CODEWITHSUNDEEP
javaclassobjectfield
user3757743
user3757743

Reputation: 13

Accessing Fields in a Class in Java

I apologize for the mistakes as this is my first post here. This is a basic question but I do not understand the answers I've seen. In the following Java code:

public class RAPVAR_XDATA_TYPE{

        public class datacfg{
            public int datacfg_len;
            public float datacfg_val;
        }

        public class numdata{
            public int numdata_len;
            public float numdata_val;
        }

        public class strdata{
            public int strdata_len;
            public String strdata_val;
        }
}

Why can I not access numdata_len in the following fashion:

RAPVAR_XDATA_TYPE.numdata.numdata_len = 1;

RAPVAR_XDATA_TYPE rxt = new RAPVAR_XDATA_TYPE();
rxt.numdata.numdata_len = 1;

I am trying to build a data structure to mimic the same structure I did in c++ a while ago.

Upvotes: 1

Views: 74

Answers (2)

LhasaDad
LhasaDad

Reputation: 2153

You need to consider that what you have in a class is a 'pattern' for the the data elements an instance of the class will contain. in your example you also have an inner class which is just a nested 'pattern'. Even if you new the outer class you have not created space for the item in the inner class. you would need a constructor that new-ed (instantiated) the inter class objects and set references to them in the instance of your outer class to have something 'like' what you had in c++.

Upvotes: 0

Hovercraft Full Of Eels
Hovercraft Full Of Eels

Reputation: 285450

You would need to make the inner classes and their fields static for this to work, but before you do this, don't. Don't try to make C++ structures with Java as that's not the Java way, and will lead to poorly constructed Java programs. Instead get a good book on OOP and Java such as "Thinking in Java" and a book on design patterns such as the GoF book or the Head First book, and learn the Java "way".

Upvotes: 1

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