Question

Here is my issue: I need to write the Interator to the file “random.txt” I am able to see all the data. The data is Store where suppose to, I can see it with the System.out.print but my file is in blank. I am able to create the file but not to writer to it.

I am reading a file from my comp. store in the Treemap and trying to write to the text file. ( I am able to doit with Array with not problem) But this Map with Iterator is bouncing my head.

If some one can help me a litter I will appreciated.

I need to use the TreeMap and the Iterator.

public static void main(String[] args) throws FileNotFoundException, IOException {
    Map<String, String> Store = new TreeMap<>();

    Scanner text=new Scanner(System.in);

    System.out.println("enter file:  ");


    //C:\Users\Alex\Desktop\Fruits\fruits.txt           

    String rap=text.next();

    File into = new File(rap);

    try (Scanner in = new Scanner(into)) {                

        while (in.hasNext()){
            String name=in.next();
            String fruta = in.next();
            Integer num= Integer.parseInt(in.next());
            System.out.println(fruta+"\t"+name+"\t"+num);

            if (Store.containsKey(fruta)){
                Store.put(name,Store.get(name)+fruta );
            }
            else{
                Store.put(name,fruta);
            }
        }

        in.close();

    }                                                                

    System.out.println();

    // insert data to store MAP 
    Set top=Store.entrySet();
    Iterator it = top.iterator();  

    // debugging 

    System.out.println(top);

    // Creating file???????
    FileWriter fstream = new FileWriter("random.txt");  

    //identify File to be write?????? 
    BufferedWriter out = new BufferedWriter(fstream);

    //iterator Loop       
    while(it.hasNext()) {

        Map.Entry m = (Map.Entry)it.next();
        String key = (String)m.getKey();
        String value = (String)m.getValue();

        //writing to file?????
        out.write("\t "+key+"\t "+value);

        // debugging 
        System.out.println(key +"\t"+ value);
    }       

    System.out.println("File created successfully.");
}

Answer 1

After your while loop (the one writing to file) is finished, do:

out.flush();
out.close();

Short explanation: BufferedWriter buffers in memory what you write. It doesn’t immediately write to file when you call the write method. Once the while loop is finished and the data to write to file is prepared in buffer memory, you should call flush to do the actual writing to hard disk. And finally you should always close the BufferedWriter that will no longer be used, to avoid memory leaks.