第一类题目：1：public class exer {public static void main(String[] args) {int a=1+(int)(Math.random()*3000);boolean isprime=true;for(int k=2;k<=a/2;k++){if(a%k==0) isprime=false;break;}if(isprime) System.out.println(a+"是素数");else System.out.println(a+"不是素数");}}（2）public class exer {public static void main(String[] args) {for(int i=10000;i<=100000;i=i+10000){double sum=1;double e=1;for(int k=1;k<=i;k++){sum*=k;e+=1.0/sum;}System.out.println("当i的值为"+i+"时e的值为"+e);}}}（4）public class exer {public static void main(String[] args) {int[] a={1,4,7,9,12};for(int i=0;i<=2;i++){int temp;temp=a[i];a[i]=a[4-i];a[4-i]=temp;}for(int i=0;i<=4;i++){System.out.print(a[i]+" ");}}}第二类题目1：public class exer21 {public static void main(String[] args) {Triangle t=new Triangle(1,1.5,1);t.setcolor("yellow");t.setfilled(true);System.out.println(t.toString()+"\n周长为"+t.getPerimeter()+"\n面积为"+t.getArea()+"\n颜色为"+t.getcolor()+"\n是否填充 ："+t.getfilled()); }}abstract class GeometricObject{protected String color;protected boolean filled;;abstract public double getArea();abstract public double getPerimeter();}class Triangle extends GeometricObject{private double side1;private double side2;private double side3;public Triangle(){side1=1;side2=1;side3=1;}public Triangle(double side1,double side2,double side3){this.side1=side1;this.side2=side2;this.side3=side3;}public void setside1(double side1){this.side1=side1;}public double getside1(){return side1;}public void setside2(double side2){this.side2=side2;}public double getside2(){return side2;}public void setside3(double side3){this.side3=side3;}public double getside3(){return side3;}public void setcolor(String color){this.color=color;}public String getcolor(){return color;}public void setfilled(boolean filled){this.filled=filled;}public boolean getfilled(){return filled;}public double getArea() {double s=(sid...
