i have a text file i want to add its data to priority queue and then print out 5 items with max value each line first has a name then a date then a value i want to print 5 max values with name and date

Queue<String> queue = new PriorityQueue<String>();
String file = "file";
String line;
int order = 1;
try{
    FileReader fr = new FileReader(file);
    BufferedReader br = new BufferedReader(fr);
    while ((line = br.readLine()) != null)   {
        queue.offer(line);
    }
    br.close();
} catch (IOException e){
    System.out.println("File not found");
}
while (!queue.isEmpty()){
    System.out.println(order   ".Number: "   queue.poll());
    order  ;
}

data.txt :

tloxJcdiMqMWyDW 1976-11-24 3747
KWuHczAFXRGCeTZ 2015-12-5 1740
SyAckDyYyZhrsEK 1920-8-3 3164
pjKEnTTfcdoJwMy 2016-12-28 1941
ZsvJcYbmOFmdXfG 1923-10-10 8314
qkqDyFhObQVpByH 1934-7-21 4907
IRUMpmTSmJDVIJU 2012-12-26 376
nOCCDAmTilqnukW 1968-5-3 5811
uecbYlaCeaTSAsr 1937-4-1 9305
AMdPXptNGayPPAM 1949-2-25 1130
afTQNxogdxpQRpF 1912-11-18 5637
hBUJpjBJgyShNqk 2011-12-9 4075
dMGDWfIrPctuwBs 2005-3-15 8567
UBELfqonZOmmEGf 1954-7-29 7875
EuMbAKoKwYYERxy 1902-3-4 8291
OXvvwLXJjsXrfVI 1927-4-29 4693
amHPTQXCqHkYtXW 1991-8-24 8778
gfAcsQpChfukGlK 1971-7-14 4204
WHguJUYeLBYoton 1987-11-24 9664
ZvMoXwJqLhBlWiG 2006-6-7 7893

i have tried some other ways to save data to PQ and still didnt get any result

CodePudding user response：

Once you have your data class (let's call it Order) then you can do:

    Queue<Order> orders = Files.lines(Path.of(args[0]))
        .map(line -> line.split("  "))
        .map(Order::new)
        .collect(Collectors.toCollection(PriorityQueue::new));

If you've made your class Comparable then all should be well.

CodePudding user response：

Assuming you want compare by "value" i.e last value in input record e.g. 3747 from given input record "tloxJcdiMqMWyDW 1976-11-24 3747".

Queue<MyData> queue = new PriorityQueue<MyData>(new Comparator<MyData>()
        {
            @Override
            public int compare(MyData o1, MyData o2)
            {
                return o2.getValue() - o1.getValue();
            }
        });
        String file = "file";
        String line;
        int order = 1;
        DateTimeFormatter formatter = new DateTimeFormatterBuilder()
                .appendOptional(DateTimeFormatter.ofPattern("yyyy-M-d"))
                .toFormatter();

        List<String> lines = new ArrayList<>();
        try{
            FileReader fr = new FileReader(file);
            BufferedReader br = new BufferedReader(fr);
            while ((line = br.readLine()) != null)   {
                lines.add(line);
                String data[] = line.split("\\s");
                MyData myData = new MyData(data[0],LocalDate.parse(data[1],formatter),Integer.parseInt(data[2]));
                queue.offer(myData);
            }
            br.close();
        } catch (IOException e){
            System.out.println("File not found");
        }

        while (!queue.isEmpty()){
            System.out.println(order   ".Number: "   queue.poll().getValue());
            order  ;
        }

I created a class with three fields from input file assuming these are separated by space

import java.time.LocalDate;
import java.util.Objects;

public class MyData
{
    private String name;
    private LocalDate date;
    private int value;

    public MyData(String name, LocalDate date, int value)
    {
        this.name = name;
        this.date = date;
        this.value = value;
    }

    public int getValue()
    {
        return value;
    }

    @Override
    public boolean equals(Object o)
    {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        MyData myData = (MyData) o;
        return value == myData.value && Objects.equals(name, myData.name) && Objects.equals(date, myData.date);
    }

    @Override
    public int hashCode()
    {
        return Objects.hash(name, date, value);
    }
}

If you want only first 5 values then you can add if condition in below while loop and break once order reaches 5.

while (!queue.isEmpty()){
            System.out.println(order   ".Number: "   queue.poll().getValue());
            order  ;
        }