Hi Pavan Kundagol,
I thank you for your suggestion.
I exchange the (key, value) parameters in put() method and it works. i
understand why it is a ClassCastException, because I did like that for "m"
object :
Map m = new HashMap();
m.put(new String("Bako"), 1);
m.put(new String("Takumah"), 2);
MyOwnClass house = new MyOwnClass();
house.setHeight(7.5);
m.put(house.getHeight(), 3);
MyOwnClass truck = new MyOwnClass();
truck.setHeight(6.7);
m.put(truck.getHeight(), 4);
m.put(new Integer(145), 5);
Map tm = new TreeMap();
tm.putAll(m);
And I think there was a problem with the type Integer and String in the map.
And now, it works well.
Thanks.
Bako
________________________________
From: pavan kumar <[email protected]>
To: [email protected]
Sent: Tuesday, April 21, 2009 3:17:06 AM
Subject: [java programming] Re: Lab 1016 : 3.1 build and run a simple
application that uses HashMap
Hi,
This is my first time using java passions...so something is wrong please
teach me...
public class treemap {
public static void main(String[] args) {
Map m = new HashMap();
m.put(4, "four");
m.put(1, "one");
m.put(3, "three");
m.put(2, "two");
printMap(m);
Map tm = new TreeMap();
tm.putAll(m);
printMap(tm);
}
private static void printMap(Map m) {
System.err.println("priniting map:"+m);
for (Iterator it = m.values().iterator(); it.hasNext();) {
System.err.println(it.next());
}
System.err.println("----------------");
}
}
output:
priniting map:{1=one, 2=two, 3=three, 4=four}
one
two
three
four
----------------
priniting map:{1=one, 2=two, 3=three, 4=four}
one
two
three
four
----------------
so what is ur problem....
tm.putAll(m); //what is 'm' object...
On Tue, Apr 21, 2009 at 2:34 AM, Bakoly Takumah <[email protected]> wrote:
Hi everyone,
In the lab 1016, 3.1 build and run a simple application that uses HashMap, and
part 4 of this segment advise us to do our own exercise : please do the
following .... display them in both unsorted and sorted order.
I did the unsorted order and it goes well, but I have a problem with the
unsorted order, I got an execption : java.lang.ClassCastException.
I use putAll() method like that :
Map tm = new TreeMap();
tm.putAll(m);
And then display tm.
I have looked at the JavaDoc about this exception for putAll but I don't really
understand what it means :
ClassCastException - if the class of a key or value in the specified map
prevents it from being stored in this map
Please, help.
Thanks in advance.
Bako
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