Frequent question: Can a Java class not have a constructor?

It is possible for a class to have no constructor. (An important distinction to draw here is that the JVM does not require all class files to have a constructor; however, any class defined in Java does have a default constructor if a constructor is not explicitly declared.

What happens if there is no constructor defined in a class?

If we don’t define a constructor in a class, then the compiler creates default constructor(with no arguments) for the class. And if we write a constructor with arguments or no-arguments then the compiler does not create a default constructor.

Do all Java classes need a constructor?

Java doesn’t require a constructor when we create a class. … The compiler automatically provides a public no-argument constructor for any class without constructors. This is called the default constructor.

Can a class work without a constructor?

When we create instance of a class a default constructor is invoked automatically having the same name as Class . Some key points, Constructor is used to initialize an object (instance) of a class. Constructor is a like a method without any return type.

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What if there is no constructor in Java?

Java does not actually require an explicit constructor in the class description. If you do not include a constructor, the Java compiler will create a default constructor in the byte code with an empty argument.

Why do we need constructor in Java?

A Java constructor is special method that is called when an object is instantiated. In other words, when you use the new keyword. The purpose of a Java constructor is to initializes the newly created object before it is used.

When a program does not contain any constructor Java compiler provides a constructor?

It calls a default constructor if there is no constructor available in the class. In such case, Java compiler provides a default constructor by default. There are two types of constructors in Java: no-arg constructor, and parameterized constructor.

Can a class have no default constructor?

No default constructor is created for a class that has any constant or reference type members. If any of the above are false, then the constructor is nontrivial. A union member cannot be of a class type that has a nontrivial constructor. Like all functions, a constructor can have default arguments.

Does Java have default constructor?

Java compiler automatically creates a default constructor (Constructor with no arguments) in case no constructor is present in the java class. Initialize all the instance variables of the class object. …

Do you always need a default constructor?

@Jos You don’t have to create a default constructor, if you don’t want one. But if you do want one, you’ll have to provide it yourself (or make it = default ).

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Does every class have a constructor?

Every class has a constructor whether it’s a normal class or a abstract class. Constructors are not methods and they don’t have any return type. Constructor name should match with class name . Constructor can use any access specifier, they can be declared as private also.

What happens if there is no constructor defined inside a class Mcq?

What happens if a user forgets to define a constructor inside a class? Explanation: The C++ compiler always provides a default constructor if one forgets to define a constructor inside a class.

What happens if you don’t create a constructor for a class Mcq?

If you don’t define a constructor for a class, a default parameterless constructor is automatically created by the compiler. The default constructor calls super() and initializes all instance variables to default value like 0, null.

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