trublaha
asked on
Sorting an ArrayList of Objects??
I tried to make a program to sort an ArrayList of objects, but can’t get it to work. What am I doing wrong?
import java.util.*;
class test
{
public static void main (String [] args)
{
List list = new ArrayList();
trivialObject testa = new trivialObject ("ABCD", "EFGH");
trivialObject testb = new trivialObject ("AAAA", "BCDA");
list.add (testa);
list.add (testb);
Collections.sort(list);
}
}
class trivialObject
{
String valuea, valueb;
trivialObject(String valuea, String valueb)
{
this.valuea = valuea; this.valueb = valueb;
}
public String toString ()
{
String result = (valuea + ", " + valueb);
return result;
}
}
import java.util.*;
class test
{
public static void main (String [] args)
{
List list = new ArrayList();
trivialObject testa = new trivialObject ("ABCD", "EFGH");
trivialObject testb = new trivialObject ("AAAA", "BCDA");
list.add (testa);
list.add (testb);
Collections.sort(list);
}
}
class trivialObject
{
String valuea, valueb;
trivialObject(String valuea, String valueb)
{
this.valuea = valuea; this.valueb = valueb;
}
public String toString ()
{
String result = (valuea + ", " + valueb);
return result;
}
}
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Sorry, I was incomplete with the comparator. In the second case, you would have to call another method for sorting:
Collections.sort(List list, Comparator c)
Collections.sort(List list, Comparator c)
Comparator c=new Comparator(){
public int compare(Object o1,Object o2){
trivialObject t1=(trivialObject)o1;
trivialObject t2=(trivialObject)o2;
//perform the comparison here
return t1.valuea.compareTo(t2.val
//a silly example again.
}
}