List set Introduction & common methods

java.util.list Interface extends Collection Interface .

list Interface features ：

1.        1. Ordered interface , The order in which the elements are stored is the same as the order in which they are taken out （ Storage 123 Take out 123）
2.        2. There is an index , Contains some indexed methods
3.        3. Allows the storage of duplicate elements

Common methods are ：

List Method with index in interface （ specific ）
      --public void add(int index,E element): Will specify the element , Add to the specified location in the collection
      --public E get(int index): Returns the specified element in the collection
      --public E remove(int index): Remove the element at the specified location in the list , What is returned is the removed element ,
      --public E set(int index,E element): Replace the element at the specified location in the collection with the specified element , Returns the pre update element of the value ,
      Be careful ：
      When operating the index, be sure to prevent the index from crossing the boundary ;

Demonstration of examples ：

public class Demo01LIst {
    public static void main(String[] args) {
        // Create a list A collection of objects , polymorphic 
        ArrayList<String>  list=new ArrayList<>();
        list.add("a");
        list.add("b");
        list.add("c");
        list.add("d");
        list.add("e");
        // Print set 
        System.out.println(list);
        // --public void add(int index,E element): Will specify the element , Add to the specified location in the collection 
        // stay c and d Add an element between 
        list.add(2,"bbb");
        System.out.println(list);
        //-public E get(int index): Returns the specified element in the collection 
        String s = list.get(4);
        System.out.println(s);
        //   --public E remove(int index): Remove the element at the specified location in the list , What is returned is the removed element ,
        String remove = list.remove(1);
        System.out.println(" What was removed was ："+remove);
//        --public E set(int index,E element): Replace the element at the specified location in the collection with the specified element , Returns the pre update element of the value ,
        String set = list.set(0, "aaa");
        System.out.println(" The change is ："+set);

        //list There are three ways to traverse sets 
        for (int i = 0; i < list.size(); i++) {
            String s1 = list.get(i);
            System.out.println(s1);
        }
        // Use iterators to traverse 
        Iterator<String> it = list.iterator();
        while(it.hasNext()){
            String next = it.next();
            System.out.println(next);
        }
        // Use enhancements for Loop traversal 
        for (String l :list) {
            System.out.println(l);

        }
    }
}

Results, ：

[a, b, c, d, e]
[a, b, bbb, c, d, e]
d
 What was removed was ：b
 The change is ：a
aaa
bbb
c
d
e
aaa
bbb
c
d
e
aaa
bbb
c
d
e