Java ArrayList of Integer []，如何访问元素

Question

I am using an ArrayList of to create lists. For example:

Index 0: 1 3
Index 1: 4 5
Index 2: 1 3 7

How can I access the second element of the first index of the ArrayList? Couldn't find the answer on Google, so I asked here.

Answer 1

yourList.get(0)[1]; // that's it !!

If you want to iterate over it :

for (Integer[] outer : yourList) {
  for(Integer inner : outer) {
    System.out.println(inner);
  }
}

Answer 2

By your question, I am guessing you have something like this?

List<Integer[]> list = new ArrayList<Integer[]>();
Integer[] a1 = {1,3};
Integer[] a2 = {4,5};
Integer[] a3 = {1,3,7};

list.add(a1);
list.add(a2);
list.add(a3);

Then all you need to do is simply call:

Integer result = list.get(0)[1];

The get(0) pulls the first Integer[] out of the list, then to get the second element, you use [1]

Answer 3

where do you see the exception? have you tried this?

    List<Integer[]> list = new ArrayList<Integer[]>(3);
    Integer[] a1 = {1,3};
    Integer[] a2 = {4,5};
    Integer[] a3 = {1,3,7};

    list.add(a1);
    list.add(a2);
    list.add(a3);

    Integer result = list.get(0)[1];

There aren't any exception. The arraylist have three elementes because you have three elemente (a1,a2,a3),

Answer 4

You have List<Integer[]> l = new ArrayList<Integer[]>(3);

if you want the second element of the first index:

l.get(0)[1].