I am struggling to fully understand the usage of constructors in Java.

What I have learned so far about constructors is the following:

• same name as class
• abbreviation ctor
• overloading
• no return type
• create an object of a class
• every class has a default constructor

When for example a string has to be returned from a class that needs to be called then a method could be created, i.e. a constructor will not be sufficient as this will not return anything.

Attempt to answer the question

In order to explain what I mean, I have created a class with two constructors and two methods that return a string.

public class HelloWorldConstructor {     public HelloWorldConstructor() { }      public HelloWorldConstructor(String a) {         saySomething(a);     }      public HelloWorldConstructor(String a, String b) {         saySomething(a, b);     }      void saySomething(String a) {         System.out.println(a);     }      void saySomething(String a, String b) {         System.out.println(a + ", " + b);     } } 

Option 1

It is possible to return a string by calling the method that resides in the class.

public class CallConstructor {     public static void main(String[] args) {         HelloWorldConstructor hwc = new HelloWorldConstructor();          hwc.saySomething("allo");         hwc.saySomething("allo", "allo");     } } 

returns:

allo allo, allo 

Option 2

It is also possible to return a string by calling the constructor directly.

public class CallConstructor2 {     public static void main(String[] args) {         new HelloWorldConstructor("allo");         new HelloWorldConstructor("allo", "allo");     } } 

returns the same as option 1.

Discussion

When option 2 is chosen, then two objects have to be created instead of one as depicted by option 1, but when to choose option 2 and when option 1? In this case I think it is better to choose option 1 as one object will be created, but option 2 could be suitable when other circumstances are applicable.

Using Constructors in Java

The constructor in the example just gives an initial value to class members.

https://stackoverflow.com/a/19941847/2777965

Constructors are used to initialize the instances of your classes. You use a constructor to create new objects often with parameters specifying the initial state or other important information about the object

After reading about theory and Q&As about constructors I am struggling to fully understand them. I know how to call a constructor and how to call a method, but I cannot rationalize this.

• A constructor has to be called directly when …
• Constructor overloading will be done when …
• Methods will be called directly by calling the default constructor when …