Can't make String equal method and Converting Strings to Numbers work together.

Question

It is a Java beginner question. The program is not complicated, it just asks the user input grade and then finish it when the user input "y" , and then calculate max, min,average, and total.

My trouble is that I can't stop the loop when I type y. Thank you so much, if anyone can help me out. I have tried many approaches to figure that.

    do
       { 
        System.out.println("please go on");
        input = keyboard.next();                    
        grade = Integer.parseInt(input);
        InputTimes++;
        if (grade>Maxgrade)
        {   
            Maxgrade = grade;       
         }

        if(Mingrade>grade)
        {
            Mingrade= grade;            
        }

        if (input.equals("y"))
        {   
            GameOver = true;
            System.out.println("yyyyyyy");
            break;
        }   
        else 
        {
            GameOver = false;
            System.out.println("nnnnnn");   
        }   
        totalgradeNoF = grade+totalgradeNoF;

    }while(GameOver==false);

maybe http://stackoverflow.com/questions/13102045/scanner-is-skipping-nextline-after-using-next-nextint-or-other-nextfoo — Scary Wombat, Jun 30 '17 at 07:24
if you enter `y` then it will throw exception when executing `Integer.parseInt()` — Kaushal28, Jun 30 '17 at 07:25
while(!input.contains("y")); give condition like this way in your while loop — Pravin Fofariya, Jun 30 '17 at 07:47

score 0 · Accepted Answer · edited Jun 30 '17 at 07:40

Scanner keyboard = new Scanner(System.in);
int Maxgrade = 0, Mingrade = 0, InputTimes = 0, grade = 0, totalgradeNoF = 0;
boolean GameOver = false;
String input = "";
do {
    System.out.println("Please go on : ('y' to stop)");
    input = keyboard.nextLine();
    if (input.equals("y")) {
        GameOver = true;
    } else {
        grade = Integer.parseInt(input);
        InputTimes++;

        if (grade > Maxgrade) {
             Maxgrade = grade;
        }
        if (Mingrade > grade) {
             Mingrade = grade;
        }

        totalgradeNoF = grade + totalgradeNoF;
   }
} while (!GameOver);

Some things to change :

You need to check the "y" BEFORE and if it is not a "y" so you can cast to int
You don"t need to use breakso
You may use !GameoOver instead of GameOver==false
Don't need to set Gameover=false at each iteration, just at the initialisation

appreciate it, in the beginning, I thought java can automatically ignore my input which is not number. Thank you so much ! — Redick, Jul 02 '17 at 20:49

score 0 · Answer 2 · answered Jun 30 '17 at 07:33

0

When you enter 'y' NumberFormatException is coming, so you need to handle this exception and then you can exit from the loop after typing 'y'.

answered Jun 30 '17 at 07:33

Mohit Tyagi

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score 0 · Answer 3 · answered Jun 30 '17 at 07:35

Use for Scanner methods nextInt() and nextLine() for reading input.

EX:-

Scanner scan = new Scanner(System.in);

then we can use scan.nextInt() for get int

and we can use scan.nextLine() for get Strings

https://www.tutorialspoint.com/java/util/scanner_next.htm
this link may be help for you.

sorry for my english.

Can't make String equal method and Converting Strings to Numbers work together.

3 Answers3