class cast exception

[nitin sharma]

class fruit
{
public void popo1()
{
System.out.println("this is a popo1 of the fruit class");
}
}
interface squeezable
{
}
class citrus extends fruit implements squeezable
{
public void nitin()
{
System.out.println("what the hell is going on");
}
}
class lemon extends citrus
{
}
class grapefruit extends citrus
{
public void nitin()
{
System.out.println("what r u trying to do");
}
}
class lapore
{
public static void main(String[]args)
{
grapefruit g[]=new grapefruit[50];
for(int i=0;i<g.length;i++)>
{
g[i]=new grapefruit();
}
citrus[] s=g;
for(int i=0;i<s.length;i++)>
{
s[i].nitin();
}
squeezable[] d=s;
lemon n[]=(lemon[])d; //line number 45.
}
}
hi everybody,
i am getting a classcast exception in line number 45.Please throw some light on it.

[Cindy Glass]

g is an array of grapefruits. Then you created s and put g in it. It is still an array of grapefruits just in a citrus variable. Then you put s in a squeezable array d. It is still an array of grapefruits but now in a squeezeable variable.
Then you tried to cast the grapefruit array in d into a lemon. No, No, NO.

[huiying li]

Both lemon and grapefruit class extends citrus, so their peer classes and can not be casted to each other.