Throw exception if value is not found

Question

I want to create ENUM which maps different statuses:

public enum BusinessCustomersStatus {
    A("active"),
    O("onboarding"),
    NV("not_verified"),
        
    private String status;

    BusinessCustomersStatus(String status)
    {
        this.status = status;
    }

    public String getStatus() {
        return status;
    }

    public static BusinessCustomersStatus getStatusByText(String statusText) {
        BusinessCustomersStatus response = null;
        for (BusinessCustomersStatus status : values()) {
            if (status.getStatus().equalsIgnoreCase(statusText)) {
                response = status;
                break;
            }
        }
        if(response == null)
        {
            throw new UnsupportedOperationException(String.format("Unknown status: '%s'", statusText));
        }
        return response;
    }
}

I want to improve the Java method getStatusByText. The code is working but I want to improve the logic for throwing exception.

Answer 1

Few suggestions:

• Naming: A, O, and NV are not clear names. Would be better to use their extended names: ACTIVE, ONBOARDING, and NOT_VERIFIED.
• Missing semicolon: NV("not_verified"), should be NV("not_verified");.
• return instead of break as @dariosicily suggested.

Alternative using Streams:

public static BusinessCustomersStatus getStatusByText(String text) {
        return Stream.of(BusinessCustomersStatus.values())
            .filter(bcs -> bcs.getStatus().equalsIgnoreCase(text))
            .findAny()
            .orElseThrow(() -> new UnsupportedOperationException(String.format("Unknown status: '%s'", text)));
}

Answer 2

About the for in your getStatusByText method :

BusinessCustomersStatus response = null;
for (BusinessCustomersStatus status : values()) {
    if (status.getStatus().equalsIgnoreCase(statusText)) {
       response = status;
       break;
    }
}
if(response == null) {
  throw new UnsupportedOperationException(String.format("Unknown status: '%s'", statusText));
}
return response;

You can return directly the status as your response instead of breaking the for loop and after return the response. This implies the rewritting of your method like below :

public static BusinessCustomersStatus getStatusByText(String statusText) {
    for (BusinessCustomersStatus status : values()) {
        if (status.getStatus().equalsIgnoreCase(statusText)) {
            return status;
        }
    }

    throw new UnsupportedOperationException(String.format("Unknown status: '%s'", statusText));

}

The final part of your method changes too ending directly with the exception in case no value in your for loop satisfies your condition.

Answer 3

Your code can be simpler if you take advantage of valueOf() (see javadoc):

public static BusinessCustomersStatus getStatusByText(String text) {
     return Enum.valueOf(
              BusinessCustomersStatus.class, 
              text.toUpperCase());
}

Note that this throws an IllegalArgumentException if the text does not correspond to a BusinessCustomersStatus value - which actually looks better to me than an UnsupportedOperationException, which is better used when the operation you are attempting (string-to-enum-value) is optional and, in this specific class, not implemented for any argument at all -- and not just "unsupported" for the argument you have just entered.

Answer 4

The previous answers by dariosicily and marc cover most of the ground. But I have a few other comments.

• If you go for more meaningful names for your enum values, you probably don't need a "status" field - you can simply map the name to lower case.
• I'm not sure UnsupportedOperationException is the best choice here, and can see no good reason not to create your own Exception for the purpose.
• If your list of enum values grows significantly bigger, I'd suggest maintaining a Map of the values rather than doing a sequential search. My example below does this, just to illustrate how I'd do that, though for three values it's probably overkill.

package codeReview;

import java.util.Arrays;

import java.util.HashMap;

import java.util.Map;

import codeReview.Penzov.BusinessCustomersStatus.NoSuchStatusException;

public class Penzov {

    public enum BusinessCustomersStatus {
        ACTIVE, //
        ONBOARDING, //
        NOT_VERIFIED;

        static Map <String,BusinessCustomersStatus> statusLookup = new HashMap<>();
        static {
            for (BusinessCustomersStatus status: values()) {
                statusLookup.put(status.getStatus(), status);
            }
        }

        public String getStatus() {
            return name().toLowerCase();
        }

        public static BusinessCustomersStatus getStatusByText(String statusText) throws NoSuchStatusException {
            BusinessCustomersStatus status = statusLookup.get(statusText.toLowerCase());
            if (status != null) {
                return status;
            }

            // Didn't find a match
            throw new NoSuchStatusException(String.format("Unknown status: '%s'", statusText));
        }

        public static class NoSuchStatusException extends Exception {

            private static final long serialVersionUID = -2003653625428537073L;

            public NoSuchStatusException(String message) {
                super(message);
            }
        }
    }

    public static void main(String[] args) {
        for (String testString: Arrays.asList("active", "ONBOARDING", "NoT_VERified", "dubious")) {
            try {
                System.out.format("testString = '%s', status found = '%s'%n", testString, BusinessCustomersStatus.getStatusByText(testString));
            } catch (NoSuchStatusException e) {
                System.out.format("testString = '%s', exception thrown = '%s'%n", testString, String.valueOf(e));
            }
        }
    }
}