public    interface Icolor{               int apply(int x,int y);    }     public enum color implements Icolor{          plus("+"){                 public int apply(int x,int y){ return x+y;}     },     min("-"){                 public int apply(int x,int y){ return x-y;}     }          ;                    private final String num;          color(String num){              this.num=num;          }         } //调用 color.plus.apply(100, 1)