The problem

Suppose we have a class that can represent two-dimensional shapes:

0260: public class Shape                                             // Shape.java
0261: {
0262:    private int iX, iY;
0263:    public Shape(int pX, int pY)
0264:    {
0265:       iX = pX; iY = pY;
0266:    }
0267:    public int getX()
0268:    {
0269:       return iX;
0270:    }
0271:    public int getY()
0272:    {
0273:       return iY;
0274:    }
0275:    public Shape translate(int pX, int pY)
0276:    {
0277:       return new Shape(iX + pX, iY + pY);
0278:    }
0279:    public boolean equals(Object pObject)
0280:    { 
0281:       return iX==((Shape)pObject).iX && iY==((Shape)pObject).iY;
0282:    }
0283:    public String toString()
0284:    {
0285:       return iX + ":" + iY;
0286:    }
0287: }

You will see that this class has no setXXX methods.
So, when an object of this class has been created, it cannot then be changed.
The objects of this class are said to be immutable.
However, the class does provide a method called translate.
When applied to some Shape, it produces a new Shape that is (pX,pY) away from the first Shape:
```
Shape tShape = new Shape(100, 200);
Shape tNewShape = tShape.translate(1, 2);
System.out.println(tNewShape);
```