[BAEL-4136] What is this: [Ljava.lang.Object;?

Code article

core-java-modules/core-java-io-conversions-2/src/test/java/com/baeldung/arraystostring/JavaArraysToStringUnitTest.java

@@ -0,0 +1,36 @@
+package com.baeldung.arraystostring;
+
+import org.junit.Test;
+
+import java.util.Arrays;
+import java.util.List;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+
+public class JavaArraysToStringUnitTest {
+
+        @Test public void givenInstanceOfArray_whenTryingToConvertToString_thenNameOfClassIsShown() {
+                Object[] arrayOfObjects = { "John", 2, true };
+                assertTrue(arrayOfObjects.toString().startsWith("[Ljava.lang.Object;"));
+        }
+
+        @Test public void givenInstanceOfArray_useArraysToStringToConvert_thenValueOfObjectsAreShown() {
+                Object[] arrayOfObjects = { "John", 2, true };
+                assertEquals(Arrays.toString(arrayOfObjects), "[John, 2, true]");
+        }
+
+        @Test public void givenInstanceOfDeepArray_userArraysDeepToStringToConvert_thenValueOfInnerObjectsAreShown() {
+                Object[] innerArray = { "We", "Are", "Inside" };
+                Object[] arrayOfObjects = { "John", 2, innerArray };
+                assertEquals(Arrays.deepToString(arrayOfObjects), "[John, 2, [We, Are, Inside]]");
+        }
+
+        @Test public void givenInstanceOfDeepArray_useStreamsToConvert_thenValueOfObjectsAreShown() {
+                Object[] arrayOfObjects = { "John", 2, true };
+                List<String> listOfString = Stream.of(arrayOfObjects).map(Object::toString).collect(Collectors.toList());
+                assertEquals(listOfString.toString(), "[John, 2, true]");
+        }
+}