Merge pull request #16859 from sk1418/split-last-char

[split-last-char] split by the last char

Author: theangrydev

core-java-modules/core-java-string-operations-10/src/test/java/com/baeldung/splitbylastoccurrence/SplitByTheLastOccurrenceOfACharUnitTest.java

@@ -0,0 +1,78 @@
+package com.baeldung.splitbylastoccurrence;
+
+import static org.junit.jupiter.api.Assertions.assertArrayEquals;
+
+import org.junit.jupiter.api.Test;
+
+public class SplitByTheLastOccurrenceOfACharUnitTest {
+
+    private static final String INPUT1 = "a b c@e f g@x y z";
+    private static final String[] EXPECTED1 = new String[] { "a b c@e f g", "x y z" };
+
+    private static final String INPUT2 = "@a b c";
+    private static final String[] EXPECTED2 = new String[] { "", "a b c" };
+
+    private static final String INPUT3 = "a b c@";
+    private static final String[] EXPECTED3 = new String[] { "a b c", "" };
+
+    private static final String INPUT4 = "a b c";
+    private static final String[] EXPECTED4 = new String[] { "a b c" };
+
+    public String[] splitByLastOccurrence(String input, char character) {
+        int idx = input.lastIndexOf(character);
+        if (idx < 0) {
+            return new String[] { input };
+        }
+        return new String[] { input.substring(0, idx), input.substring(idx + 1) };
+    }
+
+    @Test
+    void whenUsingSplitByLastOccurrence_thenCorrect() {
+        String[] result1 = splitByLastOccurrence(INPUT1, '@');
+        assertArrayEquals(EXPECTED1, result1);
+
+        String[] result2 = splitByLastOccurrence(INPUT2, '@');
+        assertArrayEquals(EXPECTED2, result2);
+
+        String[] result3 = splitByLastOccurrence(INPUT3, '@');
+        assertArrayEquals(EXPECTED3, result3);
+
+        String[] result4 = splitByLastOccurrence(INPUT4, '@');
+        assertArrayEquals(EXPECTED4, result4);
+    }
+
+    @Test
+    void whenUsingSplitWithDefaultLimit_thenNotWorkingForInput3() {
+        String regex = "@(?=[^@]*$)";
+
+        String[] result1 = INPUT1.split(regex);
+        assertArrayEquals(EXPECTED1, result1);
+
+        String[] result2 = INPUT2.split(regex);
+        assertArrayEquals(EXPECTED2, result2);
+
+        String[] result3 = INPUT3.split(regex);
+        assertArrayEquals(new String[] { "a b c" }, result3);
+
+        String[] result4 = INPUT4.split(regex);
+        assertArrayEquals(EXPECTED4, result4);
+    }
+
+    @Test
+    void whenUsingSplitWithLimit_thenCorrect() {
+        String regex = "@(?=[^@]*$)";
+
+        String[] result1 = INPUT1.split(regex, 2);
+        assertArrayEquals(EXPECTED1, result1);
+
+        String[] result2 = INPUT2.split(regex, 2);
+        assertArrayEquals(EXPECTED2, result2);
+
+        String[] result3 = INPUT3.split(regex, 2);
+        assertArrayEquals(EXPECTED3, result3);
+
+        String[] result4 = INPUT4.split(regex, 2);
+        assertArrayEquals(EXPECTED4, result4);
+
+    }
+}