An enum-like class with a type parameter and a values() method.

Example.java

import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
import java.util.Arrays;
import java.util.List;
import java.util.function.Supplier;
import java.util.stream.Collectors;

public final class Example<T> {
    public static final Example<Integer> INT = new Example<>(Integer.class, () -> 123);
    public static final Example<String> STR = new Example<>(String.class, () -> "Test");

    private final Class<T> type;
    private final Supplier<T> supplier;

    private Example(Class<T> type, Supplier<T> supplier) {
        this.type = type;
        this.supplier = supplier;
    }

    public Class<T> getType() {
        return type;
    }

    public Supplier<T> getSupplier() {
        return supplier;
    }

    public static List<Example<?>> values() {
        return Arrays.stream(Example.class.getDeclaredFields())
                .filter(Example::isConstant)
                .map(Example::getConstant)
                .collect(Collectors.toList());
    }

    private static boolean isConstant(Field field) {
        int modifiers = field.getModifiers();
        return Modifier.isStatic(modifiers) && Modifier.isFinal(modifiers);
    }

    private static Example<?> getConstant(Field field) {
        try {
            return (Example<?>) field.get(null);
        } catch (IllegalAccessException e) {
            throw new RuntimeException("Cannot access field: " + field.getName(), e);
        }
    }
}