401-11.1
COMP 401, Spring 2008, Class examples1
// 1. Data available directly. Discouraged!
public class Employee
{
public String name;
public double htInch;
}
// Using the Employee class
Employee e1 = new Employee();
e1.name="Joe";
e1.htInch=72.5;
System.out.println(e1.name+" is "+e1.htInch+" inches tall.");
// 2. Data available through reader/writer methods only. Encouraged!
public class Employee
{
private String name;
private double htInch;
// Readers (getters)
public String getName(){return name;}
public double getHtInch() {return htInch;}
// Writers (setters)
public void setName(String n){name=n;}
public void setHtInch(double h) {htInch=h;}
}
// Using the Employee class
Employee e1 = new Employee();
e1.setName("Joe");
e1.setHtInch(72.5);
System.out.println(e1.getName()+" is "+e1.getHtInch()+" inches tall.");
// 3. Add centimeter height. Data available directly. DANGER!
public class Employee
{
public String name;
public double htInch;
public double htCm;
}
// Using the Employee class
Employee e1 = new Employee();
e1.name="Joe";
e1.htInch=72.5;
e1.htCm=e1.htInch * 2.54;
System.out.println(e1.name+" is "+e1.htInch+" inches tall, and "+
e1.htCm+" cm tall.");
// Allows inconsistency!
e1.htInch=72.5;
e1.htCm=50;
// 4. Avoid inconsistency by making data private and using reader and
1 Many of the course documentation standards are violated in these examples (e.g. no comments; multiple
statements on a line). This is to save paper. Remember, when in doubt, do as I say, not as I do.
