String Array conversion issue - complete noob HELP!!!

Programming Questions

eess13

String Array conversion issue - complete noob HELP!!!

in Programming Questions • 3 years ago

Hi all, apologies if this has been asked before - I've searched the forum and didn't find anything...

I'm a complete novice to Processing, and I'm three-quarters through a simple project - designing a presentation lesson using Processing.

I've spent days working out nice animations, etc, and now I've hit a complete dead end...

When trying to load the text file with the numerous lines of the presentation, I get the "cannot convert from String to String[]".

I have limited coding skills, but I'm aware that there should be some method to call - Googling the error, I found ways around this in other languages, but cannot get these to work.

I simply want to display 8 lines of text within the display, and, once a mouse click occurs, the next 8 lines replace the current lines.

I've stripped out the rest of the code, and the problematic code is below:

int lineCount = 0;
int lineSize = 35;

public String lines[] = dataPath("list.txt");

void setup() {
size(800,560);
PImage img;
img = loadImage("green-blank-blackboard.jpg");
background(img);
PFont font;
font = loadFont("KristenITC-Regular-32.vlw");
textFont(font, 32);
}

void draw() {
noStroke();
noFill();

}
void mouseClicked(){

//String lines[] = loadStrings("list.txt");

    for (int i=lineCount; i < lineCount; i++) {
    text(lines[i],40,lineSize*i*2);
    }
    lineCount = lineCount + 8;
}

Any help would be greatly appreciated, as I've wasted loads of time making the rest look pretty, and I'm burned out at this stage!

Replies(7)

guy_yitzh..

Re: String Array conversion issue - complete noob HELP!!!

3 years ago

Why not use loadStrings? This piece of code should work.

String lines[];
int lineCount = 0;
void setup() {
.....
lines = loadStrings("list.txt");
lineCount = lines.length;
...
}

Also, I'm not sure if it is an error or just a leftover from code you left out but in the loop you probably mean

for (int i=0; i < lineCount; i++)

and not

for (int i=lineCount; i < lineCount; i++)

(as the second option does nothing).

eess13

Re: Re: String Array conversion issue - complete noob HELP!!!

3 years ago

Thanks for the loop help, it's one of my "do'h" moments...

That worked great it was similar to one of my earlier attempts, but the main problem then is how do I display the next 8 lines - I can click, get the first 8 lines to display, but when I click again, nothing happens - I just need to be able to rotate through the array lines per click, if possible?

ledled

Re: String Array conversion issue - complete noob HELP!!!

3 years ago

Being new to processing myself too this might not be the answer but I think it could help - have you looked at pages 306 to 308 in Processing a programming handbook for visual designers and artists? If you don't have the book I can post the code that seems most relevant to what you want to do so you can adapt it to your own purposes.

blindfish

Re: String Array conversion issue - complete noob HELP!!!

3 years ago

Presumably you want something like this:

int startIndex = 0;
public String lines[] = new String[35];
void setup() {
size(800,560);
for (int i=0; i<lines.length; i++) {
lines[i] = "foo " + i;
}
}
void draw() {
noStroke();
noFill();
}
void mouseClicked(){
if(startIndex < lines.length){
int upperLimit = lines.length;
if(startIndex + 8 < upperLimit){
upperLimit = startIndex + 8;
}
for (int i=startIndex; i < upperLimit; i++) {
println(lines[i]);
}
println("---");
startIndex += 8;
}
}

As guy_yitzhaki pointed out; the problem with your version was that your for loop wouldn't do anything; but you were on the right track. You could have tried:

for (int i=lineCount; i < lineCount+8; i++) {
// draw line
}
lineCount += 8;

But then you'd probably run into an outOfBounds error when you got to the end of the array... I couldn't be bothered setting up a file with a text file and fonts etc; but it should hopefully be easy enough to apply the principle to your usecase...

eess13

Re: Re: String Array conversion issue - complete noob HELP!!!

3 years ago

Hi guys, many thanks for the quick replies! Surprisingly, I was headed on the right track with a lot of these replies, before I scaled it back to simplify the problem..

Slept on it last night (I'm in Ireland!) and got back on it this morning - I'm getting somewhere, but I've realised I need to simplify my code even further before getting it to work properly - many thanks to blindfish's code, which I adapted, I've worked out some of the simple issues but still get a problem:

int lineCount = 0;
int upperLimit = 0;
int lineSize = 35;

public String lines[] = new String [50];
//(Not looking at the loadStrings vs dataPath issue, see below)

void setup() {
size(800,560);
PImage img;
img = loadImage("green-blank-blackboard.jpg");
background(img);
PFont font;
font = loadFont("KristenITC-Regular-32.vlw");
textFont(font, 32);
for (int i=0; i<lines.length; i++) {
lines[i] = "foo " + i;

}
}

void draw() {
noStroke();
noFill();

}
void mouseClicked(){

if(lineCount < lines.length){
upperLimit = lines.length;
}
if(lineCount + 8 < upperLimit){
upperLimit = lineCount + 8;
}

for (int i=lineCount; i < upperLimit; i++) {
text(lines[i],40,lineSize*i*2);
// (This is to check that lines[] is still incrementing x 8 each click)
println(lines[i]);
}
lineCount = lineCount + 8;
}

The code works in that the array is still being read up to it's limit (using println, I can see the array being read correctly), but I still can't get around this bit-

Once the first 8 lines are displayed, I want to clear the display, and replace the first 8 lines with the next 8 lines - the code above still works, but the next lines are displayed after the initial lines (and outside of the display field).

Again, it's probably some simple thing I'm tiptoeing round the edges of, but just need a push....cheers!

blindfish

Re: String Array conversion issue - complete noob HELP!!!

3 years ago

OK; this should be simple enough to resolve: you don't repeat the call to background so anything you render to the screen persists; so even if you did get the text in the right place it would be layered on top of the previous text leading to a horrible mess :)

To solve that you'll need to call background again: simples :)

The position problem is caused by the fact that you're calculating the y position based on the value of i:

text(lines[i],40, lineSize*i*2);

But remember that the starting value of i is based on the value of lineCount, which is incrementing by 8 each time this loop is called. Two possible solutions to this:

1. text(lines[i],40, lineSize*(i-lineCount) * 2);
2. Or a slightly more advanced use of a for loop with two variables:

for (int i=lineCount, j=0; i < upperLimit; i++, j++) {
text(lines[i],40,lineSize*j*2);
}

In this case the variable j always starts at 0...

eess13

Re: Re: String Array conversion issue - complete noob HELP!!!

3 years ago

blindfish,

thanks again, the loop with two variables worked a treat!

stuck a second PImage in mouseClicked(), works great.....

created a second String array in setup() to loadStrings from the text file, then:

String content[] = loadStrings("list.txt");
for (int i=0; i<lines.length; i++) {
lines[i] = content[i];

Works great!!

Thank you so much, I can breathe easy, and go back to adding in all the pretty 'wipe' animations I spent waaaaaay too much time on.... thanks again!