Can we use this () and super () in a constructor?

Both “super” and “this” keywords in Java can be used in constructor chaining to call another constructor. “this()” calls the no-argument constructor of the current class, and “super()” calls the no-argument constructor of the parent class.

Can we use this () and super () in same method?

Use of both super() and this() are restricted by the condition that they can be used only as the first statement of a constructor. Both cannot be the first statement at the same time and so cannot be used together in the same constructor.

Can we use this () and super () in a method in Java?

No. this keyword mainly represents the current instance of a class. On other hand super keyword represents the current instance of a parent class. this keyword used to call default constructor of the same class.

Where super () can be used within a constructor?

super() can be used to invoke immediate parent class constructor.

Why super is used in constructor react?

super() will call the constructor of its parent class. This is required when you need to access some variables from the parent class. Hope this helps!

Java Super Keyword Tutorial - Super Keyword for Variables, Constructors and Methods

Do you have to call super in constructor?

However, using super() is not compulsory. Even if super() is not used in the subclass constructor, the compiler implicitly calls the default constructor of the superclass.

Why can't we use super and this in static method?

Where the "super" keyword in Java is used as a reference to the object of the superclass. This implies that to use "super" the method should be invoked by an object, which static methods are not. Therefore, you cannot use the "super" keyword from a static method.

Can we write static public void main String args?

Yes, we can change the order of public static void main() to static public void main() in Java, the compiler doesn't throw any compile-time or runtime error. In Java, we can declare access modifiers in any order, the method name comes last, the return type comes second to last and then after it's our choice.

Can we use this keyword in static method?

No, we can't use “this” keyword inside a static method. “this” refers to current instance of the class. But if we define a method as static , class instance will not have access to it, only CLR executes that block of code. Hence we can't use “this” keyword inside static method.

Can we use this in constructor?

It can be used inside the method or constructor of a class. It(this) works as a reference to the current object, whose method or constructor is being invoked. This keyword can refer to any member of the current object from within an instance method or a constructor.

Can we use this keyword in static constructor?

Return types of constructors are restricted to return the same type as that of the object. We cannot use static constructors in subclass construction as the implementation of only superclass constructors is allowed. A static constructor does not allow the use of “this” keyword to access an instance.

Can we use this inside static class?

No, we can not used "this" keyword within a static method. because "this" keyword refers to the current instance of the class. Static Member functions do not have a this pointer (current instance). Note - we can also not used "base" keyword within a static method.

Can we override static method?

Overloading is the mechanism of binding the method call with the method body dynamically based on the parameters passed to the method call. Static methods are bonded at compile time using static binding. Therefore, we cannot override static methods in Java.

Can we overload main method?

Yes, we can overload the main method in Java, but When we execute the class JVM starts execution with public static void main(String[] args) method.

Can abstract class have static variable in it?

Type of variables: Abstract class can have final, non-final, static and non-static variables.

Can abstract classes have static methods?

Yes, of course you can define the static method in abstract class. you can call that static method by using abstract class,or by using child class who extends the abstract class. Also you can able to call static method through child class instance/object.

Can a static method call non static method?

Characteristics of Static Methods

A static method can call only other static methods; it cannot call a non-static method. A static method can be called directly from the class, without having to create an instance of the class. A static method can only access static variables; it cannot access instance variables.

Can we use this keyword in main method?

Since the static methods doesn't have (belong to) any instance you cannot use the "this" reference within a static method. If you still, try to do so a compile time error is generated. And main method is static therefore, you cannot use the "this" reference in main method.

Can abstract methods have constructor?

Like any other classes in Java, abstract classes can have constructors even when they are only called from their concrete subclasses.

What happens if super () is not coded?

If we call "super()" without any superclass

Actually, nothing will be displayed. Since the class named Object is the superclass of all classes in Java. If you call "super()" without any superclass, Internally, the default constructor of the Object class will be invoked (which displays nothing).

Can we override constructor in Java?

It does not have a return type and its name is same as the class name. But, a constructor cannot be overridden. If you try to write a super class's constructor in the sub class compiler treats it as a method and expects a return type and generates a compile time error.

Can constructor be private?

Yes, we can declare a constructor as private. If we declare a constructor as private we are not able to create an object of a class. We can use this private constructor in the Singleton Design Pattern.

Can we overload final method?

Can We Override a Final Method? No, the Methods that are declared as final cannot be Overridden or hidden.

Can we execute a class without a main method?

Yes, we can execute a java program without a main method by using a static block. Static block in Java is a group of statements that gets executed only once when the class is loaded into the memory by Java ClassLoader, It is also known as a static initialization block.

Can we override final method?

Any method that is declared as final in the superclass cannot be overridden by a subclass.