converting hashmap to stringarray

Question

I am trying to convert a hashmap into an array, that I can put in a created string array. I however get java.lang. I have typeconverted my drinkar.keySet().toArray() to String[], but it will still not work.

public String[] receiveArrayList(){

String[] list = new String[0];

    try {
        ois = new ObjectInputStream(socket.getInputStream());
        drinkar = (HashMap<String, ArrayList<String>>) (ois.readObject());
        System.out.println(drinkar);

        System.out.println(Arrays.toString(drinkar.keySet().toArray()));
        list = (String[]) (drinkar.keySet().toArray());

        for(int i = 0; i < list.length; i++){
            System.out.println(list);
        }


    } catch (ClassNotFoundException ex) {
        System.out.println(ex);
    } catch (IOException ex) {
        System.out.println(ex);
    }
    return list;

}

score 9 · Answer 1 · answered Aug 22 '12 at 18:38

Use toArray(T[]) as:

String[] list = drinkar.keySet().toArray(new String[0]);

By giving an empty array as the argument, you tell toArray to create a new array of the same type for you that will be just of the correct size.

Just a note: If you can choose, it's usually more convenient (and safer) to work with collections such as ArrayList instead of arrays.

score 4 · Accepted Answer · answered Aug 22 '12 at 16:48

4

drinkar.keySet().toArray() returns Object[] not String[]

One of the way may be:

user Collections.toArray(StringArry)

(or)

Iterate through the keySet and add each element to array.

answered Aug 22 '12 at 16:48

kosa

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thanks, but i cant seem to get it right. i dont think i know how to iterate correctly. – DrWooolie Aug 22 '12 at 17:41
while(it.hasNext()){ String temp = it.next(); //then add temp to String array. } – kosa Aug 22 '12 at 17:46
is there a way to add strings to arrays? doesnt seem like it – DrWooolie Aug 22 '12 at 17:54
arr[0]=temp; this will add temp at index 0 – kosa Aug 22 '12 at 17:58
it didnt work, i still get nothing. but i tried another way. created an arraylist, added temp to the arraylist and it worked and i could print it easily. but when i tried to convert it to array, it gave me java.lang. – DrWooolie Aug 22 '12 at 18:02

score 1 · Answer 3 · answered Aug 24 '13 at 19:57

1

String st[]=hm.keySet().toArray(new String[hm.size()]);

answered Aug 24 '13 at 19:57

Jay Shah

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score 0 · Answer 4 · answered Aug 22 '12 at 18:11

0

Another option is create ArrayList<type> and add elements and return list.toArray(). This is exactly what toArray does on entryset Can not type code since not front of desktop

answered Aug 22 '12 at 18:11

Amit Deshpande

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converting hashmap to stringarray

4 Answers4

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