Cannot convert from Object array to String array

Programming Questions

mcryach

Cannot convert from Object array to String array

in Programming Questions • 3 months ago

I implemented arrayList to store Strings down the code. I didn't know the size so instead pure Array I implemented the list. I was looking for the way to convert objects from the arrayList to Strings and found how convert the Object to String. At the line 34 PApplet gives me a message "cannot convert from Object[] to String[].

I'm trying sort out the words from XML feed and analyze vocabulary. Could you please help me with arrayList converting.

XML xml;
String[] news = new String[10]; // <<< initiate global arrayList instead
ArrayList wrd = new ArrayList<String>();
int[] reps = new int[1000]; // nubmers 10 (the number of news) and 1000 (the number of words)
int index = 0;
String exceptionWords = "-,of,the";
String[] junctions = split(exceptionWords, ",");
void setup() {
xml = loadXML("http://www.reuters.com/rssFeed/topNews"); // Adress of XML
XML channel = xml.getChild("channel"); // Getting into the channel of the XML
XML[] items = channel.getChildren("item/description"); // Gets into item and then in item gets into description
//String[] news;
for (int i = 0; i < items.length; i++) { // iterate through all elements "description"
//println(items[i].getContent()); // Prints the content of the element "description"
news[i]=(items[i].getContent()); // Record news into the GLOBAL String array
}
//println(news);
String words = join(news, ' '); // Join all elements of the array "news" into a single String
String[] wordsArray = split(words, " "); // Create array of words from the text "news"
for (int i = 0; i < wordsArray.length; i++) {
for (int j = 0; j < junctions.length; j++) {
if (wordsArray[i] != junctions[j]) {
wrd.add((String)wordsArray[i]);
index++;
println(index);
} else {
}
}
}
String[] wordsCopy = wrd.toArray(new String[wrd.size()]);
//println(junctions);
for (int i = 0; i < wrd.length; i++) { // For loop to get item from wordsArray for comparisson
for (int j = 0; j < wordsCopy.length; j++) { // For loop to run through every word in wordsCopy comparing the singel element from wordsArray
if (wrd[i].equals(wordsCopy[j]) == true) {
reps[i] = reps[i] + 1;
}
}
println(wordsArray[i] + " " + reps[i] + " times ");
}
//println(wordsArray);
}

Replies(2)

GoToLoop

Re: Cannot convert from Object array to String array

3 months ago

I believe the error lies at line #3:
ArrayList wrd = new ArrayList<String>();

The formally correct Java's syntax is:
ArrayList<String> wrd = new ArrayList<String>();

That is, you specify the data-type being stored both for the recipient variable ( wrd)
and for the object being created.

However for Processing, it's enough to specify the generics for the recipient variable alone:
ArrayList<String> wrd = new ArrayList();

I like this way better b/c it's much less verbose.

All of that is necessary b/c a Collection can store mixed data-types within it.
And consequently, when accessing its content, Java doesn't know what would come outta it!

So, specifying the genetics right at the declaration makes sure to Java compiler what's inside of it!

There are more bugs like 1 at line #36:
for (int i = 0; i < wrd.length; i++) {

For a Collection, we don't directly access a field variable ( length) as we do for a regular Array.
Instead, we have to use its method size():
for (int i = 0, ii = wrd.size(); i != ii; ++i) {

PhiLho

Re: Cannot convert from Object array to String array

3 months ago

" I like this way better b/c it's much less verbose."
I dislike it way more, because it gives bad habits if you ever have to code in plain old Java...

And I don't think Processing supports the diamond operator of Java 7:
ArrayList<String> things = new ArrayList<>();
For the record, the great Guava library offers a facility (pre-dating the Java 7 syntax):
ArrayList<String> things = Lists.newArrayList();

Otherwise, good advices and analysis...