What characterizes a constructor in Java?

A constructor in Java is a special method that is invoked when an instance of a class is created. Its primary purpose is to initialize the newly created object, often by setting initial values for the object's attributes or executing startup procedures. This characteristic distinguishes constructors from other methods in the class, as they do not have a return type, not even void, and must have the same name as the class they belong to.

The constructor's execution is automatically triggered whenever you create a new object using the new keyword. For example, if you have a class called Car, the constructor will run automatically whenever you create a new instance of Car, ensuring that the object is appropriately set up from the moment it is instantiated.

The other options present attributes that do not align with the definition and behavior of constructors in Java, thereby reinforcing the correctness of the selected answer.