errors

if I try exception handling

 Exception in thread "main" java.lang.VerifyError: (class: mirah/MString, method: to_i signature: ()I) Mismatched stack types
	at Usage.main(usage.mirah:2)


if I dont use exception



 java Usage
20
Exception in thread "main" java.lang.NumberFormatException: For input string: "20.5"
	at java.lang.NumberFormatException.forInputString(NumberFormatException.java:48)
	at java.lang.Integer.parseInt(Integer.java:458)
	at java.lang.Integer.parseInt(Integer.java:499)
	at mirah.MString.to_i(mirah.mirah:21)
	at Usage.main(usage.mirah:9)

mirah.mirah

package mirah

import java.lang.Integer
import java.lang.Float

class MString

def to_i():int
 begin
   Integer.parseInt( @s)
 rescue NumberFormatException => e
   puts e.toString
 #ensure
   #puts @s
   #puts "cant be converted to integer"
   #throws NumberFormatException
 end
end

end

usage.mirah

import mirah.MString


sint = MString.new("20")
sfloat=MString.new("20.5")
puts sint.to_i
puts sfloat.to_i