You can restrict a class to make it's "n" number of object , please follow the below mentiond code.

public final class NnumberInstance {

private static NnumberInstance obj[];

private NnumberInstance() {

}

public static NnumberInstance[] getInstance(int n) {
    obj = new NnumberInstance[n];
    for (int i = 0; i < n; i++) {
        obj[i] = new NnumberInstance();
    }
    return obj;

}

}

public static NnumberInstance obj[];

public static void main(String[] args) {

    obj = NnumberInstance.getInstance(5);

    for (NnumberInstance instance : obj) {
        System.out.println("------------------------"+instance.hashCode());
    }

}

}

public final class NnumberInstance {

    private static NnumberInstance obj[];

    private NnumberInstance() {

    }

    public static NnumberInstance[] getInstance(int n) {
        obj = new NnumberInstance[n];
        for (int i = 0; i < n; i++) {
            obj[i] = new NnumberInstance();
        }
        return obj;

    }
}

public class MainJavaClass {

public static NnumberInstance obj[];

    public static void main(String[] args) {

        obj = NnumberInstance.getInstance(5);

        for (NnumberInstance instance : obj) {
            System.out.println("------------------------"+instance.hashCode());
        }

    }

}