Updated MemoryLeaks article (#2184)

* Create memory-leaks module

* Memory Leaks

* Added str.intern()

* Memory Leaks updated

* Updated guest article

* Memory Leaks update

* Remove unused resource

guest/memory-leaks/src/test/java/com/baeldung/MemoryLeaksTest.java

@@ -26,21 +26,30 @@
 //@FixMethodOrder(MethodSorters.NAME_ASCENDING)
 //@RunWith(JUnit4.class)
 //public class MemoryLeaksTest {
-
 //    private Random random = new Random();
 //    public static final ArrayList<Double> list = new ArrayList<Double>(1000000);
 //
-//    @Test(expected = OutOfMemoryError.class)
+//    @Test
 //    public void givenStaticField_whenLotsOfOperations_thenMemoryLeak() throws InterruptedException {
-//        while (true) {
+//        for (int i = 0; i < 1000000; i++) {
-//            int k = random.nextInt(100000);
+//            list.add(random.nextDouble());
-//            System.out.println(k);
-//            Thread.sleep(10000); //to allow GC do its job
-//            for (int i = 0; i < k; i++) {
-//                list.add(random.nextDouble());
-//            }
 //        }
+//        Thread.sleep(10000); //to allow GC do its job
+//    }
 //
+//    
+//    @Test
+//    public void givenNormalField_whenLotsOfOperations_thenGCWorksFine() throws InterruptedException {
+//        addElementsToTheList();
+//        System.gc();
+//        Thread.sleep(10000); //to allow GC do its job
+//    }
+//    
+//    private void addElementsToTheList(){
+//        ArrayList<Double> list = new ArrayList<Double>(1000000);
+//        for (int i = 0; i < 1000000; i++) {
+//            list.add(random.nextDouble());
+//        }
 //    }
 //
 //    @SuppressWarnings({ "resource" })
@@ -51,11 +60,11 @@
 //        str.intern();
 //        System.out.println("Done");
 //    }
-
+//
 //    @Test(expected = OutOfMemoryError.class)
 //    public void givenURL_whenUnclosedStream_thenOutOfMemory() throws IOException, URISyntaxException {
 //        String str = "";
-//        URLConnection conn = new URL("http://norvig.com/big.txt").openConnection();
+//        URLConnection conn = new URL("http:norvig.com/big.txt").openConnection();
 //        BufferedReader br = new BufferedReader(new InputStreamReader(conn.getInputStream(), StandardCharsets.UTF_8));
 //        while (br.readLine() != null) {
 //            str += br.readLine();
@@ -66,7 +75,7 @@
 //    @SuppressWarnings("unused")
 //    @Test(expected = OutOfMemoryError.class)
 //    public void givenConnection_whenUnclosed_thenOutOfMemory() throws IOException, URISyntaxException {
-//        URL url = new URL("ftp://speedtest.tele2.net");
+//        URL url = new URL("ftp:speedtest.tele2.net");
 //        URLConnection urlc = url.openConnection();
 //        InputStream is = urlc.getInputStream();
 //        String str = "";