Question

I am trying to initialise the array C in the loop, but it gives error :
C is array of class ipdata and I have declared it and trying to initialise it inside the loop.

import java.io.*;
import java.util.*;
public class cluster_anlysis {
    class ipdata{


        float a,b;
        int cluster;

        ipdata()
        {
            a=0;
        }
    }
    public float modc(float a){
            if(a<0.0)
                a=-a;
            return a;
    }
    public static void main(String[] args) {
        cluster_anlysis obj=new cluster_anlysis();
    ipdata C[] = new ipdata[50];
    float mean1,mean2,mean3;
    int i,j,n1=0,n2=0,n3=0,flag=0;
    float ina=0.0f;
    float inb=0.0f;

    //BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
    Scanner scan =new Scanner(System.in);
    System.out.println("pls enter no of data: ");
    Integer no = scan.nextInt();
    System.out.println("\nnow enter the x and y values");
    for(i=0;i<no;i++)
    {
        ina=scan.nextFloat();
        inb=scan.nextFloat();
        System.out.println(ina);
        C[i]= new ipdata();          // this line is giving error

        C[i].a=ina;
        C[i].b=inb;
        C[i].cluster=0;
    }


    }

}

What could be the problem ?
it says :
No enclosing instance of type cluster_anlysis is accessible. Must qualify the allocation with an enclosing instance of type cluster_anlysis (e.g. x.new A() where x is an instance of cluster_anlysis).

Answer 1

you create an instance of inner class from static methods of your outer class using the outer class instance.

c[i]= new cluster_anlysis().new ipdata();

as you have alread created cluster_anlysis instance in your first line of main method.

cluster_anlysis obj = new Cluster_anlysis();

you could simple do.

c[i]= obj.new ipdata();

read about Inner classes in java

but if you want to create an inner class instance from the non-static methods of your outer class you dont need the instance of your Outer Class .

 public class OuterClass {
       public void method(){
           InnerClass inner = new InnerClass();
       }
       class InnerClass{
         }
    }

and also follow class name convention as posted by @A.R.S and @JB Nizet in their solutions.