对象方法如何引用该对象的内部类？

public class OuterClass {
    private class InnerClass {
        public void innerMethod() {
            System.out.println("This is the inner method");
        }
    }
    
    public void outerMethod() {
        InnerClass inner = new InnerClass();
        inner.innerMethod();
    }
}

public class OuterClass {
    public static class InnerClass {
        public void innerMethod() {
            System.out.println("This is the inner method");
        }
    }
    
    public void outerMethod() {
        InnerClass inner = new OuterClass.InnerClass();
        inner.innerMethod();
    }
}

public class OuterClass {
    private class InnerClass {
        public void innerMethod() {
            System.out.println("This is the inner method");
        }
    }
}

public class Main {
    public static void main(String[] args) {
        OuterClass outer = new OuterClass();
        OuterClass.InnerClass inner = outer.new InnerClass();
        inner.innerMethod();
    }
}