Collection与Collections

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package com.itheima.testinterfacess;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.List;

public class AddingGroups {

public static void main(String[] args) {    Integer [] moreInts = {6,7,8,9,10};     /**       public static <T> List<T> asList(T... a) {            return new ArrayList<>(a);       }     */    List<Integer> asList = Arrays.asList(moreInts);    //ArrayList()有一个含参构造方法：public ArrayList(Collection<? extends E> c)里面含有Collection的实现类就可以了    Collection<Integer> collection = new ArrayList<Integer>(Arrays.asList(1,2,3,4,5));    //把整个集合添加进来    collection.addAll(asList);    for (Integer integer : collection) {        System.out.print(integer);    }    System.out.println("------------------------------------------");    Collections.addAll(collection, 11,12,13,14,15);    for (Integer integer : collection) {        System.out.print(integer);    }    System.out.println("------------------------------------------");    Collections.addAll(collection, moreInts);    for (Integer integer : collection) {        System.out.print(integer);    }}

}

输出结果：
12345678910——————————————
123456789101112131415——————————————
123456789101112131415678910

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