How can I identify the lowest number in a group of strings?-CodePudding

I am trying to write a program that can identify which delivery driver has the lowest current delivery load.

The drivers name, location and current delivery load are in this format:

Wesley Smith, London, 4

Mark Hammond, London, 2

Abul Ali, London, 12

Ned Cayhill, London, 6

I am trying to write a program that can identify that Mark Hammond (in this instance) has the lowest load and then that entire string will be assigned to a new variable.

I have tried taking the last character (the current delivery load) from all the strings and comparing them all but then I lose a way of reconnecting that number back to its original driver.

Here is the code I have written so far (edited)

ArrayList<String> matchedDrivers = new ArrayList<String>();
ArrayList<Integer> deliveries = new ArrayList<String>();

matchedDrivers.add("Wesley Smith, London, 4");
matchedDrivers.add("Mark Hammond, London, 2");
matchedDrivers.add("Abul Ali, London, 12");
matchedDrivers.add("Ned Cayhill, London, 6");

for(int i = 0;i<matchedDrivers.size();i  ) 
{
  String mDriver = matchedDrivers.get(i);
  
  String load = mDriver.substring(mDriver.lastIndexOf(",")   1);
  int intLoad = Integer.parseInt(load)
  deliveries.add(intLoad);
}

Integer max = Collections.max(deliveries);

System.out.println(max);

Thanks in advance!

CodePudding user response：

You can iterate through the entire list and keep a variable which keeps track of the minimum that have been encountered and a variable name that keeps track of the person who has the minimum value .

To extract the minimum from the list, you can use split function of String class and then get the integer value using Integer.parseInt

class Main {
    public static void main(String args[]) {

        List<String> r = new ArrayList<>();
        r.add("Wesley Smith, London, 4");
        r.add("Mark Hammond, London, 2");
        r.add("Abul Ali, London,12");
        String driver = findLowestLoad(r);
        System.out.println(driver);
    }

    private static String findLowestLoad(List<String> r) {
        int min = Integer.MAX_VALUE;
        String name = "";
        for (int i = 0; i < r.size(); i  ) {
            int delValue = Integer.parseInt(r.get(i).split(",")[2].trim());
            if (delValue < min) {
                min = delValue;
                name = r.get(i).split(",")[0];
            }
        }
        return name;
    }

}

and the output is

Mark Hammond

CodePudding user response：

One idea¹ is to create a simple class (or record class) to hold the information:

record DeliveryDriver(
    String name,
    String location,
    int load
) {
    // empty
}

then some code to convert one input line to an instance of that class:

DeliveryDriver createDriver(String line) {
    String[] fields = line.split("\\h*,\\h*", -1);
    String name = fields[0];
    String location = fields[1];
    int load = Integer.parseInt(fields[2]);
    return new DeliveryDriver(name, location, load);
}

now you can read each line, create a driver and add it to a list (not posted here).
Once you have the List<DeliveryDriver>, you can loop over it and find the desired one:

DeliveryDriver findDriver(List<DeliveryDriver> drivers) {
    DeliveryDriver best = null;
    for (DeliveryDriver driver : drivers) {
        if (best == null || driver.load() < best.load()) {
            best = driver;
        }
    }
    return best;
}

The previous method can be written using the Java 8 Stream API in one expression:

drivers
.stream()
.sorted(Comparator.comparingInt(DeliveryDriver::load))
.findFirst()
.orElse(null);`

Once you got the driver
DeliveryDriver driver = findDriver(drivers);
you have all its information:
String name = driver.name(); or
int load = driver.load();

_{1 - code posted here is to show the basic idea, it is missing assertions, parameter tests, ... it is not meant to be complete nor error free!}