How to store a list of objects to memory for later use

Question

I am trying to write a program which will help manage some data. So far, the user can create a new file using a "New File" Dialogue. After the user has entered some parameters, I create a new instance of a "File" class. My questions now is: How can I store multiple files (like tabs) in memory. I was thinking about using some sort of ArrayList as a variable in an "Application" class. What would be an ideal approch here?

Answer 1

You can use a map to store your files in memory.

public class FileStorage{

    Map<String, File> fileMap;

    public FileStorage(){
        fileMap = new HashMap<String, File>();
    }

    public void addNewFile(File f, String fileName){
        if (fileMap.get(fileName) != null){
            // Do something if you do not want to erase previous file...
        else{
            fileMap.put(fileName, f);
        } 
    }

    public File getStoredFile(String fileName){
        File f = fileMap.get(fileName);
        if (f==null){
            // alert user the file is not found.
        }
        return f; 
    }

}

Then in your main class you can simply use the FileStorage class to manage your files

public static void main(String[] args){
    FileStorage fileStorage = new FileStorage();

    // User create a new file
    File file1 = new File();

    fileStorage.addNewFile(file1, "file1"); // name can also be file1.getName()

    [...]

    // Later you can access the file
    File storedFile = fileStorage.getStoredFile("file1");
}

The complexity to access or store file is O(1). It is better than a list for accessing a file.