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The constructor of a Java class is not an ordinary method. Its purpose is not to return any value. The purpose of the constructor is to instantiate the class which it does.
Since, the purpose of a constructor is only to instantiate and initialize its class and not anything else, it does not have a return type. All it does is creates an object of that class.
What else can I help you with?
What is return data type?
A Constructor in java cannot have a return type. It always creates and returns an object of the class for which it is the constructor. You cannot return a value from a constructor explicitly and if you try to do that, the compiler will give an error. The system knows that the purpose of the constructor is to create an object of the class and it will do the same irrespective of whether you declare a return type or not.
What is the difference between the constructor to and destructor?
Functions and Constructors are similar in many ways. They can have arguments, they can have any amount of code, they can access the class's variables etc. the only difference is that a method in java needs to mandatorily have a return type but a Constructor in java cannot have a return type. It always creates and returns an object of the class for which it is the constructor. You cannot return a value from a constructor explicitly and if you try to do that, the compiler will give an error. The system knows that the purpose of the constructor is to create an object of the class and it will do the same irrespective of whether you declare a return type or not.
Why you don't use void in constructor function although it doesn't return any value?
Return a value in the constructor is senseless, because a constructor is used to initialize a object instance and not to perform a task or a operation. When we call a constructor we used a sentence like this: MyClass var = new MyClass(); Then when we execute the above line the constructor return ('create') a new object of the type 'MyClass'. If this call could return an other type, for example an Integer, the constructor is considered a normal method, and if there are not more constructors a empty default constructor for MyClass is defined by the java compiler. public class MyClass{ // The java compiler will insert a real constructor here public Integer MyClass(){ //This isn't a constructor, only a simple method return new Integer(1); } }
Characteristics of constructor?
Contains an access modifier followed by the name of the class and some parameters. More specifically: public class MyClass { //Constructor public MyClass() { } }
What are the rules on how to construct java constructor?
1. The constructor has to have the same name as the classthat it is in.2. It does not have a return type. If it has a return type, then it is a method (even though it is legal, it's not ideal to have name a method the same name as the class).3. It can use any access modifier (this includes private).4. The default constructor does not take arguments.5. The first statement in a constructor has to have a super() type or this() type. If this is not written, by default, it's super(). It's illegal to have it in any other line other than the first line.6. Constructors can only access static variables.7. Only constructors have access to another constructor.Remember that interfaces do not have a constructor.
What is return data type?
A Constructor in java cannot have a return type. It always creates and returns an object of the class for which it is the constructor. You cannot return a value from a constructor explicitly and if you try to do that, the compiler will give an error. The system knows that the purpose of the constructor is to create an object of the class and it will do the same irrespective of whether you declare a return type or not.
What is the difference between the constructor to and destructor?
Functions and Constructors are similar in many ways. They can have arguments, they can have any amount of code, they can access the class's variables etc. the only difference is that a method in java needs to mandatorily have a return type but a Constructor in java cannot have a return type. It always creates and returns an object of the class for which it is the constructor. You cannot return a value from a constructor explicitly and if you try to do that, the compiler will give an error. The system knows that the purpose of the constructor is to create an object of the class and it will do the same irrespective of whether you declare a return type or not.
Why you don't use void in constructor function although it doesn't return any value?
Return a value in the constructor is senseless, because a constructor is used to initialize a object instance and not to perform a task or a operation. When we call a constructor we used a sentence like this: MyClass var = new MyClass(); Then when we execute the above line the constructor return ('create') a new object of the type 'MyClass'. If this call could return an other type, for example an Integer, the constructor is considered a normal method, and if there are not more constructors a empty default constructor for MyClass is defined by the java compiler. public class MyClass{ // The java compiler will insert a real constructor here public Integer MyClass(){ //This isn't a constructor, only a simple method return new Integer(1); } }
What is the difference between consructor and function in java?
Functions and Constructors are similar in many ways. They can have arguments, they can have any amount of code, they can access the class's variables etc. the only difference is that a method in java needs to mandatorily have a return type but a Constructor in java cannot have a return type. It always creates and returns an object of the class for which it is the constructor. You cannot return a value from a constructor explicitly and if you try to do that, the compiler will give an error. The system knows that the purpose of the constructor is to create an object of the class and it will do the same irrespective of whether you declare a return type or not.
What are special properies of constructor in java class?
Two key points to remember about constructors are that they have no return type and their names must exactly match the class name
What is a nonparameterised constructor in java?
Every class, including abstract classes, MUST have a constructor. But just because a class must have one, doesn't mean the programmer has to type it. A constructor looks like this: class Car { Car() { } // The constructor for the Car class } You notice anything missing in the declaration above? There's no return type! Two key points to remember about constructors are that they have no return type and their names must exactly match the class name. The above car() is the non-parameterised or no-arg constructor for the class.
Characteristics of constructor?
Contains an access modifier followed by the name of the class and some parameters. More specifically: public class MyClass { //Constructor public MyClass() { } }
What are the rules on how to construct java constructor?
1. The constructor has to have the same name as the classthat it is in.2. It does not have a return type. If it has a return type, then it is a method (even though it is legal, it's not ideal to have name a method the same name as the class).3. It can use any access modifier (this includes private).4. The default constructor does not take arguments.5. The first statement in a constructor has to have a super() type or this() type. If this is not written, by default, it's super(). It's illegal to have it in any other line other than the first line.6. Constructors can only access static variables.7. Only constructors have access to another constructor.Remember that interfaces do not have a constructor.
What is the return type of finally method in java?
The final and finally keywords have no impact on the return type of a method in Java.
Why constructors does not have return type in java?
A return type for a method is used when you invoke the method; for example: SomeClass x = new SomeClass(); int someInterestingResult = x.SomeCalculation(); Note that here, the result (return value) of the method "SomeCalculation" is assigned to the variable someInterestingResult. You might also show it directly on screen: System.out.println(x.SomeCalculation()); However, in the case of a constructor, it doesn't really make sense to assign it to a variable. In the above example: x = new SomeClass(); the variable "x" will not hold any return value of a method; rather, it will hold a pointer to the newly created object. A special syntax (which Java doesn't have) would be required to hold the return value of the constructor. In any case, the purpose of the constructor is usually to build the object, not to immediately return any value.
How do we invoke a constructor?
In Java, objects are constructed. Every time you make a new object, at least one constructor is invoked. Every class has a constructor, although if you don't create one explicitly, the compiler will build one for you. Ex: class Test { public Test() { } // this is Test's constructor public void Test() { } // this is a badly named, // but legal, method } If you see the example above, you would have realized that the constructor looks a lot like methods. Below are the main distinguishing factors between the constructor and normal methods: 1. The Constructor's name is exactly the same as the name of the class 2. They do not have a return type (Please remember this. A Constructor cannot have a return type as part of the code) 3. Constructors cannot be static, abstract or final
Difference between method and constructor in java?
A constructor is technically a type of method, but it is a very special type. Whereas other methods can be used to do just about anything, the only purpose of a constructor method is to create an instance of the class that contains it, often with parameters passed to it through another part of the program. This instance is called an "object" and is a central part of not only Java, but other object-oriented languages as well. A constructor method always has the same name as its containing class, and does not have a return type. Think of it this way: a class in Java is like a generic blueprint for a house. Your instance variables are like different attributes of the house - how many bathrooms will your house have, what colour will it be? Once you decide on the exact specifications for your house, you can give those parameters to the construction company, which will actually create that house. That's what a constructor method does - takes input parameters (or, lacking them, sets defaults) and creates an object.
