BAEL-6819 convert from int to Long in Java (#14671)

* BAEL-6819 convert from int to Long in Java

* BAEL-6819 update package name

core-java-modules/core-java-numbers-conversions/src/test/java/com/baeldung/inttolong/IntToLongUnitTest.java

@@ -0,0 +1,36 @@
+package com.baeldung.inttolong;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.junit.jupiter.api.Test;
+
+class IntToLongUnitTest {
+
+    @Test
+    void whenUsingTheAutoboxing_thenGetTheExpectedLong() {
+        int intTen = 10;
+        Long longTen = (long) intTen;
+        assertEquals(intTen, longTen);
+    }
+
+    @Test
+    void whenUsingTheValueOf_thenGetTheExpectedLong() {
+        int intTen = 10;
+        Long longTen = Long.valueOf(intTen);
+        assertEquals(intTen, longTen);
+    }
+
+    @Test
+    void whenUsingTheConstructor_thenGetTheExpectedLong() {
+        int intTen = 10;
+        Long longTen = new Long(intTen);
+        assertEquals(intTen, longTen);
+    }
+
+    @Test
+    void whenUsingTheParseLong_thenGetTheExpectedLong() {
+        int intTen = 10;
+        Long longTen = Long.parseLong(String.valueOf(intTen));
+        assertEquals(intTen, longTen);
+    }
+}