Java基础教程3面向对象(下).ppt

public abstract class A { public abstract void aa(int x,int y); public void bb(int x ,int y){ System.out.println(method bb); } } class B extends A{ public void aa(int x,int y){ System.out.println(method aa); } public static void main(String[] args){ B b=new B(); } } public interface Runner { public int ID=1; public void run(); } ---------------------------------------------- public interface Animal extends Runner{ public void breathe(); } ---------------------------------------------- public class Fish implements Animal { public void breathe() { System.out.println(fish is bubbling); } public void run() { System.out.println(fish is swimming); } public static void main(String args[]){ Fish f= new Fish(); f.breathe(); f.run(); System.out.println(Runner.ID); System.out.println(Fish.ID); System.out.println(f.ID); } } ---------------------------------------------- public abstract class LandAnimal implements Animal{ public void breathe() { System.out.println(LandAnimal is breathing); } } public class A { public void func1() { System.out.println(A func1 is calling); } public void func2() { func1(); } } ------------------------------------------- class B extends A{ public void func1() { System.out.println(B func1 is calling); } public void func3() { System.out.println(B func3 is calling); } } ------------------------------------------- public class C { /** * @param args */ public static void main(String[] args) { B b=new B(); A a = b; //callA(a); callA(new A()); } public static void callA(A a) { //if(a instanceof B){ a.func1(); a.func2(); B b=(B)a; b.func3(); //} } } public class TestIOException { /** * @param args */ public static void main(String[] args) { try{ FileInputStream in =new FileInputStream(c:\\me.txt); int b; b=in.read(); while(b!=-1){ System.out.print((char)b); b=in.read(); } in.close(); }catch(Exception e){ System.out.println(e); } } } ------------------------------------------------