Java – For loop isn't properly executing through an array

Question

I have two arrays, one is a String array full of marathon runners and the next is an Integer array full of the marathon runners' respective times. I'm trying to output the fastest runner + his/her time as well as the second fastest runner + his/her time. So far, I've been able to output the fastest runner and his time, but when I try to output the second fastest runner + her time, the loop outputs two runners' times instead of one. I've attached the code for reference:

Also, any comments in terms of simplifying/improving the code is also welcome.

public class APCS {
  public static void main(String[] arguments) {

    String[] names = {
        "Elena", "Thomas", "Hamilton", "Suzie", "Phil", "Matt", "Alex",
        "Emma", "John", "James", "Jane", "Emily", "Daniel", "Neda",
        "Aaron", "Kate"
    };

    int[] times = {
        341, 273, 278, 329, 445, 402, 388, 275, 243, 334, 412, 393, 299,
        343, 317, 265
    };

    int timeIndex = 0;
    int secondTimeIndex = 0;
    for (int i = 0; i < times.length; i++) {
        if (times[i] > times[timeIndex]) {
            timeIndex = i;
            System.out.println(names[timeIndex] + " " + times[timeIndex]);
        }

        if (times[i] > times[secondTimeIndex]) {
            if (times[i] == times[timeIndex]) {
                continue;
            }
            secondTimeIndex = i;
            System.out.println(names[secondTimeIndex] + " " + times[secondTimeIndex]);
        }
    }

  }
}

This is my output:

Phil 445
Matt 402
Jane 412

I would consider using a Map - that might simplify your code. SortedMap might be very useful for you. — Erveron
– Erveron, Commented Aug 10, 2015 at 21:03
@James: or a class Runner implements Comparable<Runner> type class that holds String name and int time fields, and then sort the array or List. Or better still, use a Comparator<Runner>. — Hovercraft Full Of Eels
– Hovercraft Full Of Eels, Commented Aug 10, 2015 at 21:04
CS101: Since you're outputting a fixed amount of data (exactly 2, not data-per-person), the output statements need to be outside the loop. — Lee Daniel Crocker
– Lee Daniel Crocker, Commented Aug 10, 2015 at 21:10
You are printing out the fast running found so far, you should be be printing out the fastest running over all, after the loop has run. — Peter Lawrey
– Peter Lawrey, Commented Aug 10, 2015 at 21:13

Hovercraft Full Of Eels · Accepted Answer · 2015-08-10 21:01:37Z

4

Your System.out.println is in the wrong place and now is reporting changes in the desired indices, not the final results. The printlns should be called after the for loop has completed.

for (int i = 0; i < times.length; i++) {
    if (times[i] > times[timeIndex]) {
        timeIndex = i;
        //System.out.println(names[timeIndex] + " " + times[timeIndex]);
    }

    if (times[i] > times[secondTimeIndex]) {
        if (times[i] == times[timeIndex]) {
            continue;
        }
        secondTimeIndex = i;
        //System.out.println(names[secondTimeIndex] + " " + times[secondTimeIndex]);
    }
}
System.out.println("Fastest: " + names[timeIndex] + " " + times[timeIndex]);
System.out.println("Second: " + names[secondTimeIndex] + " " + times[secondTimeIndex]);

answered Aug 10, 2015 at 21:01

Hovercraft Full Of Eels

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1 Comment

Trevor Freeman Over a year ago

This code looks like it has 2 bugs to me that were part of the original code. First, the reqs are looking for fastest time (according to the question), which should be the lowest time, not the greatest, right? Second, if the second fastest time appears before the fastest time in the list, then it will be skipped over and never have its index registered into secondTimeIndex.

questioner and answerer · Accepted Answer · 2015-08-10 21:15:23Z

1

Because you're writing this in Java, you shouldn't be using parallel arrays. Java is specifically designed to be object oriented, so I suggest using objects to represent the marathon runners.

For example, you can declare a Runner class as such:

public class Runner implements Comparable<Runner> {
    private String name = null;
    private int time = 0;

    public Runner(String name, int time) {
        this.name = name;
        this.time = time;
    }

    public String toString() {
        return name + " " + time;
    }

    public int compareTo(Runner r) {
        return (r.time - time);
    }
}

compareTo is implemented so you can sort the list of runners.

Then you create the list of runners and sort them with the Arrays class.

Runner[] runners = new Runner[16];
runners[0] = new Runner("Elena", 341); //and so on, creating all runners

Arrays.sort(runners); //runners will now be sorted according to times
System.out.println(runners[i].toString()); //first place
System.out.println(runners[1].toString()); //second place

answered Aug 10, 2015 at 21:15

questioner and answerer

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2 Comments

beresfordt Over a year ago

System.out.println(runners[i].toString()) needs fixing

questioner and answerer Over a year ago

What do you mean by "needs fixing"?

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