intcurrentCount{
...
}
}其他final关键字实例成员和类成员【例】实例成员举例
classAnIntergerNamedX{
intx;
publicintx(){
returnx;
}
publicvoidsetX(intnewX){
x=newX;
}
}类变量【例】类变量举例
classAnIntergerNamedX{
staticintx;
publicintx(){
returnx;
}
publicvoidsetX(intnewX){
x=newX;
}
}类方法【例】不正确的引用
classAnIntergerNamedX{
intx;
staticpublicintx(){
returnx;
}
staticpublicvoidsetX(intnewX){
x=newX;
}
}内嵌类publicclassStack{
privateVectoritems;
...//codeforStack'smethodsandconstructorsnotshown...
publicEnumerationenumerator(){
returnnewStackEnum();
}
classStackEnumimplementsEnumeration{
intcurrentItem=items.size()-1;
publicbooleanhasMoreElements(){
return(currentItem>=0);
}
publicObjectnextElement(){
if(!hasMoreElements())thrownewNoSuchElementException();
elsereturnitems.elementAt(currentItem--);
}
}
}28THEEND