CODEWITHSUNDEEP
java
GM Kart
GM Kart

Reputation: 13

Compilation error when using inner class

Currently learning about inner class. I have two classes. In second class there is an inner class. I am trying to create an object of the inner class in the second class. But I am getting compilation error. Can anyone help?

Here is my code:

public class MainClass {

    public static void main(String[] args) {

        NestedClass.NewUser newUserObj = new NewUser("User");
        System.out.println(newUserObj.Name);
    }
}

class NestedClass {

    class NewUser {
        public String Name;

        NewUser(String name) {
            this.Name = name;
        }
    }
}

Upvotes: 1

Views: 146

Answers (4)

Ryan Stewart
Ryan Stewart

Reputation: 128829

Alternate option: make the inner class static. Then, technically, it's no longer an "inner" class but only a "nested" class, and you can instantiate it with new NestedClass.NewUser(). As explained in the Nested Classes Tutorial, static nested classes can be instantiated without having an instance of the enclosing class, like the other answers refer to.

Upvotes: 2

Reimeus
Reimeus

Reputation: 159784

Despite the name NestedClass is not a nested class but rather an outer class, so an instance of NestedClass is required to create an instance of the real nested class, i.e. NewUser

NestedClass.NewUser newUserObj = new NestedClass().new NewUser("User");

Upvotes: 2

Sotirios Delimanolis
Sotirios Delimanolis

Reputation: 279970

You can only create an instance of NewUser with an instance of NestedClass.

new NestedClass().new NewUser("User");

Upvotes: 2

Gokul Nath KP
Gokul Nath KP

Reputation: 15553

To instantiate an inner class, you must first instantiate the outer class.

Create the inner object using the outer object as shown below:

NestedClass.NewUser newUserObj = (new NestedClass()).new NewUser("User");

Reference: http://docs.oracle.com/javase/tutorial/java/javaOO/nested.html

Upvotes: 6

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