Modify the first part of Code 2 to

1. String[] fLines;
2. int folderCount;
3. int i=0;
4. 
   
5. void setup() {
6.    size(400, 400);
7.    fLines = loadStrings("test.txt");
8.    folderCount = fLines.length;
9. }

This will get rid of the null pointer expression (change the filename to suit yourself.)

I have corrected your array declaration - see line 1 (the [] come after the data type not the array name. Also the reading of the file has been moved to setup which allows the sketch to initialise before attempting to read the file.

Although the program runs you will get an ArrayIndexOutOfBoundsException because you have no restriction on the variable i (increments forever - modify draw to

1. void draw() {
2.   if ( i < folderCount) {
3.     println(fLines[i]);
4.     drawStatus(i);
5.     i++;
6.   }
7. }

Oh okay. I see now I was mixing up where to declare what--but I see the pattern.

Complete working code for progress bar below

1. //Test for progress bar reading lines in testzipcodes.txt instead of files
2. PFont font;
3. String[] fLines;
4. int folderCount;
5. int i=0;
6. void setup() {
7.   size(400,400);
8.   font = loadFont("ArialRoundedMTBold-48.vlw");
9.   fLines = loadStrings("testzipcodes.txt");
10.   folderCount = fLines.length;
11. }
12. void draw() {
13.   background(217, 222, 222);
14.   i++;
15.   if(i < folderCount) {
16.     drawStatus(i);
17.   }
18. }
19. /*Progress Bar
20. Must have preloaded font and folderIndex and folderCount variables*/
21. void drawStatus(int folderIndex) {
22.   float statusX = 30;
23.   float statusY = 60;
24.   float statusH= 20;
25.   float statusW = width - statusX*2;
26.   if(folderIndex != folderCount) {
27.     int percentComplete = int(float(folderIndex)/float(folderCount)*100.0);
28.     fill(255,255,255);
29.     textFont(font);
30.     textSize(14);
31.     text("Processing... " + nf(percentComplete, 3) + "% Complete", statusX, statusY-10);
32.   }
33.   else {
34.     fill(255,255,255);
35.     textFont(font);
36.     text("Finished processing folders", statusX, statusY-10, statusW, statusH);
37.   }
38.   fill(224, 217, 217);
39.   rect(statusX, statusY, statusW, statusH);
40.   fill(224, 57, 205);
41.   float completedW = map(folderIndex, 0, folderCount, 0, statusW);
42.   rect(statusX, statusY, completedW, statusH);
43. }
44.  

Every beginner in Java makes this error. In 6/100 you divide an integer with another, the result is an integer. If you had 3/2, you will get 1. Here, you just get zero. Simple solution: do a cast to a float. Or use a float in the expression. For example: 100.0 * fileIndex / fileCount
Here, 100.0 must be first, so that the multiplication is a float too, and the division too.

Thanks!