Xponents | Geographic Place , Date/time , and Pattern entity | Natural Language Processing library

xponents.java:66: error: invalid method declaration; return type required
public Exponent(int num, int exponent, int x)

  public class Exponents implements Comparable
{
   private int num;
   private int exponent;
   private int x;

   public Exponents(int num, int exponent, int x)
   {
      this.num = num;
      this.exponent = exponent;
      this.x = x;
   }
   public int Answer()
   {
      int x = Math.pow(num,exponent);
      return x;
   }

    public String toString()
   {
      String s = ("Exponent: " + exponent + "\n Number: "+ num + "\nYour x is: )" + x);
      return s;
   }
   public int compareTo(Answer e)
   {
      return this.x - o.x;
   }
}

Exponents.java:83: error: cannot find symbol
   public int compareTo(Answer e)
                    ^
  symbol:   class Answer
  location: class Exponents



Exponents.java:74: error: incompatible types: possible lossy conversion from double to int
      int x = Math.pow(num,exponent);


                  ^
Exponents.java:85: error: cannot find symbol
      return this.x - o.x;
                  ^
  symbol:   variable o
  location: class Exponents
3 errors