Console based command processing: Mapping string to enum in java

For my java console application, I need to call a set of functions with user given arguments. My operations O1, O2, .. O5 are defined as an enum as

enum Operations {O1, O2, O3, O4, O5};

I need to read user input args[0] and call function F1, F2,...F5.

For example user is going to give:

>java MyApp O1 5 6

For this I suppose I need to map sting (args[0]) to an enum so that I can use switch select. How to do this?

From stackoverflow

• Enum.valueOf(Class, String).

  Example

  Operations oper = Enum.valueOf(Operations.class, args[0]);
  

  Will throw an exception if there are no enum values that matches args[0]

• I suppose using what chuk lee 's lead you can come up with pritty cool program here what I did.

  public class Main {
  
  
  public static void main(String[] args) {
  
      if(args.length < NUMBER_OF_OPERATORS){
           throw new IllegalArgumentException(INSUFFICIENT_OPERANDS); 
      }
  
      Operator operator = Enum.valueOf(Operator.class,
                                           args[OPERATION_NAME].toUpperCase());
  
      System.out.println(operator.operate(args[FIRST_OPERAND],
                                                     args[SECOND_OPERAND]));
  
  
  }
  
  
  private enum Operator {
  
      ADD,SUBSTRACT,MULTIPLY,DIVIDE;
  
      public String operate(String aString, String bString) {
  
          int a = Integer.valueOf(aString);
          int b = Integer.valueOf(bString);
  
          int out = 0;
  
  
          switch(this) {
  
  
              case ADD    : out = a + b; break;
              case SUBSTRACT  : out = a - b; break;
              case MULTIPLY   : out = a * b; break;
              case DIVIDE : out = a / b; break;
              default: throw new UnsupportedOperationException();
          }
  
          return String.valueOf(out);
      }
  
  }
  
  private static final int NUMBER_OF_OPERATORS = 3;
  private static final int OPERATION_NAME = 0;
  private static final int FIRST_OPERAND = 1;
  private static final int SECOND_OPERAND = 2;
  private static final String INSUFFICIENT_OPERANDS = 
                             "Insufficient operads to carry out the operation.";
  

  }