[java data structure]—List

Definition method 1-ArrayList

Code description:

List<TreeNode> ans = new ArrayList<>();

Definition method 2-Arrays.asList

Code description

Arrays.asList(fruits) // fruits是一个数组

Method 1-add

Code description:

ans.add(root);

Method 2-contains

Code description:

boolean del = TODELETE.contains(root.val);