设计思想：

写一个生成四则运算的java类，封装起来，以便调用。四则运算的符号用死以内的随机数生成，1对应+，以此类推，用if语句控制结果在100以内。

开发中遇到的问题：

写三元运算的时候，把二元运算的代码直接复制了下来，结果只有两个操作数。

解决的方法：

重新写了代码，生成三元运算。

源代码：

public class BinaryAirthmetic {    private String firstOperation;    private String secondOperation;    private String character1;    private String character2;    public String getCharacter2() {        return character2;    }    public void setCharacter2(String character2) {        this.character2 = character2;    }    private int first;    private int second;    private int mid;    public int getMid() {        return mid;    }    public void setMid(int mid) {        this.mid = mid;    }    private String midOperation;        public String getMidOperation() {        return midOperation;    }    public void setMidOperation(String midOperation) {        this.midOperation = midOperation;    }    public String getFirstOperation() {        return firstOperation;    }    public void setFirstOperation(String firstOperation) {        this.firstOperation = firstOperation;    }    public String getSecondOperation() {        return secondOperation;    }    public void setSecondOperation(String secondOperation) {        this.secondOperation = secondOperation;    }    public String getCharacter1() {        return character1;    }    public void setCharacter1(String character1) {        this.character1 = character1;    }    public int getFirst() {        return first;    }    public void setFirst(int first) {        this.first = first;    }    public int getSecond() {        return second;    }    public void setSecond(int second) {        this.second = second;    }    private int result;    public int getResult() {        return result;    }    public void setResult(int result) {        this.result = result;    }}

mport java.util.ArrayList;import java.util.List;import java.util.Random;import BinaryAirthmetic.BinaryAirthmetic;public class MathProblem {    public static List
     
       Binary(int num,int yuan) {        List
      
        binaryAirthmetics=new ArrayList<>();                Random random=new Random();        int number=1;        int left=0;        int mid=0;        int right=0;        int c=0;        int c1;        int result=0;        String output="";        String output1="";        if(yuan==2) {        for ( int i = 1; i <= 5000; i++ ) {            BinaryAirthmetic binaryAirthmetic=null;             // left = 1+random.nextInt(20);            // right=1+random.nextInt(20);             c=1 + (int) ( Math.random() * 4 );             switch(c){             case 1:{  left = 1+random.nextInt(20);             right=1+random.nextInt(20);             output="+";result=left+right;break;}             case 2:{ left = 1+random.nextInt(20);             right=1+random.nextInt(20);             output="-";result=left-right;break;}             case 3:{ left = 1+random.nextInt(9);             right=1+random.nextInt(9);             output="×";result=left*right;break;}             case 4:{ left = 1+random.nextInt(9);             right=1+random.nextInt(9);             output="÷";result=left/right;break;}                          }            if(result<=100&&number<=num&&result>=0&&(left%right==0)){                number++;                binaryAirthmetic=new BinaryAirthmetic();                binaryAirthmetic.setFirst(left);                binaryAirthmetic.setSecond(right);                binaryAirthmetic.setCharacter1(output);                binaryAirthmetic.setResult(result);                binaryAirthmetics.add(binaryAirthmetic);        }                    }                    }else {        for ( int i = 1; i <= 5000; i++ ) {            BinaryAirthmetic binaryAirthmetic=null;               left = 1+random.nextInt(20);             mid=1+random.nextInt(20);             right=1+random.nextInt(20);             c=1 + (int) ( Math.random() * 2 );                          switch(c){             case 1:{output="+";break;}             case 2:{output="-";break;}             }             c1=1 + (int) ( Math.random() * 2 );             switch(c1){             case 1:{output1="+";break;}             case 2:{output1="-";break;}             }             if(c==1&&c1==1) {                 result=left+mid+right;             }             if(c==1&&c1==2) {                 result=left+mid-right;             }             if(c==2&&c1==1) {                 result=left-mid+right;             }             if(c==2&&c1==2) {                 result=left-mid-right;             }            if(result<=100&&number<=num&&result>=0&&(left-mid)>=0){                number++;                binaryAirthmetic=new BinaryAirthmetic();                binaryAirthmetic.setFirst(left);                binaryAirthmetic.setMid(mid);                binaryAirthmetic.setSecond(right);                binaryAirthmetic.setCharacter1(output);                binaryAirthmetic.setCharacter2(output1);                binaryAirthmetic.setResult(result);                binaryAirthmetics.add(binaryAirthmetic);        }         }    }        return binaryAirthmetics;}}
      
     

<%@ page language="java" contentType="text/html; charset=utf-8"    pageEncoding="utf-8"%><% session.setAttribute("time", 10); %>
        
       
     
        
        
        
        
        
选择题的数目(范围1~100)  
 选择几元运算(范围2~3)  
       
       
        

<%@page import="java.util.List"%><%@page import="BinaryAirthmetic.BinaryAirthmetic"%><%@ page language="java" contentType="text/html; charset=utf-8"    pageEncoding="utf-8"%>    <%char c='a';int i=1;int yuan=(int)session.getAttribute("yuan");String string1="对";String string2="错";String s;String string;List
     
       binaryAirthmetics=(List
      
       )session.getAttribute("binary");%>
       
         
       
       
        
         
                <%      if(yuan==2){   for(BinaryAirthmetic binaryAirthmetic:binaryAirthmetics) {             //s=String.valueOf(c);       string=Integer.toString(i, 1000);      if("".equals(request.getParameter(string).trim()))      {              %>
<%i++;continue; } %> <% if(binaryAirthmetic.getResult()==Integer.parseInt(request.getParameter(string).trim())){%>
<% }else{ %> 
 <% }%><%c++;i++; } } %> <% if(yuan==3){ for(BinaryAirthmetic binaryAirthmetic:binaryAirthmetics) { //s=String.valueOf(c); string=Integer.toString(i, 1000); if("".equals(request.getParameter(string).trim())) { %>
<%i++;continue; } %> <% if(binaryAirthmetic.getResult()==Integer.parseInt(request.getParameter(string).trim())){%>
<% }else{ %> 
 <% }%><%c++;i++; } } %> <% if(yuan!=2&&yuan !=3){ out.print("请输入2或者3"); } %> 
 <% out.println(binaryAirthmetic.getFirst()+binaryAirthmetic.getCharacter1()+binaryAirthmetic.getSecond()+"="+binaryAirthmetic.getResult()); out.println("你的结果:无"); %> 
 <% out.println(binaryAirthmetic.getFirst()+binaryAirthmetic.getCharacter1()+binaryAirthmetic.getSecond()+"="+binaryAirthmetic.getResult()); out.println("你的答案:"+request.getParameter(string)+"结果:正确"); %> 
 <%out.println(binaryAirthmetic.getFirst()+binaryAirthmetic.getCharacter1()+binaryAirthmetic.getSecond()+"="+binaryAirthmetic.getResult()); out.println("你的答案:"+request.getParameter(string)+"结果:错误"); %> 
 <% out.println(binaryAirthmetic.getFirst()+binaryAirthmetic.getCharacter1()+binaryAirthmetic.getMid()+binaryAirthmetic.getCharacter2()+binaryAirthmetic.getSecond()+"="+binaryAirthmetic.getResult()); out.println("你的结果:无"); %> 
 <% out.println(binaryAirthmetic.getFirst()+binaryAirthmetic.getCharacter1()+binaryAirthmetic.getMid()+binaryAirthmetic.getCharacter2()+binaryAirthmetic.getSecond()+"="+binaryAirthmetic.getResult()); out.println("你的答案:"+request.getParameter(string)+"结果:正确"); %> 
 <%out.println(binaryAirthmetic.getFirst()+binaryAirthmetic.getCharacter1()+binaryAirthmetic.getMid()+binaryAirthmetic.getCharacter2()+binaryAirthmetic.getSecond()+"="+binaryAirthmetic.getResult()); out.println("你的答案:"+request.getParameter(string)+"结果:错误"); %> 
       
      
     

<%@page import="javax.websocket.Session"%><%@page import="Database.DatabaseConnection"%><%@page import="BinaryAirthmetic.BinaryAirthmetic"%><%@page import="java.util.List"%><%@page import="MathProblem.MathProblem"%><%@ page language="java" contentType="text/html; charset=utf-8"    pageEncoding="utf-8"%><%int num=Integer.parseInt(request.getParameter("num"));int yuan=Integer.parseInt(request.getParameter("yuan"));int i=1;int number=1;MathProblem mathProblem=new MathProblem();List
     
       binaryAirthmetics=mathProblem.Binary(num, yuan);   DatabaseConnection databaseConnection=new DatabaseConnection();   databaseConnection.addDatabase(num, yuan,binaryAirthmetics);   char a='a';   session.setAttribute("binary", binaryAirthmetics);   session.setAttribute("yuan", yuan);      int time=(int)session.getAttribute("time");%> 
      时间还剩下:
      0分钟。10分钟秒后系统自动提交。
        
      
      
       
        
         
          <%   if(yuan==2){   for(BinaryAirthmetic binaryAirthmetic:binaryAirthmetics) {            String s=Integer.toString(i, 1000);%>
<% a++;i++;number++; } %> <% }%><% if(yuan==3){ for(BinaryAirthmetic binaryAirthmetic:binaryAirthmetics) { String s=Integer.toString(i, 100);%>
<% a++;i++;number++; } %> <% }%>
 <%=number+"."+"\r\r"+binaryAirthmetic.getFirst()+binaryAirthmetic.getCharacter1()+binaryAirthmetic.getSecond()+"=" %> > 
 <%=number+"."+"\r\r"+binaryAirthmetic.getFirst()+binaryAirthmetic.getCharacter1()+binaryAirthmetic.getMid()+binaryAirthmetic.getCharacter2()+binaryAirthmetic.getSecond()+"=" %> > 
<%if(yuan!=2&&yuan!=3){ out.print("元数请选择二元或者三元"); }%>
        
      
     

运行结果截图：