Which keyword is used to call parent class constructor and method from within the class?
Ngày đăng:
30/10/2022
Trả lời:
0
Lượt xem:
74
Show
Core ConceptsInheritance has the same core concepts in any object-oriented language
Inheritance in JavaUse the keyword extends to declare the derived class// Example 1 public class AAA // AAA is the base class { ... } public class BBB extends AAA // BBB is the derived class { ... } // Example 2 public class Employee {...} // base class public class HourlyEmployee extends Employee { ... } // derived keyword superYou can use super like a function call in a derived class constructor -- invokes the base class constructorsuper(); // invokes base class default constructor super(parameters); // invokes base class constructor with parameters // Example, for a class called HourlyEmployee, derived from Employee public class HourlyEmployee extends Employee { public HourlyEmployee() // default constructor { super(); // invokes Employee() constructor } public HourlyEmployee(double h, double r) { super(h,r); // invokes Employee constructor w/ 2 parameters } // ... more methods and data } // end class HourlyEmployee
The protected modifier
The final modifierUse in Java for a few special inheritence-related purposes:
Other differences
Method OverridingJust like in C++, this is when a derived class has a method with the same prototype as a method in the base class. (The derived class function overrides the base class version, when called for a derived object).Example:
Abstract Classes
Which keyword is used to call methods of the parent class?Use of super with methods
This is used when we want to call the parent class method. So whenever a parent and child class have the same-named methods then to resolve ambiguity we use the super keyword.
Which keyword can be used to call the constructor of a parent class?For calling the constructor of a parent class we can use the super keyword. The super() method from the constructor method is used for the invocation of the constructor method of the parent class to get access to the parent's properties and methods.
Which keyword is used to access the method constructor or variable of parent class?The super keyword in Java helps subclasses (or child classes) to access members (data members, methods, and constructors) of the superclass (or parent class). In short, it's a keyword that is used to access parent class objects.
What is the keyword use to call parent constructor methods Java?Use of super() to access superclass constructor
As we know, when an object of a class is created, its default constructor is automatically called. To explicitly call the superclass constructor from the subclass constructor, we use super() . It's a special form of the super keyword.
|