How to return enum value by 2 parameters in java

Question

I have such enum class in java

    public enum MockTypes
    {
        // Atlantis mocks
        ATLANTIS_VERIFY("ATLANTIS", "verify"),
        ATLANTIS_CREATE_RECORD("ATLANTIS", "createRecord"),

    ...

        private String m_adaptor;

        private String m_step;

private MockTypes( String adaptor, String step)
    {
        m_adaptor = adaptor;
        m_step = step;
    }

             public String getAdaptor()
        {
            return m_adaptor;
        }

        public String getStep()
        {
            return m_step;
        }

I have to implement method that returns enum value by adaptor and step parameter.

public MockTypes getMockTypeByName(String adaptor, String step)

but I have no idea how. Could someone help me?

Answer 1

public MockTypes getMockTypeByName(String adaptor, String step)
{
    for(MockTypes m : MockTypes.values())
    {
        if(m.getAdaptor().equals(adaptor) && 
           m.getStep().equals(step)) return m;
    }
    return null;
}

Answer 2

If you want a "constant-time" solution that doesn't involve looking up values, your best option is to initialize a constant Map in a static block in the MockType class.

If you're up for using Guava, it'll actually be relatively pleasant:

public enum MockType {
  ...

  private static final ImmutableTable<String, String, MockType> LOOKUP_TABLE;

  static {
    ImmutableTable.Builder<String, String, MockType> builder =
      ImmutableTable.builder();
    for (MockType mockType : MockType.values()) {
      builder.put(mockType.getAdaptor(), mockType.getStep(), mockType);
    }
    LOOKUP_TABLE = builder.build();
  }

  public static MockType getMockType(String adaptor, String step) {
    return LOOKUP_TABLE.get(adaptor, step);
  }
}

(Disclosure: I contribute to Guava.)

The alternative is going to be relatively similar -- construct a Map<String, Map<String, LookupType>> in a static block, and do lookups from there -- though it's going to require somewhat more work.