Search an enum by a unique attribute

I was recently defining an enum with some keys. But the enum needed more than a key. It also needed a configuration parameter that would define if this key has some special feature avaliable.

So I defined the enum with a constructor that had 2 inputs, the key and the configuration boolean attribute.

Now the question was, how to find the enum for the key. And here I am going to exactly show the code that does it.

import java.util.HashMap;
import java.util.Map;


public enum MyEnum {
	KEY1 ("key1", false),
	KEY2 ("key2", false);
	

	private final String key;
	private final boolean featureAvailable;
	private static final Map<String, MyEnum> LABEL_MAP = new HashMap<>();
	
	static {
		for (MyEnum enumVal : MyEnum.values()) {
			LABEL_MAP.put(enumVal.getKey(), enumVal);
		}
	}
	
	private MyEnum(String key, boolean featureAvailable) {
		this.key = key;
		this.featureAvailable = featureAvailable;
	}
	

	
	
	public static MyEnum getEnumFromLabel(String label) {
		return LABEL_MAP.get(label);
	}


	public boolean isFeatureAvailable() {
		return featureAvailable;
	}


	public String getKey() {
		return key;
	}
}

Now from the above class you can use getEnumFromLabel to get the enum from the label.

Here is a little better version of the Map. The below code makes sure that the keys are not duplicated. Any duplicate would raise an error.

static {
		for (MyEnum enumVal : MyEnum.values()) {
			if(LABEL_MAP.containsKey(enumVal.getKey())) {
				throw new IllegalStateException("Duplicate Keys for enums: " + enumVal + " : " + LABEL_MAP.get(enumVal.getKey()));
			}
			LABEL_MAP.put(enumVal.getKey(), enumVal);
		}
	}

And here is the test to show, how the above code can help improve the enum implementation

import java.util.HashMap;
import java.util.Map;


public enum MyEnum {
	KEY1 ("key1", false),
	KEY2 ("key2", false),
	KEY3 ("key2", false);
	

	private final String key;
	private final boolean featureAvailable;
	private static final Map<String, MyEnum> LABEL_MAP = new HashMap<>();
	
	static {
		for (MyEnum enumVal : MyEnum.values()) {
			if(LABEL_MAP.containsKey(enumVal.getKey())) {
				throw new IllegalStateException("Duplicate Keys for enums: " + enumVal + " : " + LABEL_MAP.get(enumVal.getKey()));
			}
			LABEL_MAP.put(enumVal.getKey(), enumVal);
		}
	}
	
	private MyEnum(String key, boolean featureAvailable) {
		this.key = key;
		this.featureAvailable = featureAvailable;
	}
	

	
	
	public static MyEnum getEnumFromLabel(String label) {
		return LABEL_MAP.get(label);
	}


	public boolean isFeatureAvailable() {
		return featureAvailable;
	}


	public String getKey() {
		return key;
	}
	
	public static void main(String[] args) {
		for (MyEnum enumVal : MyEnum.values()) {
			System.out.println(enumVal.getKey()	+ " : " +	getEnumFromLabel(enumVal.getKey()));
		}
	}
}

You can run the above code and see that it doesn’t run. It throws an error with duplicate Key.