java.lang.NumberFormatException: For input string: ""

java.lang.NumberFormatException: For input string: ""
	at java.lang.NumberFormatException.forInputString(NumberFormatException.java:48)
	at java.lang.Integer.parseInt(Integer.java:468)
	at java.lang.Integer.(Integer.java:620)
	at es.iris.servlets.Partes.accionParteLesionados(Partes.java:145)
	at es.iris.servlets.Partes.accion(Partes.java:73)
	at es.iris.servlets.Partes.responderPeticion(Partes.java:58)
	at es.iris.servlets.Partes.doGet(Partes.java:45)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:715)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:840)
	at com.mortbay.HTTP.Handler.ServletHolder.service(ServletHolder.java:510)
	at com.mortbay.HTTP.Handler.ServletHandler.handle(ServletHandler.java:184)
	at com.mortbay.HTTP.HttpServer.handle(HttpServer.java:361)
	at com.mortbay.HTTP.HttpListener.handleConnection(HttpListener.java:146)
	at com.mortbay.Util.ThreadedServer.run(ThreadedServer.java:589)
	at java.lang.Thread.run(Thread.java:595)