BAEL-5131: constructor specification is added c (#11586)

* BAEL-5131: constructor specification is added c

* BAEL-5131: codes have been reformatted

* BAEL-5131: I've added a few minor changes over on this package.

* BAEL-5131: I've added a few minor changes over on this package.

core-java-modules/core-java-lang-oop-constructors/src/main/java/com/baeldung/constructorspecification/rules/Employee.java

@@ -0,0 +1,24 @@
+package com.baeldung.constructorspecification.rules;
+
+class Employee extends Person {
+
+    int id;
+
+    public Employee() {
+        super();
+    }
+
+    public Employee(String name) {
+        super(name);
+    }
+
+    public Employee(int id) {
+        this();
+        //super("John"); // syntax error
+        this.id = id;
+    }
+
+    public static void main(String[] args) {
+        new Employee(100);
+    }
+}

core-java-modules/core-java-lang-oop-constructors/src/main/java/com/baeldung/constructorspecification/rules/Person.java

@@ -0,0 +1,14 @@
+package com.baeldung.constructorspecification.rules;
+
+class Person {
+
+    String name;
+
+    public Person() {
+        this("Arash");
+    }
+
+    public Person(String name) {
+        this.name = name;
+    }
+}

core-java-modules/core-java-lang-oop-constructors/src/main/java/com/baeldung/constructorspecification/rules/RecursiveConstructorInvocation.java

@@ -0,0 +1,12 @@
+package com.baeldung.constructorspecification.rules;
+
+class RecursiveConstructorInvocation {
+
+    public RecursiveConstructorInvocation() {
+        RecursiveConstructorInvocation rci = new RecursiveConstructorInvocation();
+    }
+
+    public static void main(String[] args) {
+        new RecursiveConstructorInvocation(); // java.lang.StackOverflowError
+    }
+}

core-java-modules/core-java-lang-oop-constructors/src/main/java/com/baeldung/constructorspecification/simple/Person.java

@@ -0,0 +1,14 @@
+package com.baeldung.constructorspecification.simple;
+
+class Person {
+
+    String name;
+
+    public Person() {
+        this("Arash");   //ExplicitConstructorInvocation
+    }
+
+    public Person(String name) {
+        this.name = name;
+    }
+}

core-java-modules/core-java-lang-oop-constructors/src/main/java/com/baeldung/constructorspecification/superclass/Employee.java

@@ -0,0 +1,15 @@
+package com.baeldung.constructorspecification.superclass;
+
+class Employee extends Person {
+
+    String name;
+
+    public Employee(int id) {
+        super(id);   //ExplicitConstructorInvocation
+    }
+
+    public Employee(int id, String name) {
+        super(id);
+        this.name = name;
+    }
+}

core-java-modules/core-java-lang-oop-constructors/src/main/java/com/baeldung/constructorspecification/superclass/Person.java

@@ -0,0 +1,10 @@
+package com.baeldung.constructorspecification.superclass;
+
+class Person {
+
+    int id;
+
+    public Person(int id) {
+        this.id = id;
+    }
+}