遍历ArrayList <Object> 使用for循环

Question

Im having a problem with my for loop for iterating over an ArrayList that hold objects. I make an ArrayList that hold these items, LumberItem is just a String for the name and an int for the amount.

ArrayList<LumberItem> lumberList = new ArrayList<LumberItem>();

LumberItem wood1 = new LumberItem("Oak", 1500);
lumberList.add(0, wood1);
LumberItem b = new LumberItem("Pine", 1500);
lumberList.add(1,b);
LumberItem c = new LumberItem("Cedar", 1500);
lumberList.add(2, c);
LumberItem d = new LumberItem("Maple", 1500);
lumberList.add(3, d);
LumberItem exp = new LumberItem("Birch", 1500);
lumberList.add(4, exp);

I try to use a for loop like so

for(int i = 0; i < lumberList.size(); i++) {
    contentTA.setText(lumberList.get(i).getType());
    contentTA.append("\n at index" + i + "\n");
}

My output consists of only the last element in my ArrayList so, Birch is outputted. I have tried using different methods of looping like

for(LumberItem l : lumberList)

I am still at the end of my ArrayList when I try and output. I wondering why this is happening since I haven't figured it out.

Answer 1

So I'm an idiot, I was using .setText() which will clear the JTextArea every time I call it, so it should be .append()!

for(LumberItem L : lumberList) {
    contentTA.append("\n" + L.getType());
}

or

for(int i = 0; i < lumberList.size(); i++) {
contentTA.append(lumberList.get(i).getType());

Will work. Hopefully my poor reading skills help out someone else!