Interview questions

No, we cannot call subclass constructor from superclass constructor. Example class SuperClass{ SuperClass(){ System.out.println("SuperClass constructor"); SubClass(); } } public class SubClass extends SuperClass { SubClass (){ System.out.println("Subclass constructor"); } public static void main(String[] args) { System.out.println("Constructor test"); } }class SuperClass{ SuperClass(){ System.out.println("SuperClass constructor"); SubClass(); } } public class SubClass extends SuperClass { SubClass (){ System.out.println("Subclass … Read more

Parameterized constructor A constructor with one or more parameters is called as parameterized constructor. Why parameterized constructor is used? Parameterized constructor is used to provide the initial values to the object properties (initial state of object). By use of parameterized constructor different objects can be initialize with different data member values or states. Example /** … Read more

Constructor chaining is a process of calling a constructor from another constructor. We can use this() to call same class constructor and super() to call super class constructor. class SuperClass{ public SuperClass(int i){ System.out.println("Super class constructor"); } }   class SubClass extends SuperClass { public SubClass(){ //Calling same class constructor this(50); }   public SubClass(int … Read more

Yes, we can create an object without using new operator in java. Using newInstance() Method If we know the name of the class and it has a public default constructor than we can create an object in the following way. MyObject object = (MyObject) Class.forName("com.w3schools.MyObject").newInstance();MyObject object = (MyObject) Class.forName("com.w3schools.MyObject").newInstance(); Using clone() The clone() can be … Read more

The way of defining multiple constructor with different arguments in a specified class is called constructor overloading. Parameters can differ in type, number or order. Example /** * This program is used to show the use of constructor overloading. * @author w3schools */ public class ConstructorOverload { int rollNo; boolean isStudent; String name;     … Read more

Example /** * This program is used to copy the values one object into another object using constructor. * @author w3schools */ public class CopyValuesConstructor { int id; String name;   CopyValuesConstructor(int id, String name){ System.out.println("Constructor called."); this.id = id; this.name = name; }   //Copy value of one object into another. CopyValuesConstructor(CopyValuesConstructor obj){ System.out.println("Constructor … Read more

            Constructor               Method A Constructor has same name as of class. A Constructor invoked implicitly. A Constructor must not have any explicit return type. A Constructor is used to initialize the object’s state. A Method may or may not have same name as of class. A Method invoked explicitly. A Method must have … Read more

No, we cannot make constructor as final in java. For methods, final keyword is used to prevent them to be overridden by subclass. Constructors are also the special kind of methods but as we know that constructor can not be inherited in subclass, hence there is no use of final keyword with constructor. If we … Read more

Constructor Constructor is a block of statements that permits you to create an object of specified class and has similar name as class with no explicit  or specific return type. No, constructor cannot be inherited in java. In case of inheritance, child/sub class inherits the state (data members) and behavior (methods) of parent/super class. But … Read more

Constructor Constructor is a particular member of the specified class which is used to initialize the state of an object. It gives the values to the data members on the time of object creation that’s the reason it is named constructor. It does not have any explicit return type but it returns current instance of … Read more