如何使用JFileChooser保存/加载ArrayList数组？

Question

I have the following code:

ArrayList<String> [] hotelArray = (ArrayList<String>[ ]) new ArrayList[5];
for (int i = 0; i < 5; i++) {
    hotelArray[i] = new ArrayList<String>();
}

hotelArray[0].add("NY hotel1");
hotelArray[0].add("NY hotel2");
hotelArray[0].add("NY hotel3");
hotelArray[2].add("Japan Hotel");
    hotelArray[2].add("Japan Hotel2");
hotelArray[3].add("Nova Hotel");
hotelArray[4].add("Tokyo hotel");

Now I want to know, how do I save hotelArray to a single file, using JFileChooser. Also how do I read file using JFileChooser ? When I am reading, can I restrict to just reading say hotelArray[0] elements?

Answer 1

In the beginning the JFileChooser does nothing else than pick a filename and give you the file behind the name. What you need first is a method to write a file (just write down the filename in your code and change that part later). Read this one page tutorial on how to write some text into a file . And here is a little peace of code, that shows you how to read a file line by line.

Now you only have to iterate through your ArrayList and write each list entry as a new line into your file. The same way you can read it back from the file into the ArrayList

Answer 2

JFileChooser returns you a File object. And then you are free to do everything with it. Have look at manual first.

Answer 3

JFileChooser either selects a file from the disk to be read, or selects / creates a file to be written.

The file format it up to you. You have to convert the Java object(s) to bytes that can be written to and read from the disk.

Some people would say to serialize the Java object(s). However, this is an inflexible method. If you add or take away any fields from your Java object(s), your serialization changes.

You can write your Java object(s) to a Java Properties file. This is a good choice if you have a limited amount of data to write to the disk.

You can write your Java object(s) in XML. This is a good choice if you want to maintain a hierarchical relationship with your Java object(s).

You can write your Java object(s) to a relational database like SQLite . This is a good choice if you have many relational Java object(s).