All Flashcards
What is the process of calling a superclass constructor from a subclass?
- Define the subclass constructor. 2. Use the 'super()' keyword as the first statement. 3. Pass the appropriate arguments to 'super()' to match the superclass constructor's parameters.
What is the step-by-step process when a subclass object is created?
- Subclass constructor is called. 2. 'super()' is implicitly/explicitly called. 3. Superclass constructor executes. 4. Superclass instance variables are initialized. 5. Subclass instance variables are initialized. 6. Subclass constructor finishes executing.
What are the steps involved in the implicit call to superclass constructor?
- Subclass constructor is invoked without explicit 'super()'. 2. Java compiler automatically inserts 'super()' as the first line. 3. The no-argument constructor of the superclass is called.
What steps are involved in initializing a subclass using the superclass constructor?
- Define subclass constructor. 2. Call superclass constructor using 'super()'. 3. Initialize subclass-specific variables after the 'super()' call.
What is the process of constructor chaining?
- Subclass constructor calls 'super()'. 2. Superclass constructor executes, potentially calling its own 'super()'. 3. This continues up the inheritance hierarchy until the Object class constructor is called.
What are the steps to determine if a subclass constructor needs to explicitly call 'super()'
- Check if the superclass has a no-argument constructor. 2. If no no-argument constructor exists, an explicit call to 'super()' with appropriate arguments is required.
What steps are involved in handling exceptions during superclass constructor calls?
- If the superclass constructor throws an exception, the subclass constructor must handle it (either catch or declare it). 2. Ensure proper cleanup if an exception occurs during superclass initialization.
What is the process of initializing inherited instance variables using the superclass constructor?
- Pass the necessary values to the 'super()' call. 2. The superclass constructor will then assign these values to the inherited instance variables.
What are the steps to create a subclass constructor that takes parameters for both superclass and subclass instance variables?
- Define the subclass constructor with parameters for both. 2. Call 'super()' with parameters intended for the superclass. 3. Initialize the subclass-specific instance variables.
What is the process of ensuring proper initialization order when using 'super()'
- Always call 'super()' as the first statement. 2. This guarantees that the superclass is initialized before the subclass attempts to use any inherited members.
What are the differences between explicit and implicit calls to the superclass constructor?
Explicit: uses 'super()', programmer-defined arguments | Implicit: auto-inserted by Java, no-argument constructor
What are the differences between calling 'super()' with arguments and calling it without arguments?
With arguments: calls a specific superclass constructor with matching parameters | Without arguments: calls the no-argument constructor of the superclass
What are the differences between initializing instance variables in a superclass constructor vs. a subclass constructor?
Superclass: initializes inherited variables | Subclass: initializes variables specific to the subclass
What are the differences between the roles of the superclass and subclass constructors in object creation?
Superclass: initializes the inherited state and behavior. Subclass: Extends the superclass and initializes its own state and behavior.
What are the differences between the effects of calling 'super()' and not calling 'super()' in a subclass constructor?
Calling 'super()': ensures superclass initialization | Not calling 'super()': relies on implicit call to no-argument constructor (if it exists), may lead to errors if it doesn't exist.
What are the differences between how constructors are inherited vs. how methods are inherited?
Constructors: are not inherited, must be explicitly called using 'super()' | Methods: are inherited and can be overridden.
What are the differences between the purpose of a constructor in a superclass versus a subclass?
Superclass: initializes the common state of all its subclasses. Subclass: initializes its own state and potentially extends the superclass's state.
What are the differences between the flexibility of explicit vs. implicit superclass constructor calls?
Explicit: allows choosing which superclass constructor to call with specific arguments. Implicit: only calls the no-argument constructor.
What are the differences between the consequences of an exception thrown in a superclass constructor vs. a subclass constructor?
Superclass: can prevent the entire object from being created if not handled. Subclass: can be handled within the subclass, allowing partial object creation or alternative initialization.
What are the differences between the visibility of constructors in superclasses vs. subclasses?
Superclass: determines who can create instances of the superclass directly. Subclass: inherits visibility rules but can only call the superclass constructor through 'super()'.
What is the definition of 'Superclass'?
A class from which other classes (subclasses) inherit attributes and methods.
What is the definition of 'Subclass'?
A class that inherits attributes and methods from another class (superclass).
What is the definition of the 'super' keyword?
A keyword used to call the superclass's constructor or access its members from the subclass.
What is the definition of 'Constructor'?
A special method used to initialize objects of a class.
What is the definition of 'Inheritance'?
A mechanism where a class acquires the properties (attributes and methods) of another class.
What is the definition of 'No-argument constructor'?
A constructor that takes no arguments.
What is the definition of 'Explicit constructor call'?
A constructor call made directly in the code, using the 'super' keyword.
What is the definition of 'Implicit constructor call'?
A constructor call automatically inserted by the compiler when no explicit call is made.
What is the definition of 'Object class'?
The ultimate superclass of all classes in Java.
What is the definition of 'Instance variable'?
A variable defined in a class (i.e., a member variable) for which every object of the class has its own copy.