Merge pull request #16431 from sk1418/cast-2-str-vs-str-valueOf

[cast-2-str-vs-str-valueOf] casting vs string.valueOf()

core-java-modules/core-java-string-conversions-3/src/test/java/com/baeldung/castingandstringvalueof/CastingToStringVsStringValueOfUnitTest.java

@@ -0,0 +1,50 @@
+package com.baeldung.castingandstringvalueof;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertNull;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+import java.util.List;
+
+import org.junit.jupiter.api.Test;
+
+public class CastingToStringVsStringValueOfUnitTest {
+
+    @Test
+    void whenCastingStringAndCallingValueOf_thenCorrect() {
+        Object obj = "Baeldung is awesome!";
+
+        String castResult = (String) obj;
+        assertEquals("Baeldung is awesome!", castResult);
+
+        String valueOfResult = String.valueOf(obj);
+        assertEquals("Baeldung is awesome!", valueOfResult);
+    }
+
+    @Test
+    void whenCastingNonStringAndCallingValueOf_thenGetExpectedResult() {
+        Object obj = 42;
+        assertThrows(ClassCastException.class, () -> {String castResult = (String) obj;});
+
+        String valueOfResult = String.valueOf(obj);
+        assertEquals("42", valueOfResult);
+
+        Object obj2 = List.of("Baeldung", "is", "awesome");
+        assertThrows(ClassCastException.class, () -> {String castResult = (String) obj2;});
+
+        valueOfResult = String.valueOf(obj2);
+        assertEquals("[Baeldung, is, awesome]", valueOfResult);
+    }
+
+    @Test
+    void whenObjectIsNullCastingAndCallingValueOf_thenGetExpectedResult() {
+        Object obj = null;
+        String castResult = (String) obj;
+        assertNull(castResult);
+
+        String valueOfResult = String.valueOf(obj);
+        assertNotNull(valueOfResult);
+        assertEquals("null", valueOfResult);
+    }
+}