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

public class SortOnOneValue implements Comparable  {
   int value1;
   int value2;
   public SortOnOneValue(int val1, int val2) {
       value1 = val1;
       value2 = val2;
   }

   public int compareTo(Object obj) {
       SortOnOneValue val = (SortOnOneValue) obj;
       return this.value1 - val.value1;
     }

   public String toString() {
       return "value1 = " + value1 + " value2 = " + value2;
   }

   /**
    * @param args
    */
   public static void main(String[] args) {
       ArrayList myList =new ArrayList();
       myList.add(new SortOnOneValue(1,5));
       myList.add(new SortOnOneValue(5,5));
       myList.add(new SortOnOneValue(2,5));
       System.out.println(myList);
       Collections.sort(myList);
       System.out.println(myList);

   }

}
Dinesh

If the value1 order is the natural order for class a, make it implement
Comparable, and use the Collections sorts for lists of Comparable.

If there are several equally significant orders, create a Comparator for
each order, and use the Collections sorts with Comparator.

Patricia

...

Look up the Comparable and Comparator interfaces.
If you only need to sort on one value make your class implement
Comparable.
If you need to sort on different values at different times, create a
separate Comparator (i.e. a class that implements the Comparator
interface) for each value you are sorting on.