Use Java 8 Date API (JSR 310)?

[simon04]

I did some performance tests for timestamp parsing.

package org.openstreetmap.josm.tools.date;

import java.time.Instant;
import java.time.ZonedDateTime;
import java.util.Random;
import java.util.stream.IntStream;
import java.util.stream.Stream;

import org.junit.Test;

public class DateUtilsPerformanceTest {

    Stream<String> getTestData() {
        final Random random = new Random(23528390L);
        return IntStream.generate(() -> 0)
                .limit(4_000_000)
                .mapToObj(x -> String.format("%04d-%02d-%02dT%02d:%02d:%02dZ",
                        2000 + random.nextInt(20),
                        1 + random.nextInt(12),
                        1 + random.nextInt(28),
                        random.nextInt(24),
                        random.nextInt(60),
                        random.nextInt(60)
                ));
    }

    @Test
    public void testDateUtils() throws Exception {
        getTestData().forEach(DateUtils::fromString);
    }

    @Test
    public void testZonedDateTime() throws Exception {
        getTestData().forEach(ZonedDateTime::parse);
    }

    @Test
    public void testInstant() throws Exception {
        getTestData().forEach(Instant::parse);
    }
}

The results:

DateUtils.parse using Calendar.set (as is now)	14s 769ms
DateUtils.parse using ZonedDateTime.of (see patch)	13s 388ms
ZonedDateTime.parse	26s 620ms
Instant.parse	22s 222ms

So, the current DateUtil is quite performant :).

[Don-vip]

Go ahead :)

[simon04]

In 11035/josm:

see #13376 - Replace Calendar usages with Java 8 Date API

[simon04]

In 11036/josm:

see #13376 - Fix unit test

[simon04]

Left to be done/discussed: replace 257 occurrences of Date by Instant, or leave it as it is :)

[Don-vip]

Given the number of deprecated methods in Date it's almost if the class is now deprecated itself.

I'd say we can change everything that does not impact plugin API.

[simon04]

Compatibility will is a major concern since methods like AbstractPrimitive#getTimestamp, AbstractPrimitive#setTimestamp, Note#getCreatedAt, Note#getClosedAt all take/return Dates. So changing that is definitively nothing for the upcoming release. :)

[simon04]

Milestone renamed

[simon04]

In 11288/josm:

see #13376 - Use TimeUnit instead of combinations of 1000/60/60/24

[Don-vip]

Milestone renamed

[Don-vip]

New ticket for remaining point: #14176