按照题目要求编写的Java程序如下
import java.util.Scanner
class RadiusException extends Exception{
public RadiusException(String message){
super(message)
}
}
public class Circle{
public double area(double r) throws RadiusException{
if(r<0)
throw new RadiusException("输入错误")
else
return Math.PI*r*r
}
public static void main(String[] args){
System.out.print("请输入圆的半径r:")
try{
Scanner sc=new Scanner(System.in)
double r=sc.nextDouble()
Circle c=new Circle()
System.out.println("圆的面积为"+c.area(r))
sc.close()
}catch(RadiusException re){
System.out.println(re.getMessage())
}
}
}
class GrandFather{private String name
private int age
public GrandFather(String name, int age){
this.name = name
this.age = age
}
public String getGrandFather(){
return (name + ":" +age)
}
}
class Father extends GrandFather{
private String occupation
public Father(String name, int age, String occupation){
super(name, age)
this.occupation = occupation
}
public String getFather(){
return super.getGrandFather() + " " +this.occupation
}
}
public class ClassMain{
public static void main(String[] args){
GrandFather gf = new GrandFather("Tom", 75)
Father f = new Father("Gim", 49, "orgnizer")
System.out.println(gf.getGrandFather())
System.out.println(f.getFather())
}
}
import java.util.ArrayListimport java.util.List
public class Random {
public static void main(String[] args) {
String[] tiMu = new String[20]
for (int i = 0 i < tiMu.length i++) {
tiMu[i] = "第" + (i + 1) + "题"
}
String[] temp = new String[10]
//开始抽取题目
//产生10个随机数
List<Integer> list = new ArrayList<Integer>()
int i
while(list.size() < 10){
i = (int) (Math.random() * 20)
if(!list.contains(i)){
list.add(i)
}
}
for (int j = 0 j < list.size() j++) {
temp[j] = tiMu[list.get(j)]
}
for (int iloop = 0 iloop < temp.length iloop++) {
System.out.print(temp[iloop] + " ")
}
}
}
代码已经写完了，亲测可用，望采纳哦！
