按开始和结束时间过滤带有日期的ArrayList [英] Filter an ArrayList with Dates by start and end time

问题描述

我正在实现一个简单的ListView，其中数据源是一个ArrayList，其中包含Name，Start和End日期。在iOS中，我会使用一个简单的NSPredicate来过滤数组，但在Android和Java中，我对我应该使用的内容感到困惑。欢迎任何建议。

I am implementing a simple ListView where the data source is an ArrayList with that contains Name, Start and End dates. In iOS I would use a simple NSPredicate to filter the array but here in Android and Java I am confused of what I should use. Any suggestions are welcomed.

推荐答案

您可以使用Date.before和Date.after方法。这些允许您过滤日期列表（对于特定范围（例如1月）的日期）：

You can use the Date.before, and Date.after methods. These allow you to filter a list of dates (for ones in a specific range (for example January)):

a。使用带有开始日期和结束日期的Java 8过滤器。

a. Use a Java 8 filter, with a start, and end date.

b。使用Java循环/迭代器来检查开始和结束日期。

b. Use a Java loop / iterator, to check start and end date.

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Date;
import java.util.stream.Collectors;

public class FilterStartAndEndDate {

    private SimpleDateFormat sdf = new SimpleDateFormat("dd/MM/yyyy");
    private Collection<Date> dateList = null;
    private Date start = null;
    private Date end = null;

    private FilterStartAndEndDate() throws ParseException {
        dateList = new ArrayList<Date>() {{
            add(sdf.parse("01/01/2016"));
            add(sdf.parse("02/01/2016"));
            add(sdf.parse("03/02/2016"));
            add(sdf.parse("04/01/2016"));
            add(sdf.parse("05/01/2016"));
        }};

        start = sdf.parse("31/12/2015");
        end = sdf.parse("01/02/2016");
    }

    /**
     * Filter dates with Lambda
     *
     * @throws ParseException
     */
    private void getDatesBetweenStartAndFinishWithFilter() throws ParseException {
        dateList.stream()
                .filter(dates -> dates.after(start) && dates.before(end))
                .collect(Collectors.toList())
                .forEach(januaryDate->System.out.println(januaryDate));
    }

    /**
     * Filter dates with Iterator
     *
     * @throws ParseException
     */
    private void getDatesBetweenStartAndFinish() throws ParseException {
        Collection<Date> datesInJanuaryList = new ArrayList<>();

        for (Date eachDate : dateList) {
            if (eachDate.after(start) && eachDate.before(end)) {
                datesInJanuaryList.add(eachDate);
            }
        }

        for (Date eachDate : datesInJanuaryList) {
            System.out.println(eachDate);
        }
    }


    public static void main(String[] args) throws Exception {
        FilterStartAndEndDate datesInJanuary = new FilterStartAndEndDate();
        datesInJanuary.getDatesBetweenStartAndFinish();
        datesInJanuary.getDatesBetweenStartAndFinishWithFilter();
    }
}

示例代码过滤日期为1月，使用Lambda filter和Java迭代器。两者都使用方法之前和之后的日期。

The example code filter dates in January, using a Lambda filter, and a Java iterator. Both use the Date before and after methods.

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