Java

import java.util.ArrayList;
import java.util.Collections;

public class UseofComparableInteface {
    public static void main(String args[])
    {
        ArrayList <Information> alist = new ArrayList<Information>();

1.Why we customize equls() ,hashCode() methods?Please give some realtime examples?
2.Shallwe use ArrayList in Servlet?

equals() method is available to all java collection classes from the object class.this method is also declared in Comparator in

Write a program to generate the patterns:
   * * * * *
             *
          *
       *
   * * * * *

to give example to own split method for using string.

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

{

i have a basic applet written just using init, actionlistener
extends Applet implements ActionListener set up but i keep getting message Applet not initilaised - what's the problem?

I have a text file with this format:

aaa:bbb:ccc
ddd:eee:fff
ggg:hhh:iii

so now i want to search for fff and replace it with kkk but in same file. i know how to do by pasting stuff in other file. but for this i need that to be in same file

any help will be appreciated

Thanks