class - What is causing the "Exception in thread "main" java.lang.NullPointerException" Error? -

this question has answer here:

• what nullpointerexception, , how fix it? 12 answers

so in middle of project , supposedly code fine part keep getting errors anyway. i'm not sure original problem i'm sure it's changed @ point during changes. despite pointing the line problem, can't figure out problem(s) is/are. causing error?

exception in thread "main" java.lang.nullpointerexception      @ cafe.setname(cafe.java:14)      @ cubancafe.main(cubancafe.java:16)    import java.util.scanner;  public class cubancafe {  public static void main(string[] args) {     string statename;      scanner scan =  new scanner(system.in);      system.out.print(" enter state: ");     statename = scan.nextline();      cafe cafestate = new cafe(statename);     cafestate.setname();     cafestate.settaxrate();     system.out.println(cafestate);;     system.out.println(cafestate.gettaxrate());   } }   public class cafe {     private string state, name;     private double taxrate;      public cafe(string state){         state = state.touppercase( );            name = null;         taxrate = 0;      }      public void setname(){         if(state.equals("md"))              name = "parkville cuban cafe";         else if(state.equals("va"))              name = "alexandria cuban cafe";         else               name = null;     }         public void settaxrate(){         if (state.equals("md"))             taxrate = .06;         else if (state.equals("va"))             taxrate = .04;         else             taxrate = 0;     }      public double gettaxrate(){         return taxrate;      }      public string tostring(){          return (name);     }  } 

the problem here:

state = state.touppercase( );    

the variable state shadowing field state. can solve adding "this":

this.state = state.touppercase( );