java课件overload重载在一个类中方法名相同参数个数顺序类型

This:当前对象自己，用于非静态的方法中。在构造方法的第一句调用另一个构造如何去调用一个构造：newSomeClassthis(..);Java.lang.Object-默认的，在object中的equalsclassStudprivateStringprivateintpublicStud(Stringname,intage)=this.age=}publicbooleanequals(Objectobj)if(this==obj)return}elseif(objinstanceofStud){Studother=(Stud)obj;if(.equals()&&this.age==other.age)return}elsereturn}}elsereturn}}}}再说*比较字符串的publicvoidtestString(){Stringstr1=Stringstr2=newbooleanboostr1.equals(str2);//String类重写了equals}Integer/Boolean/Double/String...都重写了equals-Animalaa=new}}class}classDogextends}publicclassDemo02{publicvoidtest1(){Animalaa=newDog();aa.eat();//如果dog没有重写eat方法，则只会调用父类的eat}}classpublicvoidSystem.err.println("animaliseating}}classDogextends}publicclassDemo02{publicvoidAnimal//数据类型aa//变量名 newDog();////eateat方法与newDogeat与dog}}classpublicvoidSystem.err.println("animaliseating}}classDogextendspublicvoidSystem.err.println("dogiseating }}-packageimportpublicclassDemo02{publicvoidAnimal//数据类型aa//变量名 newDog();////eateat方法与newDogeat与dog

System.err.println();//Animalaa.say();//Animal静态的方法与类型绑定-}}classpublicStringname=publicstaticvoidSystem.err.println("Animalis}publicvoidSystem.err.println("animaliseating}}classDogextendsAnimal{publicStringname="Dog";publicstaticvoidsay(){System.err.println("Dogis}publicvoidSystem.err.println("dogiseating }}packageimportpublicclassDemo03{publicvoidtest1(){Gradpag=newChild();g.song}}classpublicvoidSystem.err.println("gradpais }}classFatherextendsGradpa{publicvoidsong(){System.err.println("fatherissonging }}classChildextendspublicvoidsong(){System.err.println("childissonging...");}}publicclassDemo01{publicvoidtest1()BlackDogblackDog=new用dog指向blackdogDogdog=blackDog;Animalanimal=Dogdog2Dog)animal;//编译时出错，可以通过转换来实现BlackDogblackDog2=(BlackDog)animal;//转换Catcat=newCat();Animalanimal2=cat;Dogdog3Dog)animal2;//}}classAnimal}classDogextendsAnimal}classBlackDogextendsDog}classCatextendsAnimal}4：supersuper关键字表示的是父类的对象。classAnimalpublicStringname=}classDogextendsAnimalpublicStringname=publicvoidsay(){System.err.println("nameis:"+name);//使用superSystem.err.println(":}}packageimportpublicclassDemo02{publicvoidTwotwo=new}}classpublicOne(Stringname){}}classTwoextendspublicTwo()//可以使用super(..)}}1extends:继承的是父类的public/protected的成员变量+3：super5：从Object当一个对象进行字符串的++newpackageimportpublicclassDemo03{publicvoidtest1()Teachertt=new }}classTeacher{publicStringtoString()return o这是}}是指 class}1：不能使用new2：抽象类里面可以有抽象的方法-就是使 修饰的方法没有方法体class*publicvoid}* void}法class*publicvoid}* void}classDogextendsAnimal{publicvoideat()}}7接口用interfaceinterface}1：接口不能实例化即不能2:接口中的所有方法，默认都是public 3:接口中所有成员变量，默认都是publicstaticfinal的公开的静态的常量-必须要要时赋值4implementsinterfaceIAnimal{Stringname="Jerry";publicvoideat();}interfacepublicvoid}classDog1implementsIAnimal,IFood{publicvoideat()}publicvoidgood()}}}interfaceIAnimal{Stringname="Jerry";publicvoideat();}interfacepublicvoid}classDog1extendsDemo01implementsIAnimal,IFood{publicvoideat()}publicvoidgood()}}IAnimala1=newDog1();IFoodfood=newDog1();Demo01dd=newDog1();finalfinal-用final用final1：在时赋值或是在构造中赋值用finalstatic-1：在时赋值或是在静态的代码块赋值package直接在文件中的类，外部类或是叫顶层*@authorpublicclassDemo03classOne}publicvoidclassTwo{//}}}publicclassDemo03privateStringname=classOnepublicvoidaa(){}}publicvoidclassTwo{//publicvoidaa111(){}}}}packageimportimportimportpublicclassDemo04extendspublicDemo04()setTitle("第一个Java界面//给容器添加，用于用户的关闭//这个接口的实现classMyWindowListenerimplementspublicvoidwindowOpened(WindowEvente)}publicvoidwindowClosing(WindowEvente)}publicvoidwindowClosed(WindowEvente)}publicvoidwindowIconified(WindowEvente)}publicvo