Instantiate inner class object from current outer class object

Question

I am wondering if the following is valid in Java:

class OuterClass {

    OuterClass(param1, param2) {
        ...some initialization code...
    }

    void         


        

Answer 1

Every instance of an inner class, unless the Class is declared as static, must have a 'connected' instance of an outer class, in order to be instantiated.

This won't work:

public class Outer {
    public class Inner { 
    }
    public static void main(String[] args) {
        Inner inner = new Inner(); //compilation error
    }
}

However, this will work, it doesn't need an instance of Outer, since the static keyword is used:

public class Outer {
    public static class Inner { 
    }
    public static void main(String[] args) {
        Inner inner = new Inner(); 
    }
}

more info: java inner classes