MyObjects.java

package modern.challenge;

import java.util.function.Supplier;

public final class MyObjects {

    private MyObjects() {
        throw new AssertionError("Cannot be instantiated");
    }

    public static <T> T requireNonNullElseThrowIAE(T obj, String message) {

        if (obj == null) {
            throw new IllegalArgumentException(message);
        }

        return obj;
    }

    public static <T> T requireNonNullElseThrowIAE(T obj,
            Supplier<String> messageSupplier) {

        if (obj == null) {
            throw new IllegalArgumentException(messageSupplier == null
                    ? null : messageSupplier.get());
        }

        return obj;
    }

    public static <T, X extends Throwable> T requireNonNullElseThrow(T obj,
            X exception) throws X {

        if (obj == null) {
            throw exception;
        }

        return obj;
    }

    public static <T, X extends Throwable> T requireNotNullElseThrow(T obj,
            Supplier<? extends X> exceptionSupplier) throws X {

        if (obj != null) {
            return obj;
        } else {
            throw exceptionSupplier.get();
        }
    }

}