【ThinkingInJava】48、java中Collection的各种操作

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/*** 书本:《Thinking In Java》* 功能:java中Collection的各种操作* 文件:CollectionMethods.java* 时间:2015年5月1日10:08:16* 作者:cutter_point*/package Lesson17Containers;import java.util.List;import java.util.ArrayList;import java.util.Collection;import java.util.Collections;import net.mindview.util.Countries;import static net.mindview.util.Print.*;public class CollectionMethods{public static void main(String[] args){Collection<String> c = new ArrayList<String>();c.addAll(Countries.names(6));c.add("ten");c.add("eleven");print(c);Object[] array = c.toArray();//吧c化为Object类型的数组String[] str = c.toArray(new String[0]);//这里安字典的排序排序了print("Collections.max(c) = " + Collections.max(c));//排序最大的print("Collections.min(c) = " + Collections.min(c));//排序最小的print("-------------------------------------------------------");Collection<String> c2 = new ArrayList<String>();c2.addAll(Countries.names(6));c.addAll(c2);//吧c2的值尾随到c中print(c);print("-------------------------------------------------------");//我们删除几个值试一试c.remove(Countries.DATA[0][0]);//只要发生了删除就返回true，不管集合里面还有没有重复的    print(c);    c.remove(Countries.DATA[1][0]);    print(c);    print("-------------------------------------------------------");    c.removeAll(c2);//去除所有的c2中有的元素，有多少去多少    print(c);    c.addAll(c2);    print(c);    print("-------------------------------------------------------");    //contains的作用就是看一看容器中是否包含有这个val元素    String val = Countries.DATA[3][0];    print("c.contains(" + val  + ") = " + c.contains(val));    //极端一点，可以搞一个集合来看看是否包含有    print("c.containsAll(c2) = " + c.containsAll(c2));//完全包含    Collection<String> c3 = ((List<String>)c).subList(3, 5);//吧c中排在第4和第5的元素拿出来[ten, eleven, ALGERIA, ANGOLA, BENIN, BOTSWANA, BURKINA FASO, BURUNDI]    print("-------------------------------------------------------");    //我们求一下交集    c2.retainAll(c3);//c2和c3的交集，保存到c2中    print(c2);    print("-------------------------------------------------------");    //吧c2中的c3部分去掉,c2现在是[ANGOLA, BENIN]    c2.removeAll(c3);    print("c2.isEmpty() = " +  c2.isEmpty());    print("-------------------------------------------------------");    //当前c是：[ten, eleven, ALGERIA, ANGOLA, BENIN, BOTSWANA, BURKINA FASO, BURUNDI]    c = new ArrayList<String>();//重新创建,前面那个c就已经丢失了    c.addAll(Countries.names(6));    print(c);    c.clear(); // 清空所有元素    print("after c.clear():" + c);    }}

输出：

[ALGERIA, ANGOLA, BENIN, BOTSWANA, BURKINA FASO, BURUNDI, ten, eleven] obj1
Collections.max(c) = ten obj1
Collections.min(c) = ALGERIA obj1
------------------------------------------------------- obj1
[ALGERIA, ANGOLA, BENIN, BOTSWANA, BURKINA FASO, BURUNDI, ten, eleven, ALGERIA, ANGOLA, BENIN, BOTSWANA, BURKINA FASO, BURUNDI] obj1
------------------------------------------------------- obj1
[ANGOLA, BENIN, BOTSWANA, BURKINA FASO, BURUNDI, ten, eleven, ALGERIA, ANGOLA, BENIN, BOTSWANA, BURKINA FASO, BURUNDI] obj1
[BENIN, BOTSWANA, BURKINA FASO, BURUNDI, ten, eleven, ALGERIA, ANGOLA, BENIN, BOTSWANA, BURKINA FASO, BURUNDI] obj1
------------------------------------------------------- obj1
[ten, eleven] obj1
[ten, eleven, ALGERIA, ANGOLA, BENIN, BOTSWANA, BURKINA FASO, BURUNDI] obj1
------------------------------------------------------- obj1
c.contains(BOTSWANA) = true obj1
c.containsAll(c2) = true obj1
------------------------------------------------------- obj1
[ANGOLA, BENIN] obj1
------------------------------------------------------- obj1
c2.isEmpty() = true obj1
------------------------------------------------------- obj1
[ALGERIA, ANGOLA, BENIN, BOTSWANA, BURKINA FASO, BURUNDI] obj1
after c.clear():[] obj1

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