Re: My set fails

Could anyone tell me why? How do I fix it?

package setTest;
import java.util.*;

public class SetTest implements Comparable<SetTest> {
   public String toString(){
       return this.s1 + " " + this.x1;
   }
   public static void display(){
       for(SetTest s : set){
           System.out.println(s);
       }
   }
   public static void populate(){
       for (int i = 1; i < 3; i++){
           set.add(new SetTest(1, "One"));
           set.add(new SetTest(2, "One"));
           set.add(new SetTest(1, "Two"));
       }
   }
   public String getX1(){
       return x1;
   }
   public int getS1(){
       return s1;
   }

   public boolean equals(Object o) {
       if (!(o instanceof SetTest))
           return false;
       SetTest s = (SetTest)o;
       if(s.getS1() == this.getS1() && s.getX1() == this.getX1())
           return true;
       else
           return false;
   }
   public int compareTo(SetTest s){
       if(this == s)
           return 1;
       else
           return -1;
   }

   public SetTest(int s, String x){
       s1 = s;
       x1 = x;
   }
   public static void main(String[] args){
       populate();
       System.out.println("The size of set is: " + set.size());

       display();
   }
   private int s1;
   private String x1;
   static protected Set<SetTest> set = new TreeSet<SetTest>();
}