Fill primitive properties with random data automatically? [closed]

Is there a java library that would help with creating instances of classes for testing? One that examines the properties of a bean and fills it with random data.
I'm basically looking for Java equivalent of Object Hydrator for C#.

You could use PoDaM:

PodamFactory factory = new PodamFactoryImpl();
Pojo myPojo = factory.manufacturePojo(Pojo.class);

Take a look at Easy Random.

It allows you to populate a Java Object graph with random data.

Hope it helps.

I don't know of a framework, but it's pretty simple to write one of those yourself. The complexity comes in non-simple properties, aka object associations. Something like this handles the basics and then some:

public static void randomlyPopulateFields(Object object) {
    new RandomValueFieldPopulator().populate(object);
}

public static class RandomValueFieldPopulator {
    public void populate(Object object) {
        ReflectionUtils.doWithFields(object.getClass(), new RandomValueFieldSetterCallback(object));
    }

    private static class RandomValueFieldSetterCallback implements FieldCallback {
        private Object targetObject;

        public RandomValueFieldSetterCallback(Object targetObject) {
            this.targetObject = targetObject;
        }

        @Override
        public void doWith(Field field) throws IllegalAccessException {
            Class<?> fieldType = field.getType();
            if (!Modifier.isFinal(field.getModifiers())) {
                Object value = generateRandomValue(fieldType, new WarnOnCantGenerateValueHandler(field));
                if (!value.equals(UNGENERATED_VALUE_MARKER)) {
                    ReflectionUtils.makeAccessible(field);
                    field.set(targetObject, value);
                }
            }
        }
    }
}

public static Object generateRandomValue(Class<?> fieldType, CantGenerateValueHandler cantGenerateValueHandler) {
    if (fieldType.equals(String.class)) {
        return UUID.randomUUID().toString();
    } else if (Date.class.isAssignableFrom(fieldType)) {
        return new Date(System.currentTimeMillis() - random.nextInt(DATE_WINDOW_MILLIS));
    } else if (Number.class.isAssignableFrom(fieldType)) {
        return random.nextInt(Byte.MAX_VALUE) + 1;
    } else if (fieldType.equals(Integer.TYPE)) {
        return random.nextInt();
    } else if (fieldType.equals(Long.TYPE)) {
        return random.nextInt();
    } else if (Enum.class.isAssignableFrom(fieldType)) {
        Object[] enumValues = fieldType.getEnumConstants();
        return enumValues[random.nextInt(enumValues.length)];
    } else {
        return cantGenerateValueHandler.handle();
    }
}

https://github.com/benas/random-beans did the work for me, while PoDam failed with "fluent" setters and answer by Ryan Stewart is not complete for copy-paste as has references to classes that are not exposed! With random-beans it's as easy as:

Auction auction = EnhancedRandom.random(Auction.class);

Gradle:

testCompile ('io.github.benas:random-beans:3.4.0')