Java List.add（）方法

Question

Below is the method add() of Java List Interface ; if I loop through it 7 times adding i to the 0 th position like so.

for (int i = 0; i < 7; i++) {
    list.add(0, i);
}

Wouldn't it overwrite the value at that position, so I would end up with just one value of 6 in the list? Am I right, in assuming that?

Answer 1

No, if you add at a position, it shifts everything starting at that position to the right.

So if you actually did this, you should end up with the following list:

[6, 5, 4, 3, 2, 1, 0]

Read the API: http://docs.oracle.com/javase/7/docs/api/java/util/List.html#add%28int,%20E%29

Or better yet, give it an actual try.

Answer 2

Suppose we have,

mylist = ["Bashful","Awful","Jumpy","Happy"]

then,

mylist.add(2,"Doc") 

makes the ArrayList

mylist = ["Bashful","Awful","Doc","Jumpy","Happy"]

Notice that the indices of "Jumpy" and "Happy" have changed from 2 to 3, and 3 to 4, accordingly.

Answer 3

根据Java List List上的此文档，它将元素推到列表的右侧，从而向索引添加一个