Question

for (int j =0; j < marks.size(); j++) {
    analyzeTextArea.setText(j + marks.get(j));
}

The above code gives me the following error:

required: java.lang.String found: int

Answer 1

I guess marks.get(j) give you an Integer. So when you do j + marks.get(j) you add the value of marks.get(j) to the value of j.

So you end with an Integer as result of j + marks.get(j). But setText expect a String.

You have several possibilities now depending on you needs.

analyzeTextArea.setText(Integer.toString(j + marks.get(j)));

This case still make the addition then convert it to String in order to respect setText parameter type.

With this :

analyzeTextArea.setText("" + (j + marks.get(j)));

"" tells that the parameter will be a String and then you will concatenate j and marks.get(j). So, for example, for the first loop you will have something that start with 0

Now using setText in a loop don’t really make sense because only the last value set in the loop will be used you probably should use JTextArea#append(String).