Question about Java class

Question

I am just learning Java as a hobby.

How do I make a class define a field? E.g.

private string[] biscuitlist

Thank you for any help provided.

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Answer 1

Java is case sensitive. You need to declare it as String[], not as string[].

package yourpackage;
public class YourClass {
 private String[] biscuitlist;
}

That said, this is actually not "subclassing". So your question title actually contradicts with the question message. To learn more about Java in general, I strongly recommend to go through the Trails Covering the Basics. Good luck.

• user267926: the link you gave seems to be a rather good resource many thanks for your help
• BalusC: Sure, when you want to learn X, start with the documentation/tutorials/guides which are provided with X. In case of Sun Java, that are the Sun tutorials :) Good luck and happy coding!
• George Profenza: a bit off topic...the Trails Covering the Basics page makes my eyes hurt.Am I the only one...full red, full blue, busy page. JavaDocs formatting is a lot better :)

Answer 2

The declaration goes inside the class definition as well.

public class SomeClass {
 private String[] biscuitlist; // declare the variable
 public SomeClass(){} // empty constructor
 public String[] getList() {
 // the variable is private so provide a getter for external access
 return biscuitList; 
 }
}

If you declare the variable private only methods inside the class can access it. Checkout access controls to understand this if you need to.

Answer 3

You have defined variable already. Just note,

1. Java is case sensitive.
2. All classes starts uppercase, e.g. String, Date, List, etc by convention.

Answer 4

A class is basically a set of data (fields) and a bunch of operations(methods) on those fields

public class yourClass{
 //define fields here
 private String[] biscuitlist; 
 // java will automagically set biscuitlist to a null reference
 //make a constructor for your class if it will ever be instantiated
 public yourClass(){
 }
 //do stuff here (methods)
}

So basically defining a field is as simple as typing in the access(public, private, protected) giving it a type (String, int, String[], Object) and giving it a name. if not assigned a value after they will default based on the java API (objects get a null reference, ints get 0 etc.)