结对编程，四则运算

package mirrorliAndhuangqi;


import java.lang.Math;
public class Operating {

//声明第一个操作数、第二个操作数、操作符、结果
private static int firstNum;
private static int secondNum;
private static String operator;
//private static int result;

//生成第一个操作数
public int firstNum(){
firstNum = (int)(1+Math.random()*99);//第一个操作数1~100
return firstNum;
}

//生成第二个操作数
public int secondNum(){
secondNum = (int)(1+Math.random()*99);//第二个操作数1~100
return secondNum;
}

//返回操作符
public String operator(){
int flag;
flag = (int)(1+Math.random()*3);//1~4分别对应+-*/
switch(flag){
case 1:
operator = "+";
break;
case 2:
operator = "-";
break;
case 3:
operator = "*";
break;
case 4:
operator = "/";
break;
default:
break;
}
return operator;
}

//返回结果
/* public int result(){
if(operator == "+"){
return firstNum+secondNum;
}else if(operator == "-"){
return firstNum-secondNum;
}else if(operator == "*"){
return firstNum*secondNum;
}else if(operator == "/"){
return firstNum/secondNum;
}else{
return 0;
}
}
*/
public String expression(){
return firstNum()+operator()+secondNum();
}

}

测试代码：

package mirrorliAndhuangqi;


public class Test {
public static void main(String[] args){
//存放30个表达式的字符数组
String expree[]=new String[30];
Operating opera = new Operating();
//将第一个随机表达式存入数组
expree[0]=opera.expression();
for(int i=1;i<30;i++){
//判断是否能跳出while循环
boolean flag = true;
//若有一个新表达式则加入数组并跳出循环
while(flag){
String str = opera.expression();
int gg = 0;
//遍历表达式数组expree，查重
for(int k=0;kif(str == expree[k]){
break; 
}else{
gg++;
}
}
//如果之前所有的都没重复则添加到数组
if(gg == i){
flag = false;
expree[i] = str;
}
}
}
for(int i=0;i<30;i++){
System.out.println(expree[i]+"=?");
}
//
}
}