Java Community | Help. Code. Learn.•3y ago

Java Stream Issue

I have a problem about writing a java stream by filtering multiple conditions , groupby multiple condition (if possible) and calculating the sum value I store the values as Map<String(pId),List<Person>> Here is my Person class shown below

    public class Person{
    
        private String id;
        private Statement event; // STATUS1,STATUS2
        private LocalDate eventDate;
        private Object value;
    }

    public class Person{
    
        private String id;
        private Statement event; // STATUS1,STATUS2
        private LocalDate eventDate;
        private Object value;
    }

Here is the list

    ID,Info,Date,Value (All values are stored in Person object defined in the List)
    
    per1, STATUS1,  10-01-2022, 1
    per2, STATUS2, 10-01-2022, 2
    per3, STATUS3, 10-01-2022, 3 
    per1 STATUS1, 10-02-2022, 1
    per2, STATUS1, 10-03-2022, 1
    per3, STATUS2, 10-03-2022, 2
    ...
    ...

    ID,Info,Date,Value (All values are stored in Person object defined in the List)
    
    per1, STATUS1,  10-01-2022, 1
    per2, STATUS2, 10-01-2022, 2
    per3, STATUS3, 10-01-2022, 3 
    per1 STATUS1, 10-02-2022, 1
    per2, STATUS1, 10-03-2022, 1
    per3, STATUS2, 10-03-2022, 2
    ...
    ...

What I want to do is to get this result.

    Month |  Total Sum | Person Count
    1        6          3
    2        1          1
    3        3          2

    Month |  Total Sum | Person Count
    1        6          3
    2        1          1
    3        3          2

Here is group dto shown below

    public class GroupDto {
            private int month;
    }

    public class GroupDto {
            private int month;
    }

Here is my dto shown below.

    public class DTO {
        private int month;
        private int totalSum; 
        private int totalPersons;  
    }

    public class DTO {
        private int month;
        private int totalSum; 
        private int totalPersons;  
    }

Here is the code snippet but I cannot complete it.

    List<DTO > result = persons .values().stream()
                .flatMap(List::stream)
                .filter(person -> person .getInfo() == Value.STATUS1|| person .getInfo() == Value.STATUS2 || person .getInfo() == Value.STATUS3)
                .collect(Collectors.groupingBy(
                        p -> new GroupDto(p.getEventDate().getMonthValue())  // CANNOT COMPLETE
                ))
                .entrySet().stream()
                .map(entry -> new DTO(entry.getKey().getMonth(), ....) // CANNOT COMPLETE
                .sorted(Comparator.comparing(DTO::getMonth))
                .toList();

    List<DTO > result = persons .values().stream()
                .flatMap(List::stream)
                .filter(person -> person .getInfo() == Value.STATUS1|| person .getInfo() == Value.STATUS2 || person .getInfo() == Value.STATUS3)
                .collect(Collectors.groupingBy(
                        p -> new GroupDto(p.getEventDate().getMonthValue())  // CANNOT COMPLETE
                ))
                .entrySet().stream()
                .map(entry -> new DTO(entry.getKey().getMonth(), ....) // CANNOT COMPLETE
                .sorted(Comparator.comparing(DTO::getMonth))
                .toList();

How can I do that?

10 Replies

JavaBot•3y ago

Hey, @direct_x_34! Please remember to /close this post once your question has been answered!

Unknown User•3y ago

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direct_x_34OP•3y ago

Value should be Object not int. I just tested it but it didn't work.

per1, STATUS1,  10-01-2022, 1
    per2, STATUS2, 10-01-2022, 2
    per3, STATUS3, 10-01-2022, 3
    per1, STATUS1, 10-01-2022, 1  
    per1 STATUS1, 10-02-2022, 1
    per2, STATUS1, 10-03-2022, 1
    per3, STATUS2, 10-03-2022, 2

per1, STATUS1,  10-01-2022, 1
    per2, STATUS2, 10-01-2022, 2
    per3, STATUS3, 10-01-2022, 3
    per1, STATUS1, 10-01-2022, 1  
    per1 STATUS1, 10-02-2022, 1
    per2, STATUS1, 10-03-2022, 1
    per3, STATUS2, 10-03-2022, 2

public class DTO {
        private int month;
        private BigDecimal totalSum; 
        private int totalPersons;  
    }

public class DTO {
        private int month;
        private BigDecimal totalSum; 
        private int totalPersons;  
    }

List<Dto> group = employees.values().stream()
                    .flatMap(List::stream)
                    .filter(emp -> emp.getEvent() == Value.STATUS1 || emp.getEvent() == Value.STATUS2 
                            || emp.getEvent() == Value.STATUS3 )
                    .map(emp -> new Dto(emp.getEventDate().getMonthValue(), new BigDecimal(emp.getValue().toString()), 1)) // BigDecimal.ONE = BigDecimal.valueOf(1)
                    .collect(Collectors.toList());
    
            List<Dto> result = new ArrayList<>(group.stream()
                    .collect(Collectors.toMap(
                            dto -> Arrays.asList(dto.getMonth()), Function.identity(), Dto::aggregate))
                    .values()).stream().sorted(Comparator.comparing(Dto::getMonth))
                    .collect(Collectors.toList());

    // Defined in Dto class
    public static Dto aggregate(Dtoinitial, Dto next) {
            initial.setTotalSalary(initial.getTotalSalary().add(next.getTotalSalary()));
            initial.setTotalEmployees(initial.getTotalEmployees() + next.getTotalEmployees());
            return initial;
        }

    result.forEach(System.out::println);

Here is the same result

    Dto{month=1, totalSalary=7, totalPersons=4}
    Dto{month=2, totalSalary=1, totalPersons=1}
    Dto{month=3, totalSalary=3, totalPersons=2}

Normally, total persons in month 1 is 3 but it counts 4 with respect to status.

List<Dto> group = employees.values().stream()
                    .flatMap(List::stream)
                    .filter(emp -> emp.getEvent() == Value.STATUS1 || emp.getEvent() == Value.STATUS2 
                            || emp.getEvent() == Value.STATUS3 )
                    .map(emp -> new Dto(emp.getEventDate().getMonthValue(), new BigDecimal(emp.getValue().toString()), 1)) // BigDecimal.ONE = BigDecimal.valueOf(1)
                    .collect(Collectors.toList());
    
            List<Dto> result = new ArrayList<>(group.stream()
                    .collect(Collectors.toMap(
                            dto -> Arrays.asList(dto.getMonth()), Function.identity(), Dto::aggregate))
                    .values()).stream().sorted(Comparator.comparing(Dto::getMonth))
                    .collect(Collectors.toList());

    // Defined in Dto class
    public static Dto aggregate(Dtoinitial, Dto next) {
            initial.setTotalSalary(initial.getTotalSalary().add(next.getTotalSalary()));
            initial.setTotalEmployees(initial.getTotalEmployees() + next.getTotalEmployees());
            return initial;
        }

    result.forEach(System.out::println);

Here is the same result

    Dto{month=1, totalSalary=7, totalPersons=4}
    Dto{month=2, totalSalary=1, totalPersons=1}
    Dto{month=3, totalSalary=3, totalPersons=2}

Normally, total persons in month 1 is 3 but it counts 4 with respect to status.

How can I fix it? @Spoon

Unknown User•3y ago

Message Not Public

direct_x_34OP•3y ago

I'm getting incorrect count totalPerson because I'm not taking into account person id. I'm treating each DTO in your code as representing a distinct Person which is not true How can I do that? I think the way to solve the issue.Firstly I can create an intermediate object maintaining a set of person id to accumulate the Person instances. And then turn these objects into DTO by using the size of their Sets of ids as the person count. However, I have no idea how to implement it for my issue which I mentioned before.

Unknown User•3y ago

Message Not Public

direct_x_34OP•3y ago

Here is the example list shown below.

 ID,Info,Date,Value (All values are stored in Person object defined in the List)
    
    per1, STATUS1,  10-01-2022, 1
    per2, STATUS2, 10-01-2022, 2
    per3, STATUS3, 10-01-2022, 3 
    per1, STATUS1, 10-01-2022, 1
    per1 STATUS1, 10-02-2022, 1
    per2, STATUS1, 10-03-2022, 1
    per3, STATUS2, 10-03-2022, 2
    ...
    ...

 ID,Info,Date,Value (All values are stored in Person object defined in the List)
    
    per1, STATUS1,  10-01-2022, 1
    per2, STATUS2, 10-01-2022, 2
    per3, STATUS3, 10-01-2022, 3 
    per1, STATUS1, 10-01-2022, 1
    per1 STATUS1, 10-02-2022, 1
    per2, STATUS1, 10-03-2022, 1
    per3, STATUS2, 10-03-2022, 2
    ...
    ...

What I want to get this result as you can see below.

   Month |  Total Sum | Person Count
   1             7             3
   2             1             1
   3             3             2

   Month |  Total Sum | Person Count
   1             7             3
   2             1             1
   3             3             2

I got this result as you can see. @Spoon I cannot get the right values of total persons @Andrew Hi, I think you can help me fix my issue regarding java stream. I cannot get the right values of total persons

Unknown User•3y ago

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direct_x_34OP•3y ago

@Andrew Who can I ask it?

JavaBot•3y ago

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