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Comaparator Program error !!!

Submitted by javalearner on Tue, 12/20/2011 - 13:41

Java

i am a beginner of java , i was trying to use comaparator for tree set to get reverse order sort for the following program but was getting error like ComparatorDemo.java uses unchecked or unsafe operations Recompile with -xlint : unchecked for details.

import java.util.*;
class MyComp implements Comparator

{
   public int compare(Object a , Object b)
   {
        String astr,bstr;
        astr = (String)a;
        bstr = (String)b;
        return bstr.compareTo(astr);
   }
}
public class ComparatorDemo
{
   public static void main(String args[])
   {
        TreeSet<String> ts = new TreeSet<String>(new MyComp());
        ts.add("D");
        ts.add("A");
        ts.add("O");
        ts.add("S");
        ts.add("N");
        ts.add("C");
        ts.add("B");
        Iterator i = ts.iterator();
        while(i.hasNext())
        {
            Object e = i.next();
            System.out.println(e+ " ");
        }
        System.out.println();
   }
}

can any1 please help me out regarding the issue.....

1 answer

Re: Comaparator Program error !!!

Wed, 03/14/2012 - 14:45 — ravishnkr.m

Hi the above code is working without errors. below is the few changes i made related to MyComp w.r.to Generics.

import java.util.Comparator;

class MyComp implements Comparator<String>

{
public int compare(String a , String b)
{
String astr,bstr;
astr = (String)a;
bstr = (String)b;
return bstr.compareTo(astr);
}
}

import java.util.Iterator;
import java.util.TreeSet;

public class ComparatorDemo {
public static void main(String args[])
{
TreeSet<String> ts = new TreeSet<String>(new MyComp());
ts.add("D");
ts.add("A");
ts.add("O");
ts.add("S");
ts.add("N");
ts.add("C");
ts.add("B");
Iterator i = ts.iterator();
while(i.hasNext())
{
Object e = i.next();
System.out.println(e+ " ");
}
System.out.println();
}
}