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【说明】 下面是一个Applet程序,程序的功能是在显示面板上输出字符串。当html页面被其他窗口遮挡后再次显示时,请给出输出结果。 import java.awt.*; import java. (1) . *; public class MyApplet (2) Applet { public void (3) (Graphics g) { g.drawString(tip,20,40); tip ="I am Java Applet"; } public void init() { tip ="welcome"; } private (4) tip; } <html> <head> <title> A Simple Applet </title> </head> <body> <applet code="MyApplet.class" width=800 height=400> </applet> </body> </html> 网页输出 (5)

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applet (2)extends (3)paint (4)String (5)I am Java Applet
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【说明】以下程序的功能是计算正方体、球体和圆柱体的表面积和体积并输出。程序由4个类组成:类cube、sphere和cylinder分别表示正方体、球体和圆柱体;抽象类 container为抽象类,提供了两个纯虚拟函数surface_area()和volum(),作为通用接口。【C++程序】#include<iostream.h> #define pi 3.1416class container{ protected: double radius; public:container(double radius) {container::radius=radius;}virtual double surface_area()=0;virtual double velum()=0;};class cube: (1) { 定义正方体类public:cube(double radius):container(radius){};double surface_area () {return 6 * radius * radius;}double volum() {return radius * radius * radius;}};class sphere: (2) { 定义球体类public:sphere(double radius): container(radius){};double surface_area() { return (3) ;}double volum() {return pi * radius * radius * radius * 4 3;}};class cylinder: (4) { 定义圆柱体类double height;public:cylinder(double radius,double height):container(radius){container::height=height;}double surface_are a () { return 2 * pi * radius * (height+radius); }double volum () {return (5) ;}};void main(){container * p;cube obj1 (5);sphere obj2(5);cylinder obj3(5,5);p=&obj1;cout<<“正方体表面积”(<<p->surface_area()<<end1;cont<<“正方体体积”<<p->volume()<<end1;p=&obj2;cout<<“球体表面积”<<p->surface_area()<<end1;cout<<“球体体积”<<p->volume()<<end1;p=&obj3;cout<<“球体表面积”<<p->surface_area()<<end1;cout<<“球体体积”<<p->volume()<<end1;}