4 replies to this topic

[Turk4n]

Hey C.C !!

I was wondering is it possible to save an entire ArrayList and later read it so it can be use able again?
I haven't found any reliable sources, so I am wondering, could anyone show me how it is performed?
Thanks in advance :)

[chili5]

Sure, why don't you save the array list to a file, and then read it later? Read the stuff into an array list, do whatever you want to with it. Then when you're done with the array list just print it back to the file. :)

public static void main(String[] args) throws IOException {

        Scanner sin = new Scanner(new FileReader("DATA.txt"));

        

        ArrayList<Integer> arnNums = new ArrayList<Integer>();

        

        // read the items into the array list

        while (sin.hasNextInt()) {

            /**

             * as long as the file has another integer to read

             * add it to the array list

             */

            arnNums.add(sin.nextInt());

        }

        

        // print them to a file

        PrintWriter fout = new PrintWriter(new FileWriter("DATA.txt")); 

        for (int index=0;index<arnNums.size();index++) {

            fout.println(arnNums.get(index)); // get the value at the current index and print it to the file

        }

        

        sin.close();

        fout.close();

    }

[Turk4n]

chili5 said:

Sure, why don't you save the array list to a file, and then read it later? Read the stuff into an array list, do whatever you want to with it. Then when you're done with the array list just print it back to the file. :)

public static void main(String[] args) throws IOException {

        Scanner sin = new Scanner(new FileReader("DATA.txt"));

        

        ArrayList<Integer> arnNums = new ArrayList<Integer>();

        

        // read the items into the array list

        while (sin.hasNextInt()) {

            /**

             * as long as the file has another integer to read

             * add it to the array list

             */

            arnNums.add(sin.nextInt());

        }

        

        // print them to a file

        PrintWriter fout = new PrintWriter(new FileWriter("DATA.txt")); 

        for (int index=0;index<arnNums.size();index++) {

            fout.println(arnNums.get(index)); // get the value at the current index and print it to the file

        }

        

        sin.close();

        fout.close();

    }

Will it work with ArrayList<String>??
I will try out in meanwhile thanks for giving me a small demo of it :D

[chili5]

Yeah it'll work with an array list of any data type. :)

[Turk4n]

chili5 said:

Yeah it'll work with an array list of any data type. :)

Tested, and it did :); thanks again :D