Java: get the public static final constant variable name by its value

We can solve this problem with reflections. Below snippet return the name of a public static final constant defined in a class or an interface by its value.

 

 

Find the below working application.

 

AppConfigs.java

package com.sample.app.constants;

public interface AppConfigs {
	public static final String APP_VERSION = "1.23";
	public static final Integer FIRST_RELEASE_YEAR = 2019;

}

GetConstantNameByValue.java

package com.sample.app;

import java.lang.reflect.Field;
import java.lang.reflect.Modifier;

import com.sample.app.constants.AppConfigs;

public class GetConstantNameByValue {

	public static String getConstantName(Class<?> clazz, Object value)
			throws IllegalArgumentException, IllegalAccessException {
		for (Field field : clazz.getDeclaredFields()) {

			// Get the field modifier constant
			int modifierConstant = field.getModifiers();

			if (Modifier.isStatic(modifierConstant) && Modifier.isPublic(modifierConstant)
					&& Modifier.isFinal(modifierConstant)) {

				if (field.get(null).equals(value)) {
					return field.getName();
				}

			}
		}

		throw new IllegalArgumentException("value not found or it is not a public static final");
	}

	public static void main(String[] args) throws IllegalArgumentException, IllegalAccessException {
		String constantName = getConstantName(AppConfigs.class, 2019);
		System.out.println(constantName);

		constantName = getConstantName(AppConfigs.class, "1.23");
		System.out.println(constantName);

	}

}

Output

FIRST_RELEASE_YEAR
APP_VERSION

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