Difference Between Function(String… args) and Function(String[] args) (#13473)

core-java-modules/core-java-8-2/src/main/java/com/baeldung/argsVsvarargs/StringArrayAndVarargs.java

@@ -0,0 +1,19 @@
+package com.baeldung.argsVsvarargs;
+
+public class StringArrayAndVarargs {
+    public static void capitalizeNames(String[] args) {
+        for(int i = 0; i < args.length; i++){
+           args[i] = args[i].toUpperCase();
+        }
+
+    }
+
+    public static String[] firstLetterOfWords(String... args) {
+        String[] firstLetter = new String[args.length];
+        for(int i = 0; i < args.length; i++){
+            firstLetter[i] = String.valueOf(args[i].charAt(0));
+        }
+        return firstLetter;
+    }
+
+}

core-java-modules/core-java-8-2/src/test/java/com/baeldung/argsVsvarargs/StringArrayAndVarargsUnitTest.java

@@ -0,0 +1,24 @@
+package com.baeldung.argsVsvarargs;
+
+import static com.baeldung.argsVsvarargs.StringArrayAndVarargs.capitalizeNames;
+import static com.baeldung.argsVsvarargs.StringArrayAndVarargs.firstLetterOfWords;
+import static org.junit.jupiter.api.Assertions.*;
+
+import org.junit.jupiter.api.Test;
+
+class StringArrayAndVarargsUnitTest {
+
+    @Test
+    void whenCheckingArgumentClassName_thenNameShouldBeStringArray() {
+        String[] names = {"john", "ade", "kofi", "imo"};
+        assertNotNull(names);
+        assertEquals("java.lang.String[]", names.getClass().getTypeName());
+        capitalizeNames(names);
+    }
+
+    @Test
+    void whenCheckingReturnedObjectClass_thenClassShouldBeStringArray() {
+        assertEquals(String[].class, firstLetterOfWords("football", "basketball", "volleyball").getClass());
+        assertEquals(3, firstLetterOfWords("football", "basketball", "volleyball").length);
+    }
+}