BAEL-7131 version 4 - code review comments.

core-java-modules/core-java-io-apis-2/src/test/java/com/baeldung/inputstream/InputStreamTest.java

@@ -1,14 +1,21 @@
 package com.baeldung.inputstream;
 
+import static org.junit.jupiter.api.io.CleanupMode.ALWAYS;
+
 import java.io.ByteArrayInputStream;
 import java.io.File;
 import java.io.FileInputStream;
+import java.io.FileOutputStream;
 import java.io.IOException;
 import java.io.InputStream;
+import java.io.ObjectInputStream;
+import java.io.ObjectOutputStream;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.util.Arrays;
+import java.util.HashMap;
 import java.util.List;
+import java.util.Map;
 
 import org.junit.Assert;
 import org.junit.jupiter.api.Test;
@@ -64,4 +71,28 @@ public class InputStreamTest {
         }
         return sb.toString();
     }
+
+    @Test
+    public void givenKeyValuePairs_whenWrittenInATextFile_thenSuccessWhenParsedWithObjectInputStream(
+          @TempDir(cleanup = ALWAYS) Path tempDir) throws IOException, ClassNotFoundException {
+        Path sampleOut = tempDir.resolve("sample-out.txt");
+        File fileText = sampleOut.toFile();
+        //Serialize a Hashmap then write it into a file.
+        Map<String, String> kv = new HashMap<>();
+        try (FileOutputStream fileOutStream = new FileOutputStream(fileText)) {
+            try (ObjectOutputStream objectOutStream = new ObjectOutputStream(fileOutStream)) {
+                kv.put("baseURL", "baeldung.com");
+                kv.put("apiKey", "this_is_a_test_key");
+                objectOutStream.writeObject(kv);
+            }
+        }
+        //Deserialize the contents of a file then transform it back into a Hashmap
+        try (FileInputStream fileStream = new FileInputStream(fileText)) {
+            try (ObjectInputStream input = new ObjectInputStream(fileStream)) {
+                HashMap<String, String> inputKv = (HashMap<String, String>) input.readObject();
+                Assert.assertEquals(kv.get("baseURL"), inputKv.get("baseURL"));
+                Assert.assertEquals(kv.get("apiKey"), inputKv.get("apiKey"));
+            }
+        }
+    }
 }