Arithmetic Upgrade 2

ImportJava.util.*; Public classFirst { Public Static voidMain (string[] agrs) {Doublea,b,c,d; intCount1=0,count2=0; inti; String[] s={"+","-","*","/"}; Scanner SC=NewScanner (system.in); intop= 0;  while(true) {System.out.println ("Select function: \n0. Exit 1. Simple subtraction operation 2. Compound Operation 3. With true fractional operation"); Op=Sc.nextint (); if(0 = = op) { Break;} if(1 = =op) {System.out.println ("(5 points/way) Please enter the number of questions:"); intn=Sc.nextint (); System.out.print ("Please enter the range of arithmetic (from small to Large):"); intmin=Sc.nextint (); intmax=Sc.nextint (); if(min>max) {System.out.print ("Input Error");  Break; } Random R=NewRandom ();  for(i=0;i<n;i++) {a=r.nextint (max)% (max-min+1) +min; b=r.nextint (max)% (max-min+1) +min; intL= R.nextint (s.length);//random number, less than the length of the array, 0~3System.out.print (A+S[L]+B);//Print Random charactersSystem.out.print ("="); DoubleA=sc.nextdouble (); if("+"==S[l]) {                                if(a==a+b) {System.out.println ("This is right!"); Count1++; }                                Else{System.out.println ("This is wroing!" + "The correct answer is:" + (A +b)); Count2++; }                         }                         Else if("-"==S[l]) {                             if(A-B) >-11){                                    if(a==a-b) {System.out.println ("This is right!"); Count1++; }                                    Else{System.out.println ("This is wroing!" + "The correct answer is:" + (A-b)); Count2++; }                             }                             Else{a=r.nextint (max)% (max-min+1) +min; b=r.nextint (max)% (max-min+1) +min; if(a==a-b) {System.out.println ("This is right!"); Count1++; }                                 Else{System.out.println ("This is wroing!" + "The correct answer is:" + (A-b)); Count2++; }                               }                            }                         Else if("*"==S[l]) {                             if(a==a*b) {System.out.println ("This is right!"); Count1++; }                             Else{System.out.println ("This is wroing!" + "The correct answer is:" + (A *b)); Count2++; }                         }                         Else if("/"==S[l]) {                             if(a==a/b) {System.out.println ("This is right!"); Count1++; }                             Else{System.out.println ("This is wroing!" + "The correct answer is:" +string.format ("%.2f", A/b)); Count2++; }}} System.out.println ("The question is:" +count1+ "" + "Wrong:" +count2+ "" + "to be divided into:" +5*count1); }                Else if(2 = =op) {}               Else if(3 = =op) {                   //molecule                   intq,p; //Denominator                   inty,w; System.out.println ("(5 points/way) Please enter the number of questions:"); intn=Sc.nextint (); System.out.print ("Please enter the range of arithmetic (from small to Large):"); intmin=Sc.nextint (); intmax=Sc.nextint (); if(min>max) {System.out.print ("Input Error");  Break; } Random R=NewRandom ();  for(i=0;i<n;i++) {Q=r.nextint (max)% (max-min+1) +min; P=r.nextint (max)% (max-min+1) +min; Y=r.nextint (max)% (max-min+1) +min; W=r.nextint (max)% (max-min+1) +min; intL= R.nextint (s.length);//random number, less than the length of the array, 0~3                         if((q<y && y!=0) | | (P<w && w!=0) {System.out.println (q+ "/" +y+s[l]+p+ "/" +w);//Print Random charactersSystem.out.print ("="); DoubleA=sc.nextdouble (); }                     }               }               Else{System.out.println ("Input error, please re-enter;"); }              }                    }}

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At first, see the topic began to do, no detailed planning, consider their own ideas, think clearly need to define a few classes to achieve the function, the results of all my code is in the main function inside, resulting in my later I wrote the more chaotic, wrong, so seriously formed a bad habit. So I decided to slow down my steps, not blindly pursue to run the results. I want to learn how to use the class to write my program, look at the teacher guidance, thank you!

Arithmetic Upgrade 2