We use constructors to initialize the object with the default or initial state. The default values for primitives may not be what are you looking for. Another reason to use constructor is that it informs about dependencies.
Why do we need to use constructors?
Constructors initialize the new object, that is, they set the startup property values for the object. They might also do other things necessary to make the object usable. You can distinguish constructors from other methods of a class because constructors always have the same name as the class.
Why are constructors needed in Java?
The purpose of constructor is to initialize the object of a class while the purpose of a method is to perform a task by executing java code. Constructors cannot be abstract, final, static and synchronised while methods can be. Constructors do not have return types while methods do.
Why do we need two constructors in Java?
To put it simply, you use multiple constructors for convenience (1st example) or to allow completely different initialization methods or different source types (2nd example. For example: Empty constructor (no arguments) for reflection, Constructor has argument(s) for create new instance ( A a = new A(‘foo’, ‘bar’); ).
Can a constructor be final?
Constructors are used to initialize an object. … It is syntactically similar to a method but it has the same name as its class and a constructor does not have a return type. Java constructor can not be final. One of the important property of java constructor is that it can not be final.
Can constructor be private?
A private constructor in Java is used in restricting object creation. It is a special instance constructor used in static member-only classes. If a constructor is declared as private, then its objects are only accessible from within the declared class. You cannot access its objects from outside the constructor class.
Why constructor is a special method?
In simple word, Constructor is a method like a block of code which is called by Java runtime during object creation using new() operator. Constructor are special in the sense that they have the same name as the Class they are part of.
Does constructor return a value?
Does constructor return any value? There are no “return value” statements in the constructor, but the constructor returns the current class instance.
Can we have 2 constructors in Java?
A class can have multiple constructors, as long as their signature (the parameters they take) are not the same. You can define as many constructors as you need. When a Java class contains multiple constructors, we say that the constructor is overloaded (comes in multiple versions).
Can you call a constructor?
Invoking a constructor from a method
No, you cannot call a constructor from a method. The only place from which you can invoke constructors using “this()” or, “super()” is the first line of another constructor. If you try to invoke constructors explicitly elsewhere, a compile time error will be generated.
Can multiple constructors have the same name?
A user can implement constructor overloading by defining two or more constructors in a class sharing the same name. C# can distinguish the constructors with different signatures. i.e. the constructor must have the same name but with different parameters list.
Why we Cannot 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.
Is constructor inherited?
Constructors are not members, so they are not inherited by subclasses, but the constructor of the superclass can be invoked from the subclass.
Can we execute a program without main?
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.