[BAEL-6353_After-regex-match] Getting the Text That Follows After the Regex Match in Java (#13839)

core-java-modules/core-java-regex-2/src/test/java/com/baeldung/regex/aftermatch/GetTextAfterTheRegexMatchUnitTest.java

@@ -0,0 +1,83 @@
+package com.baeldung.regex.aftermatch;
+
+import org.junit.jupiter.api.Test;
+
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+public class GetTextAfterTheRegexMatchUnitTest {
+    private static final String INPUT1 = "Some text, targetValue=Regex is cool";
+    private static final String INPUT2 = "Some text. targetValue=Java is cool. some other text";
+
+    @Test
+    void whenUsingSplit_thenGetExpectedString() {
+        String result1 = INPUT1.split("targetValue=")[1];
+        assertEquals("Regex is cool", result1);
+
+        String afterFirstSplit = INPUT2.split("targetValue=")[1];
+        assertEquals("Java is cool. some other text", afterFirstSplit);
+        String result2 = afterFirstSplit.split("[.]")[0];
+        assertEquals("Java is cool", result2);
+
+        // if use the dot as the regex for splitting, the result array is empty
+        String[] splitByDot = INPUT2.split("targetValue=")[1].split(".");
+        assertEquals(0, splitByDot.length);
+    }
+
+    @Test
+    void whenUsingReplaceAll_thenGetExpectedString() {
+        String result1 = INPUT1.replaceAll(".*targetValue=", "");
+        assertEquals("Regex is cool", result1);
+
+        String afterFirstReplace = INPUT2.replaceAll(".*targetValue=", "");
+        assertEquals("Java is cool. some other text", afterFirstReplace);
+        String result2 = afterFirstReplace.replaceAll("[.].*", "");
+        assertEquals("Java is cool", result2);
+
+    }
+
+    @Test
+    void whenUsingRegexGrouping_thenGetExpectedString() {
+        Pattern p1 = Pattern.compile("targetValue=(.*)");
+        Matcher m1 = p1.matcher(INPUT1);
+        assertTrue(m1.find());
+        String result1 = m1.group(1);
+        assertEquals("Regex is cool", result1);
+
+        Pattern p2 = Pattern.compile("targetValue=([^.]*)");
+        Matcher m2 = p2.matcher(INPUT2);
+        assertTrue(m2.find());
+        String result2 = m2.group(1);
+        assertEquals("Java is cool", result2);
+
+        Pattern p3 = Pattern.compile("targetValue=(.*?)[.]");
+        Matcher m3 = p3.matcher(INPUT2);
+        assertTrue(m3.find());
+        String result3 = m3.group(1);
+        assertEquals("Java is cool", result3);
+    }
+
+    @Test
+    void whenUsingLookaround_thenGetExpectedString() {
+        Pattern p1 = Pattern.compile("(?<=targetValue=).*");
+        Matcher m1 = p1.matcher(INPUT1);
+        assertTrue(m1.find());
+        String result1 = m1.group();
+        assertEquals("Regex is cool", result1);
+
+        Pattern p2 = Pattern.compile("(?<=targetValue=)[^.]*");
+        Matcher m2 = p2.matcher(INPUT2);
+        assertTrue(m2.find());
+        String result2 = m2.group();
+        assertEquals("Java is cool", result2);
+
+        Pattern p3 = Pattern.compile("(?<=targetValue=).*(?=[.])");
+        Matcher m3 = p3.matcher(INPUT2);
+        assertTrue(m3.find());
+        String result3 = m3.group();
+        assertEquals("Java is cool", result3);
+    }
+}