[sort-dt-str] Sort Date Strings in Java (#14188)

2023-06-10 06:00:04 +02:00 · 2023-06-10 06:00:04 +02:00 · b4b271c0e4
commit b4b271c0e4
parent c4cf873336
1 changed files with 98 additions and 0 deletions
--- a/core-java-modules/core-java-datetime-string-2/src/test/java/com/baeldung/sortdatestrings/SortDateStringsUnitTest.java
+++ b/core-java-modules/core-java-datetime-string-2/src/test/java/com/baeldung/sortdatestrings/SortDateStringsUnitTest.java
@ -0,0 +1,98 @@
+package com.baeldung.sortdatestrings;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import java.text.DateFormat;
+import java.text.ParseException;
+import java.text.SimpleDateFormat;
+import java.time.LocalDateTime;
+import java.time.format.DateTimeFormatter;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.Comparator;
+import java.util.List;
+import java.util.Map;
+import java.util.TreeMap;
+import java.util.stream.Collectors;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import com.google.common.collect.Lists;
+
+public class SortDateStringsUnitTest {
+    private List<String> dtStrings = null;
+    // @formatter:off
+    private static final List<String> EXPECTED = Lists.newArrayList(
+        "01/20/2013 06:16",
+        "01/20/2013 10:48",
+        "01/21/2013 10:41",
+        "01/21/2013 16:37",
+        "01/21/2013 17:16",
+        "01/21/2013 17:19",
+        "01/22/2013 06:19",
+        "01/22/2013 15:13"
+    );
+    // @formatter:on
+
+    @BeforeEach
+    void resetInput() {
+        // @formatter:off
+        dtStrings = Lists.newArrayList(
+          "01/21/2013 10:41",
+          "01/20/2013 10:48",
+          "01/22/2013 15:13",
+          "01/21/2013 16:37",
+          "01/21/2013 17:16",
+          "01/21/2013 17:19",
+          "01/20/2013 06:16",
+          "01/22/2013 06:19"
+        );
+        // @formatter:on
+
+    }
+
+    @Test
+    void whenUsingCustomComparator_thenGetExpectedResult() {
+        DateFormat dfm = new SimpleDateFormat("MM/dd/yyyy HH:mm");
+        Collections.sort(dtStrings, new Comparator<String>() {
+            @Override
+            public int compare(String o1, String o2) {
+                try {
+                    return dfm.parse(o1)
+                      .compareTo(dfm.parse(o2));
+                } catch (ParseException e) {
+                    throw new IllegalArgumentException(e);
+                }
+            }
+        });
+        assertEquals(EXPECTED, dtStrings);
+    }
+
+    @Test
+    void whenUsingListSort_thenGetExpectedResult() {
+        DateTimeFormatter dfm = DateTimeFormatter.ofPattern("MM/dd/yyyy HH:mm");
+        dtStrings.sort(Comparator.comparing(s -> LocalDateTime.parse(s, dfm)));
+        assertEquals(EXPECTED, dtStrings);
+    }
+
+    @Test
+    void whenUsingStreamToNewList_thenGetExpectedResult() {
+        DateTimeFormatter dfm = DateTimeFormatter.ofPattern("MM/dd/yyyy HH:mm");
+        List<String> sortedList = dtStrings.stream()
+          .map(s -> LocalDateTime.parse(s, dfm))
+          .sorted()
+          .map(dfm::format)
+          .collect(Collectors.toList());
+        assertEquals(EXPECTED, sortedList);
+    }
+
+    @Test
+    void whenUsingTreeMap_thenGetExpectedResult() {
+        DateTimeFormatter dfm = DateTimeFormatter.ofPattern("MM/dd/yyyy HH:mm");
+        Map<LocalDateTime, String> dateFormatMap = new TreeMap<>();
+        dtStrings.forEach(s -> dateFormatMap.put(LocalDateTime.parse(s, dfm), s));
+        List<String> result = new ArrayList<>(dateFormatMap.values());
+        assertEquals(EXPECTED, result);
+    }
+}