IndexOutofboundException ¿Por qué?

Question

Tengo un problema pequeño que obtuve Error java.lang.indexoutofboundsexception: Índice: 29, tamaño: 29 Cuando inicie este error de código está en la línea if ((listaSwiat != null && listaSwiat.get(x) != null) || harm.get(y).getDzienTygodnia(x + 1).equals("Nd")), pero no dunno, ¿por qué el índice no debe ser de 30 NO1, puede ayudar?

for (int y = 0; y < harm.size(); y++) {//wiersze
            c1 = new PdfPCell(new Phrase(harm.get(y).nazwa, stdFont));
            c1.setHorizontalAlignment(Element.ALIGN_CENTER);
            table.addCell(c1);
            c1 = new PdfPCell(new Phrase("" + harm.get(y).getSumaGodzin() + " / " + harm.get(y).normaGodzin, smallFont));
            c1.setHorizontalAlignment(Element.ALIGN_CENTER);
            table.addCell(c1);
            for (int x = 0; x < harm.get(y).dni.size(); x++) {//kolumny
                c1 = new PdfPCell(new Phrase(harm.get(y).dni.get(x).godziny, smallFont));
                //dla swiąt ustal kolor tła na czerwono
                //dla niedziel ustala kolor tla na czerwony
                if ((listaSwiat != null && listaSwiat.get(x) != null) || harm.get(y).getDzienTygodnia(x + 1).equals("Nd")) {
                    c1.setBackgroundColor(BaseColor.RED);
                }

Answer 1

It looks like you are looping over all the elements of harm.get(y).dni and inside the loop you do

if ((listaSwiat != null && listaSwiat.get(x) != null) 
|| harm.get(y).getDzienTygodnia(x + 1).equals("Nd"))

The last time through the loop x = 28 and the size is 29. But you do

harm.get(y).getDzienTygodnia(x + 1)

So you get the element at spot 29 which is out of bounds, because like the other answer stated the index starts at 0 not 1. You have to add a check here to see if you are currently at the last index before checking the next index.

Answer 2

In Java (and many other programming languages), indices start at zero, not one.

This means that, if the size is 29, the last valid index is 28, not 29.

Answer 3

Break apart the line that causes the exception so you can see exactly which call to get is failing.

boolean listaSwiatCheck = listaSwiat != null && listaSwiat.get(x) != null;
if (listaSwiatCheck || harm.get(y).getDzienTygodnia(x + 1).equals("Nd")) {
    c1.setBackgroundColor(BaseColor.RED);
}