Why am I getting this dynamic IndexOutOfBounds Exception? - class

Question

I am trying to write a program where text is translated into hexadecimal, then into decimal, and then into an (R, G, B) format. However, when trying to incorporate ClickableRectangle, I get an ArrayIndexOutOfBounds exception that changes dynamically with the sign of rects.
Any thoughts on my problem/optimization?
char[] colors; //Array of characters to be translated into hexadecimal
String r = ""; //Red value of color
String g = ""; //Green value of color
String b = ""; //Blue value of color
int x = 0; //X-coordinate of rectangle
int y = 0; //Y-coordinate of rectangle
int q; //Character count
ClickableRectangle[] rects = new ClickableRectangle[400*400]; //Rectangles
void settings() {
size(displayWidth, displayHeight);
}
void setup() {
background(0);
colors = new char[3];
String s = ([INSERT TRANSCRIPT HERE]); //Too long to be in post//
for (int i = 0; i < s.length(); i+=3) {
for (int j = i; j < i+3; j++) {
colors[j-i] = s.charAt(j);
}
r = hex(colors[0], 2);
g = hex(colors[1], 2);
b = hex(colors[2], 2);
drawAPoint(r, g, b, i);
println(i);
q++;
}
save("SlachtochtFeuf.png"); //Ignore this, using for testing purposes
println("q = " + q);
println("x = " + x);
println("y = " + y);
}
void draw() {
for (int i = 0; i < rects.length; i++) {
if (rects[i].isClicked()) {
println(rects[i].getValue()); //Prints char representation of color
}
}
}
void drawAPoint(String r2, String g2, String b2, int i) {
noStroke();
fill(unhex(r2), unhex(g2), unhex(b2));
rects[i] = new ClickableRectangle(x, y, r2, g2, b2);
rects[i].display();
if (x >= width) {
x = 0;
y += 6;
} else {
x+=6;
}
}
class ClickableRectangle {
int x = 0;
int y = 0;
String r = "";
String g = "";
String b = "";
public ClickableRectangle(int x, int y, String r, String g, String b) {
this.x = x;
this.y = y;
this.r = r;
this.g = g;
this.b = b;
}
public void display() {
fill(unhex(r), unhex(g), unhex(b));
rect(x, y, 6, 6);
}
public void setRGB(String r, String g, String b) {
this.r = r;
this.g = g;
this.b = b;
}
public String getValue() {
return ""+char(unhex(r))+char(unhex(g))+char(unhex(b));
}
public boolean isClicked() {
return mouseX > x && mouseY > y && mouseX < x+6 && mouseY < y+6;
}
}

Answer 1

For future reference, you should tell us exactly which line throws the exception, and you should include all of the code needed to repeat the problem. If the text is too long to post, then narrow it down to a smaller MCVE.
But judging from what I can see, the problem appears to be here:
String s = "test";
for (int i = 0; i < s.length(); i+=3) {
for (int j = i; j < i+3; j++) {
colors[j-i] = s.charAt(j);
}
//other stuff
}
Just run through this in your head:
When i=0 and j=0, you access charAt 0.
When i=0 and j=1, you access charAt 1.
When i=0 and j=2, you access charAt 2.
When i=3 and j=3, you access charAt 3.
When i=3 and j=4, you access charAt 4.
You could also use println() statements to better see what's going on:
for (int i = 0; i < s.length(); i+=3) {
println("i: " + i);
for (int j = i; j < i+3; j++) {
println("j: " + j);
colors[j-i] = s.charAt(j);
}
//other stuff
}
That prints out:
i: 0
j: 0
j: 1
j: 2
0
i: 3
j: 3
j: 4
That last part is the problem- the String I'm using is "test", so it only has 4 characters: charAt(0), charAt(1), charAt(2), and charAt(3). So when you try to access charAt(4), it throws a StringIndexOutOfBoundsException!
I don't know exactly what you're trying to do here, but you'll have to rework your code so that it doesn't try to access characters outside the bounds of the String.
As a side note: it looks like you're trying to code your whole project all at once. Don't do that. Instead, develop this in small increments- try to get smaller pieces working by themselves before you combine them into your whole project. Can you write a separate sketch that simply loops over a String and prints out the characters you're trying to extract? Then if you get stuck, you can use that smaller sketch as your MCVE, and it'll be easier for us to help you.