Constructor execution flow in Java - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a constructor in Java?

A constructor is a special method in Java used to create and initialize objects. It has the same name as the class and no return type.

beginner

What happens first when a Java object is created?

The superclass constructor is called first before the subclass constructor runs. This ensures the parent part of the object is initialized first.

intermediate

How does Java decide which constructor to call in a class hierarchy?

Java calls constructors starting from the top superclass down to the subclass. Each constructor calls its superclass constructor using super(), either explicitly or implicitly.

intermediate

What is the role of the super() call in constructor execution?

super() calls the parent class constructor. If not written explicitly, Java inserts super() automatically as the first line in a constructor.

advanced

In what order are instance variables initialized during constructor execution?

Instance variables are initialized first in the order they appear, then the constructor body runs. This happens for each class from superclass to subclass.

When creating an object, which constructor runs first?

A Random constructor

B Subclass constructor

C Superclass constructor

D No constructor runs automatically

The superclass constructor runs first to initialize the parent part of the object.

What does Java insert automatically if a constructor does not call super() explicitly?

A super() call as the first line

B this() call as the first line

C No call is inserted

D A return statement

Java inserts super() automatically as the first statement to call the parent constructor.

Which of these is true about instance variable initialization during constructor execution?

A Variables initialize randomly

B Variables initialize before constructor body runs

C Variables never initialize automatically

D Variables initialize after constructor body runs

Instance variables are initialized first, then the constructor body executes.

If a subclass constructor calls super(), what does it do?

A Calls the superclass constructor

B Calls itself recursively

C Calls a method named super

D Does nothing

super() calls the constructor of the immediate parent class.

What is the order of constructor execution in a class hierarchy?

A Random order

B Subclass to superclass

C Only subclass constructor runs

D Top superclass to subclass

Constructors run from the top superclass down to the subclass.

Explain the flow of constructor execution when creating an object in Java.

Think about how Java builds an object from parent to child.

Describe what happens if you do not explicitly call super() in a subclass constructor.

Remember Java's default behavior for constructor chaining.