write a java program to short the names in alphabets order?

Answer 1

First, I'm assuming the names are all String objects.

You can store them in an array and then sort them with the java.util.Arrays.sort() method. You could also put them in a Collection implementation (such as ArrayList) and then use the Collections.sort() method. Both of these approaches won't deal with case-insensitive order, though. Those beginning with uppercase will appear before all those beginning with lower case. To handle this "special" sorting need, you need to provide a Comparator implementation.

Here is an example Comparator:

class CaseInsensitiveStringComparator implements java.util.Comparator{

/**
* Compares two String objects in a case-insensitive
* natural order.
* @param o1
* @param o2
* @return
* @see
*/
public int compare(Object o1, Object o2) {
String a = (String)o1;
String b = (String)o2;
int retVal = a.compareToIgnoreCase(b);
return retVal;
}

}

Both the Arrays and Collections classes have sort methods that take an additional Comparator parameter.

For example, here is a little snippet that uses the Comparator described above:

String a = "a";
String A = "A";
String b = "b";
String B = "B";
ArrayList list = new ArrayList();
list.add(b);
list.add(A);
list.add(B);
list.add(a);

Collections.sort(list, new CaseInsensitiveStringComparator());
System.out.println(list);

Using the above code results in output of
[A, a, B, b]
Using Collections.sort(list) would have resulted in output of
[A, B, a, b]

Answer 2

Just put the names in a list and call the sort method.

Answer 3

use java.util package in that

go through this link
http://java.sun.com/j2se/1.4.2/docs/api/java/util/TreeSet.html