[BAEL-5661] Integer.toString vs String.valueOf (#12591)

* Initial commit for Object copy in Java

* review comments commit for Object copy in Java

* Initial commit for parseInt vs valueOf java

* Review comments commit for parseInt vs valueOf java

* Modify readme

* review comments

* build failure

* build failure retry

* build failure retry remove parseInt(java.lang.String,int,int,int)

* build failure add comment

* change examples

* review comments

* review comments 2

* review comments 3

* Initial commit for get current stacktrace

* Remove old files

* Name updates

* Jenkins error

* changes to file name

* Review comments

* Create unit test file

* Remove unnecessary files

core-java-modules/core-java-string-conversions-2/src/test/java/com/baeldung/inttostring/IntToStringUnitTest.java

@@ -0,0 +1,29 @@
+package com.baeldung.chararraytostring;
+
+import static org.junit.Assert.assertEquals;
+
+import org.junit.Test;
+
+public class IntToStringUnitTest {
+
+    @Test
+    public void whenValidIntIsPassed_thenShouldConvertToString() {
+        assertEquals("11", Integer.toString(11)); 
+        assertEquals("11", Integer.toString(+11)); 
+        assertEquals("-11", Integer.toString(-11));
+    }
+    
+    @Test
+    public void whenValidIntIsPassed_thenShouldConvertToValidString() {
+        assertEquals("11", String.valueOf(11)); 
+        assertEquals("11", String.valueOf(+11));
+        assertEquals("-11", String.valueOf(-11));
+    }
+    
+    @Test(expected = NullPointerException.class)
+    public void whenNullIntegerObjectIsPassed_thenShouldThrowException() {
+        Integer i = null;
+        System.out.println(String.valueOf(i)); // it prints "null"
+        System.out.println(i.toString()); 
+    }
+}