Mooc Java练习78，有界计数器不接受用户输入

Question

Trying to learn java with my son. I've Googled every combination of words but can't seem to find an answer. I would appreciate any help or direction.

The program is not taking in the user input for mins/hrs to initiate counter. So counter starts at 00:00:50 for input of 23:59:50. Here is my code to date:

Main Class:

import java.util.Scanner;

public class Main {

public static void main(String[] args) {
    Scanner reader = new Scanner(System.in);

    BoundedCounter seconds = new BoundedCounter(59);
    BoundedCounter minutes = new BoundedCounter(59);
    BoundedCounter hours = new BoundedCounter(23);

    System.out.print("seconds: ");
    int s = Integer.parseInt(reader.nextLine());
    System.out.print("minutes: ");
    int m = Integer.parseInt(reader.nextLine());
    System.out.print("hours: ");
    int h = Integer.parseInt(reader.nextLine());

    seconds.setValue(s);
    minutes.setValue(m);
    hours.setValue(h);


    int i = 0;
    while ( i < 121 ) {
        System.out.println( hours + ":" + minutes + ":" + seconds);   

        seconds.next();

        if(seconds.getValue()== 0){
        minutes.next();
        }
        // if minutes become zero, advance hours
        if(minutes.getValue()== 0 && seconds.getValue()== 0){
            hours.next();
        }
        i++;
    }


}
}

public class BoundedCounter {
    private int value;
    private int upperLimit;

 public BoundedCounter(int upperLimit){
     this.value = 0;
     this.upperLimit = upperLimit;
 }
 public void next(){
    if(value < upperLimit){
        value++;
    }
    else {
        this.value = 0;
    }
    }

 public String toString(){
     if(value < 10){
         return "0" + this.value;
     }
     else{
     return "" + this.value;
}
}
 public int getValue(){
     return this.value;
 }
 public void setValue(int newValue){
     if(newValue > 0 && newValue < this.upperLimit){
         this.value = newValue;
     }

 }
}

Answer 1

Two suggestions.

Replace the while, etc., with for (int i = 0; i < 121; i++). Your way works, but using for is the more common approach.

You could type your input differently, with the seconds on one line, then the minutes on the next, and then the hours on a third. Note that you are reading the values in reverse order. That should make your existing code work.

Or, look at the API. useDelimiter() takes a regular expression that sets a delimiter. In your case, ":" should work. Then, use nextInt(). Of course, this will throw an exception if you mistype the input.

Good luck!

Answer 2

Your setValue method in the BoundedCounter class is just making your values slightly off. Your setValue method should be >= and <=:

public void setValue(int newValue){
 if(newValue >= 0 && newValue <= this.upperLimit){
     this.value = newValue;
 }}