Enhanced For Loop to General For Loop

Programming Questions

Jesse Sco..

Enhanced For Loop to General For Loop

in Programming Questions • 2 years ago

Hi... playing with one of the Sensebloom Processing examples ( here), for receiving OSC values from osceleton...

There's a Skeleton Class, with a bunch of arrays for each xyz position of a skeleton joint, then an array named allCoords that holds each of those within it...

In the draw() function, it's called like this:

for (Skeleton s: skels.values()) {
stroke(s.colors[0], s.colors[1], s.colors[2]);
for (float[] j: s.allCoords) {
pushMatrix();
translate(j[0]*width, j[1]*height, -j[2]*100);
sphere(20);
popMatrix();
}

So, getting down to my question, I'm trying to draw vertexes (vertices ?) between the points, but I'm having a little trouble unpacking the way the For Loop is written. I've found this page on the Oracle site that explains it is an 'Enhanced For Loop' for dealing with arrays...

I want to rewrite it into a 'General' for loop, but am getting a bunch of errors:

for (int j = 0; j < s.allCoords; j++) {

returns "The operator < is undefined for the argument type(s) int, float[][]"

for (int j = 0; j < s.allCoords[]; j++) {

and

for (float j = 0; j < s.allCoords[]; j++) {

returns "Syntax error on token"[", Expression expected after this token"

... so, I'm stuck. Any ideas welcome. Or... if anyone has already modified this example to draw a proper skeleton instead of spheres at the joints, that code would be welcome too (thought I do want to understand this...)

thanks,

~ J

Replies(3)

Jesse Sco..

Re: Enhanced For Loop to General For Loop

2 years ago

Sorry, I realize that the example I linked to (meant to do the other one) actually has the bones/skeleton, so I'm fine.

But if anyone is feeling up for explaining the Enhanced For syntax...

PhiLho

Re: Enhanced For Loop to General For Loop

2 years ago

I was wondering why you wanted to transform the for loop, since Processing now supports this syntax...

This form is nice but have limitations (sometime you need an index too).
On arrays, it just works on iterating over all the indices:
for (ArrayType element : arrayOfSomeType) { use(element); } is like:
for (int i = 0; i < arrayOfSomeType .length; i++) { use(arrayOfSomeType[i]); }

Slightly less verbose and, IMO, more readable.
But it really shines when it is used over a collection, ie. an object implementing the Iterable interface.
Instead of iterating over indices and using get() or similar, or using the heavy Iterator syntax, you just write:
for (CollType element : collectionOfType) { use(element); }

Syntax similar to array's one, so improved consistency, and simplicity.

The article http://www.java-tips.org/java-se-tips/java.lang/the-enhanced-for-loop.html looks interesting too.

Jesse Sco..

Re: Enhanced For Loop to General For Loop

2 years ago

It's just that I didn't really understand the syntax, so wasn't sure if it was acting the same...

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