泛型基本知识.ppt

数据结构（Java版）,北京信息科技大学计算机学院段瑞雪,1,2,泛型,3,1publicclassGenericTest2publicstaticvoidmain(Stringargs)3Listlist=newArrayList();4list.add(qqyumidi);5list.add(corn);6list.add(100);78for(inti=0;ilist.size();i+)9Stringname=(String)list.get(i);/110System.out.println(name:+name);111213,Integer.parseInt(String),程序实现源码,泛型,泛型，即“参数化类型”。顾名思义，就是将类型由原来的具体的类型参数化，类似于方法中的变量参数，此时类型也定义成参数形式（可以称之为类型形参），然后在使用/调用时传入具体的类型（类型实参）。一般用T表示。,4,5,1publicclassGenericTest223publicstaticvoidmain(Stringargs)4/*5Listlist=newArrayList();6list.add(qqyumidi);7list.add(corn);8list.add(100);9*/1011Listlist=newArrayList();12list.add(qqyumidi);13list.add(corn);14/list.add(100);/1提示编译错误1516for(inti=0;ilist.size();i+)17Stringname=list.get(i);/218System.out.println(name:+name);192021,publicclassListBooleanadd(Tkey);Tget(Tkey);Tset(Tkey);.,6,自定义泛型接口、泛型类和泛型方法,7,publicclassBoxprivateintt;publicvoidset(intt)this.t=t;publicintget()returnt;,8,publicclassBoxprivatefloatt;publicvoidset(floatt)this.t=t;publicfloatget()returnt;,9,publicclassBoxprivateTt;publicvoidset(Tt)this.t=t;publicTget()returnt;,泛型类,10,publicclassBoxprivateTt;publicvoidset(Tt)this.t=t;publicTget()returnt;,publicstaticvoidmain(Stringargs)BoxintegerBox=newBox();BoxstringBox=newBox();integerBox.set(newInteger(10);stringBox.set(newString(菜鸟教程);System.out.printf(整型值为:%dnn,integerBox.get();System.out.printf(字符串为:%sn,stringBox.get();,为什么引入泛型的概念?1.类型检查。2.节省空间，一个泛型类，可以处理各种数据类型的数据。,11,12,ADTSet数据：集合中的数据元素，数据元素的数据类型为T操作booleanisEmpty();intsize();Tsearch(Tkey);booleancontains(Tkey);booleanadd(Tx);Tremove(Tkey);voidclear();booleancontainsAll(Setset);booleanaddAll(Setset);,13,接口,14,声明一个接口（最简单的情况）,15,接口的实际应用,16,interfaceUSB/操作标准publicvoidinstall();publicvoidwork();,classComputerpublicvoidplugin(USBusb)usb.install();usb.work();,classPhoneimplementsUSBpublicvoidinstall()System.out.println(安装手机驱动程序。);publicvoidwork()System.out.println(手机与电脑进行工作。);,classPrinterimplementsUSBpublicvoidinstall()System.out.println(安装打印机驱动程序。);publicvoidwork()System.out.println(进行文件打印。);,classMP3implementsUSBpublicvoidinstall()System.out.println(安装MP3驱动程序。);publicvoidwork()System.out.println(进行MP3拷贝。);,publicclassTestDemopublicstaticvoidmain(Stringargs)Computerc=newComputer();c.plugin(newPhone();c.plugin(newPrinter();c.plugin(newMP3();,为什么要引入接口的概念?1.减少重复定义。2.便于利用基类引用，处理各种类型的子类，实现多态。,17,18,接口和泛型,19,publicinterfaceSet泛型接口publicclassSortSetimplementsSetSetset=newSortSet();set.add(x),泛型通配符,T是类型参数，指定元素的数据类型，T的实际参数类型是类，在声明和创建对象时指定。“?”是泛型通配符，“？extendsT”是指T及其任意一个子类。“?superT”是指T及其任意一个父类。,20,21,泛型中占位符T和?有什么区别?,22,publicclassTeacherpublicStringstr;publicintage;publicintsex;publicTeacher(Stringstr,intage,intsex)this.str=str;this.age=age;this.sex=sex;,publicclassStudentextendsTeacherpublicStudent(Stringstr,intage,intsex)super(str,age,sex);,publicclassChildextendsStudentpublicChild(Stringstr,intage,intsex)super(str,age,sex);,Teacher,Student,Child,23,publicstaticvoidtest()ArrayListlist1=newArrayList();list1.add(newStudent(zhangsan,18,0);list1.add(newStudent(lisi,28,0);list1.add(newStudent(wangwu,24,1);/这里如果add(newTeacher(.);就会报错，show1(list1);/这里我们并没有给List指定具体的数据类型，/可以存放多种类型数据,publicstaticvoidshow1(Listlist)for(Objectobject:list)System.out.println(object.toString();,24,publicstaticvoidtest2()/这里我们并没有给List指定具体的数据类型，/可以存放多种类型数据ArrayListlist2=newArrayList();list2.add(newStudent(zhaoliu,22,1);list2.add(newTeacher(sunba,30,0);show2(list2);,publicstaticvoidshow2(Listlist)for(Objectobject:list)System.out.println(object);,25,publicstaticvoidtest3()ArrayListlist3=newArrayList();list3.add(newTeacher(zhaoliu,22,1);list3.add(newTeacher(sunba,30,0);show3(list3);/这里我们并没有给List指定具体的数据类型，/可以存放多种类型数据,publicstaticvoidshow3(Listlist)for(Objectobject:list)System.out.println(object);,26,publicstaticvoidtest3()/这里我们并没有给List指定具体的数据类型，/可以存放多种类型数据ArrayListlist4=newArrayList();list4.add(newStudent(sunba,30,0);list4.add(newTeacher(zhaoliu,22,1);show4(list4);,publicstaticvoidshow4(Listlist)for(Objectobject:list)System.out.println(object);,27,publicstaticvoidtest3()ArrayListlist5=newArrayList();list5.add(newChild(zhangsan,15,1);list5.add(newChild(sunba,30,0);list5.add(newChild(zhaoliu,22,1);show3(list5);ArrayListlist6=newArrayList();list6.add(newChild(zhangsan,15,1);list6.add(newStudent(sunba,30,1)