I was running some rightsizing tests and had to blast random objects of my various class types. Here is the code I came up with.

private static <T> T random(Class<?> recordClass) {

    Constructor<?>[] constructors = recordClass.getConstructors();
    Constructor<?> maxParamConstructor = constructors[0];

    for (Constructor<?> check : constructors) {
        if (check.getParameterCount() > maxParamConstructor.getParameterCount())
            maxParamConstructor = check;

    if (maxParamConstructor.getParameterCount() > 0) {

        Type[] types = maxParamConstructor.getGenericParameterTypes();
        Object[] params = new Object[types.length];

        for (int index = 0; index < types.length; index++) {
            params[index] = getRandom(types[index].getTypeName());

        return (T) maxParamConstructor.newInstance(params);
    } else
        return (T) recordClass.newInstance();

private static Object getRandom(String type) {

    switch (type) {

        //TODO add others
        case "java.lang.Long":
            return ThreadLocalRandom.current().nextLong();
        case "java.lang.Boolean":
            return ThreadLocalRandom.current().nextBoolean();
        case "java.lang.String":
            return UUID.randomUUID().toString();
        case "java.lang.CharSequence":
            return UUID.randomUUID().toString();
        case "java.lang.Double":
            return ThreadLocalRandom.current().nextDouble();

            return random(Class.forName(type));

Was wondering if it would give me trouble during my tests. Is it any good ? thanks.

  • 1
    \$\begingroup\$ I try to avoid randomness in tests because you are then testing different conditions every time you run the test. Did the test fail because I changed the code or because it was testing some new combination of random objects? There's no way to know. \$\endgroup\$
    – Michael
    Jan 6 '17 at 15:01
  • \$\begingroup\$ well this does make sense, thanks for your input :) I also noticed my compressions would get screwed this way \$\endgroup\$
    – Dexter
    Jan 8 '17 at 11:18

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