How can I use user input dates to filter out objects in an array list?-CodePudding

I have a TableView in JavaFX showing many objects' attributes, representing orders.

Screenshot of sample TableView Output Window

To do so, I have an ArrayList called items, which is filled with objects from an Item class. I've declared many objects like this:

ArrayList items = new ArrayList();
items.add(new Item("01/01/2021", 20, 10, 10, 1));
items.add(new Item("01/21/2021", 15, 5, 10, 2));
items.add(new Item("02/11/2021", 12, 6, 6, 1));
items.add(new Item("03/29/2021", 35, 5, 30, 7));
items.add(new Item("04/14/2021", 16, 16, 0, 0));
items.add(new Item("04/21/2021", 20, 10, 10, 1)); // etc

I wanted to know if there was a way to utilize 2 user-inputted dates (MM/dd/yyyy) to display on the TableView ONLY objects with date attributes in between the range to match the objects. I know I must remove certain objects to omit them from the TableView entirely but am unsure how.

For example, if we have the user input dates "01/01/2021" and "04/01/2021", the tableview will showcase only the first 4 items shown in the sample code.

My user input logic is already completed, but I would appreciate insight on how to edit the ArrayList itself when utilizing two dates so the TableView outputs only the correct orders.

CodePudding user response：

Firstly, define your custom class to take a LocalDate object rather than a string.

record Item ( LocalDate when , int code ) {}

Usage.

List < Item > items = 
    List.of( 
        new Item( LocalDate.of( 2022 , Month.JANUARY ,  23 ) , 10 ) ,
        new Item( LocalDate.of( 2022 , Month.FEBRUARY ,  24 ) , 11 ) ,
        new Item( LocalDate.of( 2022 , 3 ,  25 ) , 12 )
    )
;

Define your date range.

LocalDate start = LocalDate.of( 2022 , 2 , 1 ) ;
LocalDate end = start.plusMonths( 1 ) ;

Loop your list, examining each for a match.

List< Item > hits = new ArrayList <> () ;
for( Item item : items ) {
    if( ( ! item.when.isBefore( start ) ) & item.when.isBefore( end ) ) {
        hits.add( item ) ;
    }
}

Or use streams and lambdas.

List< Item > hits = items.stream().filter( item -> ( ! item.when.isBefore( start ) ) & item.when.isBefore( end ) ).toList() ;

If you are doing much of this code, I suggest adding the ThreeTen-Extra library to your project to make use of the class LocalDateRange.

CodePudding user response：

you can use the SimpleDateFormat class in the java library and take in date from the user in a particular format

try running this code of mine to have a better understanding of the class.

it takes in date in dd/mm/yyyy format and displays it in yyyy mm dd format

public class DateTime {

static void Condate(String inputDate) {
    try {
        
        SimpleDateFormat sfd=new SimpleDateFormat("dd/mm/yyyy");
        //String t=sfd.format();
        Date date=sfd.parse(inputDate);
        SimpleDateFormat outputsfd=new SimpleDateFormat("yyyy mm dd");
        String outputdate=outputsfd.format(date);
        System.out.println("after changing the date to yyyy/mm/dd : " outputdate);
        
    }catch(java.text.ParseException e){
        System.out.println("error occured");
    }
}   

public static void main(String[] args) {
    Scanner r=new Scanner(System.in);
    System.out.println("enter date is dd/mm/yyyy : ");
    String d=r.nextLine();
    Condate(d); 
    r.close();
}