push a string into an array

Programming Questions

lukasz

in Programming Questions • 1 year ago

how would do the equivalent in Java as array.push(string); in java? I can't seem to get it to work correct, some research lead me to ArrayList but I can't find any good references that explain it well.

Trying to play around with a twitter example and actually render the text, here is what I have so far:

PFont f;
ArrayList al = new ArrayList();
void setup() {
size(780, 600);
f = createFont("Arial", 16, true); // STEP 3 Create Font
ConfigurationBuilder cb = new ConfigurationBuilder();
// replaced actual values with ****
cb.setOAuthConsumerKey("****");
cb.setOAuthConsumerSecret("****");
cb.setOAuthAccessToken("****-****");
cb.setOAuthAccessTokenSecret("****");
Twitter twitter = new TwitterFactory(cb.build()).getInstance();
Query query = new Query("#keyword");
query.setRpp(100);
try {
QueryResult result = twitter.search(query);
ArrayList tweets = (ArrayList) result.getTweets();
for (int i = 0; i < tweets.size(); i++) {
Tweet t = (Tweet) tweets.get(i);
String user = t.getFromUser();
String msg = t.getText();
Date d = t.getCreatedAt();
println("Tweet by " + user + " at " + d + ": " + msg);
al.add(msg);
};
}
catch (TwitterException te) {
println("Couldn't connect: " + te);
};
}
void draw() {
background(255);
textFont(f, 16);
fill(0);
for(String msg : al){ // this is shorthand... I think?
// also tried: for(int i = 0; i < al.length; i++){
// which gave me error that al.length cannot be resolved or is not a value
text(al[i], 10, i+20);
}
}

I can definitely get it to get the messages from twitter, but I get this error: cannot convert from element type Object to string

Replies(2)

akiersky

Re: push a string into an array

1 year ago

Hi lukasz,

I would try adding '(String)' before you get the al[i] to cast what was stored as a string. like this:

text((String) al[i], 10, i+20);

but this wouldn't work in this case because you are using the shorthand for loop, and you don't have an 'i' variable. the shorthand you are using iterates through each of the values stored in 'al' and puts the value into a string variable 'msg'. so when you draw the text to the stage, you can simply do this:

text(msg, 10, i+20);

Also, when you know what data type you are going to be storing, it is better to use that object's array. for example rather than storing Strings in an ArrayList, just use 'String[] al'. The downside is that you have to know how big the array is going to be, but adding and removing is much faster. That may not work in this case since you wouldn't know how many tweets you are getting back.

good luck!

PhiLho

Re: push a string into an array

1 year ago

See http://processing.org/reference/ArrayList.html
The article Why use ArrayList instead of array with append()? also gives some explanations on this class.
ArrayList, despite the name, isn't an array, so you cannot use al.length (that's al.size()) nor al[i] (that's al.get(i)).