I am trying to populate an ArrayList using a loop. What am I doing wrong? When I print the ArrayList nothing gets printed. I think my problem is related to numbers.size().
ArrayList<Integer> numbers = new ArrayList<>(7);
for (int i = 1; i <= numbers.size(); i++) {
numbers.add(i);
}
In line ArrayList<Integer> numbers = new ArrayList<>(7); 7 - isn't size. Size still equal 0, because you didn't add any elements. So numbers.size() is 0.
Argument in constructor is initialCapacity. This is a start length of internal array in ArrayList.
i <= numbers.size() to i <= 7
int SIZE to your desired length and then do for int i = 0; i < SIZE; i++Initially, the list is empty, meaning numbers.size() returns 0. Therefore the loop will never be entered because 1 <= 0 is false.
The problem is with numbers.size(). This line ArrayList<Integer> numbers = new ArrayList<>(7); create an ArrayList with initial capacity enough equal or higher than 7 but the size of the created ArrayList is 0. So the program doesn't go instead your loop
You have two problems here:
ArrayList<Integer> numbers = new ArrayList<>(7);
You need to specify the type for both sides of the assignment
for (int i = 1; i <= numbers.size(); i++) {
numbers.add(i);
Indexes for arrays and ArrayLists start at 0, so make i zero, and use a less-than instead of less-than-or-equal-to. Finally, this should work. Just edited this, seems like I was slightly wrong. Make numbers.size() a constant instead, and that should work
ArrayList<Integer> numbers = new ArrayList<Integer>(7);
for (int i = 0; i < 7; i++) {
numbers.add(i);
}
<> instead of rewriting generic type again.