BAEL-1351 RegEx for matching Date Pattern in Java (#3217)

* kugaudo/igor@kugaudo.com

* BAEL-1351 RegEx for matching Date Pattern in Java

* BAEL-1351 RegEx for matching Date Pattern in Java

* BAEL-1351 RegEx for matching Date Pattern in Java

* Fixed names of test methods

* Refactored class names, split unit tests by classes

* Reordered test cases in Gregorian date matcher unit test, formatted code

* Added override annotation

* Renamed mather main method for better semantics

* Fixed names of test methods

* Split Gregorian date matcher to separate branches

* Fixed test cases according to the article

* Revert "Merge branch 'master' into datepattern"

This reverts commit 0d57456140bc9e1f36d32b3e707acd2729b2c60f, reversing
changes made to c768132dcd24d4312567298f34c67cb31dcde9f8.

core-java/src/main/java/com/baeldung/regexp/datepattern/DateMatcher.java

@@ -0,0 +1,7 @@
+package com.baeldung.regexp.datepattern;
+
+public interface DateMatcher {
+
+    boolean matches(String date);
+
+}

core-java/src/main/java/com/baeldung/regexp/datepattern/FormattedDateMatcher.java

@@ -0,0 +1,14 @@
+package com.baeldung.regexp.datepattern;
+
+import java.util.regex.Pattern;
+
+class FormattedDateMatcher implements DateMatcher {
+
+    private static final Pattern DATE_PATTERN = Pattern.compile(
+            "^\\d{4}-\\d{2}-\\d{2}$");
+
+    @Override
+    public boolean matches(String date) {
+        return DATE_PATTERN.matcher(date).matches();
+    }
+}

core-java/src/main/java/com/baeldung/regexp/datepattern/RangedDateMatcher.java

@@ -0,0 +1,14 @@
+package com.baeldung.regexp.datepattern;
+
+import java.util.regex.Pattern;
+
+class RangedDateMatcher implements DateMatcher {
+
+    private static final Pattern DATE_PATTERN = Pattern.compile(
+            "^((19|2[0-9])[0-9]{2})-(0[1-9]|1[012])-(0[1-9]|[12][0-9]|3[01])$");
+
+    @Override
+    public boolean matches(String date) {
+        return DATE_PATTERN.matcher(date).matches();
+    }
+}

core-java/src/main/java/com/baeldung/regexp/datepattern/gregorian/February29thMatcher.java

@@ -0,0 +1,16 @@
+package com.baeldung.regexp.datepattern.gregorian;
+
+import com.baeldung.regexp.datepattern.DateMatcher;
+
+import java.util.regex.Pattern;
+
+public class February29thMatcher implements DateMatcher {
+
+    private static final Pattern DATE_PATTERN = Pattern.compile(
+            "^((2000|2400|2800|(19|2[0-9](0[48]|[2468][048]|[13579][26])))-02-29)$");
+
+    @Override
+    public boolean matches(String date) {
+        return DATE_PATTERN.matcher(date).matches();
+    }
+}

core-java/src/main/java/com/baeldung/regexp/datepattern/gregorian/FebruaryGeneralMatcher.java

@@ -0,0 +1,16 @@
+package com.baeldung.regexp.datepattern.gregorian;
+
+import com.baeldung.regexp.datepattern.DateMatcher;
+
+import java.util.regex.Pattern;
+
+public class FebruaryGeneralMatcher implements DateMatcher {
+
+    private static final Pattern DATE_PATTERN = Pattern.compile(
+            "^(((19|2[0-9])[0-9]{2})-02-(0[1-9]|1[0-9]|2[0-8]))$");
+
+    @Override
+    public boolean matches(String date) {
+        return DATE_PATTERN.matcher(date).matches();
+    }
+}

core-java/src/main/java/com/baeldung/regexp/datepattern/gregorian/GregorianDateMatcher.java

@@ -0,0 +1,19 @@
+package com.baeldung.regexp.datepattern.gregorian;
+
+import com.baeldung.regexp.datepattern.DateMatcher;
+
+import java.util.regex.Pattern;
+
+class GregorianDateMatcher implements DateMatcher {
+
+    private static final Pattern DATE_PATTERN = Pattern.compile(
+            "^((2000|2400|2800|(19|2[0-9](0[48]|[2468][048]|[13579][26])))-02-29)$" 
+            + "|^(((19|2[0-9])[0-9]{2})-02-(0[1-9]|1[0-9]|2[0-8]))$"
+            + "|^(((19|2[0-9])[0-9]{2})-(0[13578]|10|12)-(0[1-9]|[12][0-9]|3[01]))$" 
+            + "|^(((19|2[0-9])[0-9]{2})-(0[469]|11)-(0[1-9]|[12][0-9]|30))$");
+
+    @Override
+    public boolean matches(String date) {
+        return DATE_PATTERN.matcher(date).matches();
+    }
+}

core-java/src/main/java/com/baeldung/regexp/datepattern/gregorian/MonthsOf30DaysMatcher.java

@@ -0,0 +1,17 @@
+package com.baeldung.regexp.datepattern.gregorian;
+
+import com.baeldung.regexp.datepattern.DateMatcher;
+
+import java.util.regex.Pattern;
+
+public class MonthsOf30DaysMatcher implements DateMatcher {
+
+    private static final Pattern DATE_PATTERN = Pattern.compile(
+            "^(((19|2[0-9])[0-9]{2})-(0[469]|11)-(0[1-9]|[12][0-9]|30))$");
+
+    @Override
+    public boolean matches(String date) {
+        return DATE_PATTERN.matcher(date).matches();
+    }
+
+}

core-java/src/main/java/com/baeldung/regexp/datepattern/gregorian/MonthsOf31DaysMatcher.java

@@ -0,0 +1,17 @@
+package com.baeldung.regexp.datepattern.gregorian;
+
+import com.baeldung.regexp.datepattern.DateMatcher;
+
+import java.util.regex.Pattern;
+
+public class MonthsOf31DaysMatcher implements DateMatcher {
+
+    private static final Pattern DATE_PATTERN = Pattern.compile(
+            "^(((19|2[0-9])[0-9]{2})-(0[13578]|10|12)-(0[1-9]|[12][0-9]|3[01]))$");
+
+    @Override
+    public boolean matches(String date) {
+        return DATE_PATTERN.matcher(date).matches();
+    }
+
+}

core-java/src/test/java/com/baeldung/regexp/datepattern/FormattedDateMatcherUnitTest.java

@@ -0,0 +1,24 @@
+package com.baeldung.regexp.datepattern;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+public class FormattedDateMatcherUnitTest {
+
+    private DateMatcher matcher = new FormattedDateMatcher();
+
+    @Test
+    public void whenUsingFormattedDateMatcher_thenFormatConstraintsSatisfied() {
+        Assert.assertTrue(matcher.matches("2017-12-31"));
+        Assert.assertTrue(matcher.matches("2018-01-01"));
+        Assert.assertTrue(matcher.matches("0000-00-00"));
+        Assert.assertTrue(matcher.matches("1029-99-72"));
+
+        Assert.assertFalse(matcher.matches("2018-01"));
+        Assert.assertFalse(matcher.matches("2018-01-01-01"));
+        Assert.assertFalse(matcher.matches("2018-01-XX"));
+        Assert.assertFalse(matcher.matches(" 2018-01-01"));
+        Assert.assertFalse(matcher.matches("2018-01-01 "));
+        Assert.assertFalse(matcher.matches("2018/01/01"));
+    }
+}

core-java/src/test/java/com/baeldung/regexp/datepattern/RangedDateMatcherUnitTest.java

@@ -0,0 +1,31 @@
+package com.baeldung.regexp.datepattern;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+public class RangedDateMatcherUnitTest {
+
+    private DateMatcher matcher = new RangedDateMatcher();
+
+    @Test
+    public void whenUsingRangedDateMatcher_thenFormatConstraintsSatisfied() {
+        Assert.assertFalse(matcher.matches("2018-01"));
+        Assert.assertFalse(matcher.matches("2018-01-01-01"));
+        Assert.assertFalse(matcher.matches("2018-01-XX"));
+        Assert.assertFalse(matcher.matches(" 2018-01-01"));
+        Assert.assertFalse(matcher.matches("2018-01-01 "));
+        Assert.assertFalse(matcher.matches("2018/01/01"));
+    }
+
+    @Test
+    public void whenUsingRangedDateMatcher_thenRangeConstraintsSatisfied() {
+        Assert.assertTrue(matcher.matches("1900-01-01"));
+        Assert.assertTrue(matcher.matches("2018-02-31"));
+        Assert.assertTrue(matcher.matches("2999-12-31"));
+
+        Assert.assertFalse(matcher.matches("1899-12-31"));
+        Assert.assertFalse(matcher.matches("2018-05-35"));
+        Assert.assertFalse(matcher.matches("2018-13-05"));
+        Assert.assertFalse(matcher.matches("3000-01-01"));
+    }
+}

core-java/src/test/java/com/baeldung/regexp/datepattern/gregorian/February29thMatcherUnitTest.java

@@ -0,0 +1,17 @@
+package com.baeldung.regexp.datepattern.gregorian;
+
+import com.baeldung.regexp.datepattern.DateMatcher;
+import com.baeldung.regexp.datepattern.gregorian.testhelper.GregorianDateTestHelper;
+import org.junit.Test;
+
+public class February29thMatcherUnitTest {
+
+    private DateMatcher matcher = new February29thMatcher();
+
+    private GregorianDateTestHelper testHelper = new GregorianDateTestHelper(matcher);
+
+    @Test
+    public void whenYearIsLeap_thenYearHasFebruary29th() {
+        testHelper.assertFebruary29th();
+    }
+}

core-java/src/test/java/com/baeldung/regexp/datepattern/gregorian/FebruaryGeneralMatcherUnitTest.java

@@ -0,0 +1,17 @@
+package com.baeldung.regexp.datepattern.gregorian;
+
+import com.baeldung.regexp.datepattern.DateMatcher;
+import com.baeldung.regexp.datepattern.gregorian.testhelper.GregorianDateTestHelper;
+import org.junit.Test;
+
+public class FebruaryGeneralMatcherUnitTest {
+
+    private DateMatcher matcher = new FebruaryGeneralMatcher();
+
+    private GregorianDateTestHelper testHelper = new GregorianDateTestHelper(matcher);
+
+    @Test
+    public void whenMonthIsFebruary_thenMonthContainsUpTo28Days() {
+        testHelper.assertFebruaryGeneralDates();
+    }
+}

core-java/src/test/java/com/baeldung/regexp/datepattern/gregorian/GregorianDateMatcherUnitTest.java

@@ -0,0 +1,42 @@
+package com.baeldung.regexp.datepattern.gregorian;
+
+import com.baeldung.regexp.datepattern.DateMatcher;
+import com.baeldung.regexp.datepattern.gregorian.testhelper.GregorianDateTestHelper;
+import org.junit.Test;
+
+public class GregorianDateMatcherUnitTest {
+
+    private DateMatcher matcher = new GregorianDateMatcher();
+
+    private GregorianDateTestHelper testHelper = new GregorianDateTestHelper(matcher);
+
+    @Test
+    public void whenUsingGregorianDateMatcher_thenFormatConstraintsSatisfied() {
+        testHelper.assertFormat();
+    }
+
+    @Test
+    public void whenUsingGregorianDateMatcher_thenRangeConstraintsSatisfied() {
+        testHelper.assertRange();
+    }
+
+    @Test
+    public void whenYearIsLeap_thenFebruaryHas29Days() {
+        testHelper.assertFebruary29th();
+    }
+
+    @Test
+    public void whenMonthIsFebruary_thenMonthContainsUpTo28Days() {
+        testHelper.assertFebruaryGeneralDates();
+    }
+
+    @Test
+    public void whenMonthIsShort_thenMonthContainsUpTo30Days() {
+        testHelper.assertMonthsOf30Days();
+    }
+
+    @Test
+    public void whenMonthIsLong_thenMonthContainsUpTo31Days() {
+        testHelper.assertMonthsOf31Dates();
+    }
+}

core-java/src/test/java/com/baeldung/regexp/datepattern/gregorian/MonthsOf30DaysMatcherUnitTest.java

@@ -0,0 +1,17 @@
+package com.baeldung.regexp.datepattern.gregorian;
+
+import com.baeldung.regexp.datepattern.DateMatcher;
+import com.baeldung.regexp.datepattern.gregorian.testhelper.GregorianDateTestHelper;
+import org.junit.Test;
+
+public class MonthsOf30DaysMatcherUnitTest {
+
+    private DateMatcher matcher = new MonthsOf30DaysMatcher();
+
+    private GregorianDateTestHelper testHelper = new GregorianDateTestHelper(matcher);
+
+    @Test
+    public void whenMonthIsShort_thenMonthContainsUpTo30Days() {
+        testHelper.assertMonthsOf30Days();
+    }
+}

core-java/src/test/java/com/baeldung/regexp/datepattern/gregorian/MonthsOf31DaysMatcherUnitTest.java

@@ -0,0 +1,17 @@
+package com.baeldung.regexp.datepattern.gregorian;
+
+import com.baeldung.regexp.datepattern.DateMatcher;
+import com.baeldung.regexp.datepattern.gregorian.testhelper.GregorianDateTestHelper;
+import org.junit.Test;
+
+public class MonthsOf31DaysMatcherUnitTest {
+
+    private DateMatcher matcher = new MonthsOf31DaysMatcher();
+
+    private GregorianDateTestHelper testHelper = new GregorianDateTestHelper(matcher);
+
+    @Test
+    public void whenMonthIsLong_thenMonthContainsUpTo31Days() {
+        testHelper.assertMonthsOf31Dates();
+    }
+}

core-java/src/test/java/com/baeldung/regexp/datepattern/gregorian/testhelper/GregorianDateTestHelper.java

@@ -0,0 +1,102 @@
+package com.baeldung.regexp.datepattern.gregorian.testhelper;
+
+import com.baeldung.regexp.datepattern.DateMatcher;
+import org.junit.Assert;
+
+public class GregorianDateTestHelper {
+
+    private final DateMatcher matcher;
+
+    public GregorianDateTestHelper(DateMatcher matcher) {
+        this.matcher = matcher;
+    }
+
+    public void assertFormat() {
+        Assert.assertTrue(matcher.matches("2017-12-31"));
+        Assert.assertTrue(matcher.matches("2018-01-01"));
+
+        Assert.assertFalse(matcher.matches("2018-02"));
+        Assert.assertFalse(matcher.matches("2018-02-01-01"));
+        Assert.assertFalse(matcher.matches("2018-02-XX"));
+        Assert.assertFalse(matcher.matches(" 2018-02-01"));
+        Assert.assertFalse(matcher.matches("2018-02-01 "));
+        Assert.assertFalse(matcher.matches("2020/02/28"));
+        Assert.assertFalse(matcher.matches("2020.02.29"));
+    }
+
+    public void assertRange() {
+        Assert.assertTrue(matcher.matches("1900-01-01"));
+        Assert.assertTrue(matcher.matches("2205-05-25"));
+        Assert.assertTrue(matcher.matches("2999-12-31"));
+
+        Assert.assertFalse(matcher.matches("1899-12-31"));
+        Assert.assertFalse(matcher.matches("2018-05-35"));
+        Assert.assertFalse(matcher.matches("2018-13-05"));
+        Assert.assertFalse(matcher.matches("3000-01-01"));
+        Assert.assertFalse(matcher.matches("3200-02-29"));
+    }
+
+    public void assertFebruary29th() {
+        Assert.assertTrue(matcher.matches("2000-02-29"));
+        Assert.assertTrue(matcher.matches("2400-02-29"));
+        Assert.assertTrue(matcher.matches("2800-02-29"));
+        Assert.assertTrue(matcher.matches("2020-02-29"));
+        Assert.assertTrue(matcher.matches("2024-02-29"));
+        Assert.assertTrue(matcher.matches("2028-02-29"));
+
+        Assert.assertFalse(matcher.matches("2017-02-29"));
+        Assert.assertFalse(matcher.matches("2018-02-29"));
+        Assert.assertFalse(matcher.matches("2019-02-29"));
+        Assert.assertFalse(matcher.matches("2100-02-29"));
+        Assert.assertFalse(matcher.matches("2200-02-29"));
+        Assert.assertFalse(matcher.matches("2300-02-29"));
+    }
+
+    public void assertFebruaryGeneralDates() {
+        Assert.assertTrue(matcher.matches("2018-02-01"));
+        Assert.assertTrue(matcher.matches("2019-02-13"));
+        Assert.assertTrue(matcher.matches("2020-02-25"));
+
+        Assert.assertFalse(matcher.matches("2000-02-30"));
+        Assert.assertFalse(matcher.matches("2400-02-62"));
+        Assert.assertFalse(matcher.matches("2420-02-94"));
+    }
+
+    public void assertMonthsOf30Days() {
+        Assert.assertTrue(matcher.matches("2018-04-30"));
+        Assert.assertTrue(matcher.matches("2019-06-30"));
+        Assert.assertTrue(matcher.matches("2020-09-30"));
+        Assert.assertTrue(matcher.matches("2021-11-30"));
+
+        Assert.assertTrue(matcher.matches("2022-04-02"));
+        Assert.assertTrue(matcher.matches("2023-06-14"));
+        Assert.assertTrue(matcher.matches("2024-09-26"));
+
+        Assert.assertFalse(matcher.matches("2018-04-31"));
+        Assert.assertFalse(matcher.matches("2019-06-31"));
+        Assert.assertFalse(matcher.matches("2020-09-31"));
+        Assert.assertFalse(matcher.matches("2021-11-31"));
+
+        Assert.assertFalse(matcher.matches("2022-04-32"));
+        Assert.assertFalse(matcher.matches("2023-06-64"));
+        Assert.assertFalse(matcher.matches("2024-09-96"));
+    }
+
+    public void assertMonthsOf31Dates() {
+        Assert.assertTrue(matcher.matches("2018-01-31"));
+        Assert.assertTrue(matcher.matches("2019-03-31"));
+        Assert.assertTrue(matcher.matches("2020-05-31"));
+        Assert.assertTrue(matcher.matches("2021-07-31"));
+        Assert.assertTrue(matcher.matches("2022-08-31"));
+        Assert.assertTrue(matcher.matches("2023-10-31"));
+        Assert.assertTrue(matcher.matches("2024-12-31"));
+
+        Assert.assertTrue(matcher.matches("2025-01-03"));
+        Assert.assertTrue(matcher.matches("2026-03-15"));
+        Assert.assertTrue(matcher.matches("2027-05-27"));
+
+        Assert.assertFalse(matcher.matches("2018-01-32"));
+        Assert.assertFalse(matcher.matches("2019-03-64"));
+        Assert.assertFalse(matcher.matches("2020-05-96"));
+    }
+}