Merge pull request #12181 from thibaultfaure/article/BAEL-5383-use-delimiters

BAEL-5383 code for the use delimiters article

core-java-modules/core-java-9/src/main/java/com/baeldung/java9/delimiters/DelimiterDemo.java

@@ -0,0 +1,36 @@
+package com.baeldung.java9.delimiters;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Scanner;
+import java.util.regex.Pattern;
+
+public class DelimiterDemo {
+
+    public static List<String> scannerWithDelimiter(String input, String delimiter) {
+        try (Scanner scan = new Scanner(input)) {
+            scan.useDelimiter(delimiter);
+            List<String> result = new ArrayList<String>();
+            scan.forEachRemaining(result::add);
+            return result;
+        }
+    }
+
+    public static List<String> scannerWithDelimiterUsingPattern(String input, Pattern delimiter) {
+        try (Scanner scan = new Scanner(input)) {
+            scan.useDelimiter(delimiter);
+            List<String> result = new ArrayList<String>();
+            scan.forEachRemaining(result::add);
+            return result;
+        }
+    }
+
+    public static List<String> baseScanner(String input) {
+        try (Scanner scan = new Scanner(input)) {
+            List<String> result = new ArrayList<String>();
+            scan.forEachRemaining(result::add);
+            return result;
+        }
+    }
+
+}

core-java-modules/core-java-9/src/test/java/com/baeldung/java9/delimiters/DelimiterDemoUnitTest.java

@@ -0,0 +1,67 @@
+package com.baeldung.java9.delimiters;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import java.util.Arrays;
+import java.util.List;
+import java.util.function.BiFunction;
+import java.util.regex.Pattern;
+
+import org.junit.jupiter.api.Test;
+
+class DelimiterDemoUnitTest {
+
+    @Test
+    void givenSimpleCharacterDelimiter_whenScannerWithDelimiter_ThenInputIsCorrectlyParsed() {
+        checkOutput(DelimiterDemo::scannerWithDelimiter, "Welcome to Baeldung", "\\s", Arrays.asList("Welcome", "to", "Baeldung"));
+    }
+
+    @Test
+    void givenStringDelimiter_whenScannerWithDelimiter_ThenInputIsCorrectlyParsed() {
+        checkOutput(DelimiterDemo::scannerWithDelimiter, "HelloBaeldungHelloWorld", "Hello", Arrays.asList("Baeldung", "World"));
+    }
+
+    @Test
+    void givenVariousPossibleDelimiters_whenScannerWithDelimiter_ThenInputIsCorrectlyParsed() {
+        checkOutput(DelimiterDemo::scannerWithDelimiter, "Welcome to Baeldung.\nThank you for reading.\nThe team", "\n|\\s", Arrays.asList("Welcome", "to", "Baeldung.", "Thank", "you", "for", "reading.", "The", "team"));
+    }
+
+    @Test
+    void givenWildcardRegexDelimiter_whenScannerWithDelimiter_ThenInputIsCorrectlyParsed() {
+        checkOutput(DelimiterDemo::scannerWithDelimiter, "1aaaaaaa2aa3aaa4", "a+", Arrays.asList("1", "2", "3", "4"));
+    }
+
+    @Test
+    void givenSimpleCharacterDelimiter_whenScannerWithDelimiterUsingPattern_ThenInputIsCorrectlyParsed() {
+        checkOutput(DelimiterDemo::scannerWithDelimiterUsingPattern, "Welcome to Baeldung", Pattern.compile("\\s"), Arrays.asList("Welcome", "to", "Baeldung"));
+    }
+
+    @Test
+    void givenStringDelimiter_whenScannerWithDelimiterUsingPattern_ThenInputIsCorrectlyParsed() {
+        checkOutput(DelimiterDemo::scannerWithDelimiterUsingPattern, "HelloBaeldungHelloWorld", Pattern.compile("Hello"), Arrays.asList("Baeldung", "World"));
+    }
+
+    @Test
+    void givenVariousPossibleDelimiters_whenScannerWithDelimiterUsingPattern_ThenInputIsCorrectlyParsed() {
+        checkOutput(DelimiterDemo::scannerWithDelimiterUsingPattern, "Welcome to Baeldung.\nThank you for reading.\nThe team", Pattern.compile("\n|\\s"), Arrays.asList("Welcome", "to", "Baeldung.", "Thank", "you", "for", "reading.", "The", "team"));
+    }
+
+    @Test
+    void givenWildcardRegexDelimiters_whenScannerWithDelimiterUsingPattern_ThenInputIsCorrectlyParsed() {
+        checkOutput(DelimiterDemo::scannerWithDelimiterUsingPattern, "1aaaaaaa2aa3aaa4", Pattern.compile("a*"), Arrays.asList("1", "2", "3", "4"));
+    }
+
+    void checkOutput(BiFunction<String, String, List<String>> function, String input, String delimiter, List<String> expectedOutput) {
+        assertEquals(expectedOutput, function.apply(input, delimiter));
+    }
+
+    void checkOutput(BiFunction<String, Pattern, List<String>> function, String input, Pattern delimiter, List<String> expectedOutput) {
+        assertEquals(expectedOutput, function.apply(input, delimiter));
+    }
+
+    @Test
+    void whenBaseScanner_ThenWhitespacesAreUsedAsDelimiters() {
+        assertEquals(List.of("Welcome", "at", "Baeldung"), DelimiterDemo.baseScanner("Welcome at Baeldung"));
+    }
+
+}