Single file class/program for POC of a Stack Overflow answer

ObjectInputExample.java

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInput;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.ObjectStreamConstants;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
import java.util.Objects;


/**
 * This is a "test" program for testing the method I wrote for a StackOverflow answer here:
 * <p>
 * https://stackoverflow.com/questions/50124409/using-generic-arraylist-as-parameter/50124491#50124491
 * <p>
 * Please forgive the lack of code documentation/Javadoc as this was just a short POC and not intended as production
 * quality code.
 *
 * @author Emily Mabrey <[email protected]>
 */
@SuppressWarnings("UseOfSystemOutOrSystemErr")
public class ObjectInputExample {


    /**
     * For a given file at the specified path, attempts to deserialize and return an Object instance specified via
     * the various generic types.
     * @param type The Class representing the stored Object type within the serialized object graph
     * @param fileName The path of the file to deserialize
     * @param <OUTPUT> The return type expected by the caller
     * @param <INPUT> The type of the object stored within the serialized object graph
     * @return The deserialized object. If it returns null the null was checked for type-safety as far as possible.
     *
     * @throws IOException Means the file IO failed
     * @throws ClassNotFoundException Means the casting of serialized objects failed
     */
    public static <OUTPUT extends Serializable, INPUT extends Serializable>
        OUTPUT getObjectFromFile(Class<INPUT> type, CharSequence fileName)
        throws IOException, ClassNotFoundException {

        final String filenameString = Objects.requireNonNull(fileName).toString();
        final Class<INPUT> inputType = Objects.requireNonNull(type);

        try (ObjectInput ois = new ObjectInputStream(new FileInputStream(filenameString))) {
            final Object rawObject = ois.readObject();

            @SuppressWarnings("unchecked")
            final OUTPUT output = (OUTPUT) (rawObject == null ? null : inputType.cast(rawObject));

            return output;
        }

    }

    /**
     * For a given file at the specified path, attempts to deserialize and add an Object instance specified via
     * the various generic types into the given Collection.
     *
     * @param out The Collection which can accept the deserialized object
     * @param type The Class representing the stored Object type within the serialized object graph
     * @param fileName The path of the file to deserialize
     * @param <DESIRED> The element type for the output Collection
     * @param <STORED> The Object type of the deserialized Object
     * @return A boolean representing successful loading of a serialized Object via true; failure is false.
     *
     * @throws IOException Means the file IO failed
     * @throws ClassNotFoundException Means the casting of serialized objects failed
     */
    public static <DESIRED extends Serializable, STORED extends Serializable>
        boolean addArrayListFromFile(Collection<DESIRED> out, Class<STORED> type, CharSequence fileName)
        throws IOException, ClassNotFoundException {

        @SuppressWarnings("unchecked")
        final ArrayList<DESIRED> inList = getObjectFromFile(type, fileName);

        return inList != null && out.addAll(inList);
    }

    public static void main(String[] in) {
        final ArrayList<String> testList = new ArrayList<>(1);
        testList.add("Test strings should never string you along...");
        testList.add("Test String 2!!!");

        final ArrayList<String> resultList = new ArrayList<>(1);
        final StringBuilder tempFileBuffer = new StringBuilder(50);

        try {
            final String resultAbsolutePath = createFilenameAsTempFile(testList);
            tempFileBuffer.append(resultAbsolutePath);
            tempFileBuffer.trimToSize();
        }
        catch (Throwable t) {
            System.out.println("Unable to generate test file");
            t.printStackTrace(System.out);
            System.exit(0);
        }

        try {
            String tempFile = tempFileBuffer.toString();
            System.out.printf("Temp File: %s%n%n", tempFile);

            final boolean result = addArrayListFromFile(resultList, ArrayList.class, tempFile);

            System.out.printf("Method reports it correctly generated output: %s%n", result);
        }
        catch (Throwable t) {
            System.out.println("Calling method generated an error");
            t.printStackTrace(System.out);
            System.exit(0);
        }

        System.out.printf("Method actually did correctly generate output: %s%n%n", testList.equals(resultList));
        System.out.printf("Encoding Input: %s%n", testList);
        System.out.printf("Decoding Output: %s%n", resultList);

    }

    /**
     * Quick and dirty way to generate temporary output file.
     *
     * @param testList The list of objects to serialize and write to the file
     * @return A String containing the absolute file location of a temporary file
     * @throws IOException If the file creation or the streams fail to write or initialize
     */
    private static <T extends Serializable> String createFilenameAsTempFile(final List<T> testList) throws IOException {
        File outFile = File.createTempFile("test-", ".ser");
        outFile.deleteOnExit();
        try (FileOutputStream fos = new FileOutputStream(outFile);
             ObjectOutputStream oos = new ObjectOutputStream(fos))
        {
            oos.useProtocolVersion(ObjectStreamConstants.PROTOCOL_VERSION_2);
            oos.writeObject(testList);
            return outFile.getAbsolutePath();
        }

    }

}