Chapter 4 - Defining Data

Summary

OBJECTIVES

In this chapter you will study:

• Defining Java data;

• Java data types;

• Variable scope;

• Using literals;

• Defining constants;

• Changing data types; and

• Using Java's String class.

In this chapter you will learn how to define data using Java. We will write data definition statements for alphanumeric, numeric, and boolean data (arrays are described and illustrated in Chapter 8). You will also see how to use a supplied Java class named String to simplify the definition and manipulation of alphanumeric data. You will also learn about the scope of variables. Scope determines which parts of your program can access a variable or method.

At the end of the chapter we will develop the complete data definition statements for the attributes of the Community National Bank classes developed in the previous chapter.

NOTES

1. COBOL uses the term data item or field.

2. Java uses the term variable.

3. In keeping with the spirit of Java, here we will use variable.

This chapter assumes you know about:

COBOL

Data division code

Picture clauses

Usage clause

Bits and bytes

Java

Object-oriented concepts (Chapter 2)

Java program structure (Chapter 3)

COBOL PICTURE CLAUSE

Those of us who write COBOL programs are accustomed to using the PICTURE clause to describe data items.