Hey All,
I have a problem wz the homework of lab 1016 (Collections Framework)
It throws exceptions when i create a TreeSet and LinkedHashSet from the array
of diffrent abject types(Integer, String,object of MyOwnClass ) bec. TreeSet
and LinkedHashSet sorts the elements inside them so when trying to do so, they
cant compare diffrent objects(integer and String forexample)!!!
thats how i understood the problem and it may be wrong...
So, here is the exception it throws:
Me
1
2
[EMAIL PROTECTED]
3
You
[EMAIL PROTECTED]
Exception in thread "main" java.lang.ClassCastException:
mycollectionproject.MyOwnClass cannot be cast to java.lang.Comparable
at java.util.TreeMap.put(TreeMap.java:542)
at java.util.TreeSet.add(TreeSet.java:238)
at mycollectionproject.UtilityClass.Display(UtilityClass.java:18)
at mycollectionproject.Main.main(Main.java:58)
Java Result: 1
As Shown it works well with just the HashSet then throws the exceptions..
And Thats also the code if u wanna check it:
-----------------------------------------------------------------------------------
UtilityClass
--------------------------------------------------------------------------------
package mycollectionproject;
import java.util.Set;
import java.util.Iterator;
public class UtilityClass {
public static void Display(Set s, Object[] objects){
for (int i = 0 ; i < objects.length ; i++){
s.add(objects[i]);
}
for(Iterator it = s.iterator();it.hasNext();){
System.out.println(it.next());
}
}
}
--------------------------------------------------------
the Main
------------------------------------------------
package mycollectionproject;
import java.util.HashSet;
import java.util.Set;
import java.util.TreeSet;
import java.util.Iterator;
import java.util.LinkedHashSet;
class MyOwnClass{
String name = " ";
int age = 0;
public MyOwnClass(String name,int age){
this.name = name;
this.age = age;
}
}
public class Main {
public static void main(String[] args) {
// Create HashSet Object
String me = new String ("Me");
String u = new String("You");
MyOwnClass o1 = new MyOwnClass("Heba",21);
MyOwnClass o2 = new MyOwnClass("Mostafa",18);
Integer one = new Integer(1);
Integer two = new Integer(2);
Integer three = new Integer(3);
Object objects[] = {
me,
u,
o1,
o2,
one,
two,
three
};
Set s = new HashSet();
UtilityClass.Display(s,objects);
s = new TreeSet();
UtilityClass.Display(s,objects);
s = new LinkedHashSet();
UtilityClass.Display(s,objects);
}
}
So, how can i solve this????
Any Help would be Appreciated
Thanks in advance,
Heba
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