Cannot instantiate a nested class inside main()

Question

The simple code below generates an error:

non-static variable this cannot be referenced from a static context

What does this error mean? Ok I understand that this is a wrong syntax for instantiating the inner class objects.But I am not clear how I am "referencing non static variable this from a static context" by doing so."

public class Test{
    class Test1{}
    public static void main(String[] args) {
    // generates an error
    new Test1(); 
    }
}

does new Test1() in above code means this.new Test1();

you need an instance of outer class to do so, new Test().new Test1(); — Shailesh Aswal, Jul 09 '15 at 07:10
possible duplicate of [Java inner class and static nested class](http://stackoverflow.com/questions/70324/java-inner-class-and-static-nested-class) — RealSkeptic, Jul 09 '15 at 07:18

score 2 · Accepted Answer · answered Jul 09 '15 at 07:21

2

If the application requirements allow you to make the class Test1 a static class, then do this.

public class Test {

    static class Test1 {
    }

    public static void main(String[] args) {
        new Test.Test1();
    }
}

If the class Test1 needs to be non-static, then do this.

public class Test {

    class Test1 {
    }

    public static void main(String[] args) {
        new Test().new Test1();
    }
}

Notice the syntax of the instantiation in both the cases.

answered Jul 09 '15 at 07:21

Shrinivas Shukla

4,325
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If i simply do new Test1() as in my question then is it equivalent to this.newTest1() ? – hermit Jul 09 '15 at 07:37
FIrst point..... You cannot access `this` in `main()` beacause `this` is non-static and you **CANNOT** access non-static member from any static method. Second point...... if `class Test1` is `static`, then you can access it directly from `main()`.. In this case, `new Test.Test1()` and `new Test1()` is same. – Shrinivas Shukla Jul 09 '15 at 10:50

score 0 · Answer 2 · answered Jul 09 '15 at 07:17

0

You can see below code:

public class Test {

static class Test1 {
}

public static void main(String[] args) {

    Test.Test1 obj = new Test.Test1();
}}

answered Jul 09 '15 at 07:17

Rafiq

740
1
5
17

score 0 · Answer 3 · answered Jul 09 '15 at 07:18

0

You have to have a reference to the outer class Test as well.

Test1 inner = new Test().new Test1();

If inner Test1 was static then it would be

 Test1 inner = Test.new Test1();

answered Jul 09 '15 at 07:18

AnkeyNigam

2,810
4
15
23

Cannot instantiate a nested class inside main()

3 Answers3