Build Software Applications

How do I find the filename of a file?

You can use the File method .getName()
I’m confused about how to use an ArrayList as the value within a HashMap. How do I create and update an ArrayList for each word?

Each word should map to a separate ArrayList. When you encounter a key that isn’t already in the HashMap, you should create a new ArrayList and use HashMap.put() to insert the key and its associated ArrayList. When you want to add to the ArrayList of a key that is already in the HashMap, you should use HashMap.get() to get the ArrayList, update it, then use HashMap.put() to put the key and the updated ArrayList back into the HashMap.
I’m not sure how to go about not reusing words in GladLibs. How do I make sure the new word hasn’t been used already? Where do I write this code?

Think about what type of a loop you will need – do you know how many times this loop will need to run? When will you want to stop the loop? To figure out where to add this code, think about where you generate new words and when you could check whether these have been used already.
Why am I getting a null pointer exception whenever I try to call a method on my HashMap?

Make sure you have initialized your HashMap before calling methods on it. Also, if you are declaring and initializing it in different places, make sure that you have not declared it a second time when you initialize it.
My LogAnalyzer class prints out all the values correctly except for the date/time. Does the time zone setting in the computer have an impact on the output value from the .getAccessTime() method?

Yes, if your time zone is different from Durham, USA, you may want to temporarily change the time zone on your computer.
Where can I find the dictionary files to use for my VigenereBreaker?

The dictionary files are included in the starter program you download. They are inside the folder called ‘dictionaries’.

Frequently Asked Questions