/**
   A class that describes the effects of an earthquake.
*/
public class Earthquake
{  
   /**
      Constructs an Earthquake object.
      @param magnitude the magnitude on the Richter scale
   */
   public Earthquake(double magnitude)
   {  
      richter = magnitude;
   }

   /**
      Gets a description of the effect of the earthquake.
      @return the description of the effect
   */
   public String getDescription()
   {
      String r;
      if (richter >= 8.0)
         r = "Most structures fall";
      else if (richter >= 7.0)
         r = "Many buildings destroyed";
      else if (richter >= 6.0)
         r = "Many buildings considerably damaged, some collapse";
      else if (richter >= 4.5)
         r = "Damage to poorly constructed buildings";
      else if (richter >= 3.5)
         r = "Felt by many people, no destruction";
      else if (richter >= 0)
         r = "Generally not felt by people";
      else
         r = "Negative numbers are not valid";
      return r;
   }

   private double richter;
}

import java.util.Scanner;

/**
   This program prints a description of an earthquake of a given magnitude.
*/
public class EarthquakeRunner
{  
   public static void main(String[] args)
   {  
      Scanner in = new Scanner(System.in);

      System.out.print("Enter a magnitude on the Richter scale: ");
      double magnitude = in.nextDouble();
      Earthquake quake = new Earthquake(magnitude);
      System.out.println(quake.getDescription());
   }
}

Output:

Enter a magnitude on the Richter scale: 7.1 Many buildings destroyed

Enter a magnitude on the Richter scale: 6.5
Many buildings considerably damaged, some collapse