package top.qaqaq.java.P702;


import org.junit.jupiter.api.Test;

import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.*;

/**
 * @author RichieZhang
 * @create 2022-11-05 下午 12:50
 */
public class Java9Test1 {

    //java9新特性八：集合工厂方法：创建只读集合
    //java8中的写法：

    @Test
    public void test1() {
        List<String> namesList = new ArrayList<>();
        namesList.add("Joe");
        namesList.add("Bob");
        namesList.add("Bill");
        //返回的namelist是一个只读的集合
        namesList = Collections.unmodifiableList(namesList);

        namesList.add("Tom");
        System.out.println(namesList);
    }

    @Test
    public void test2() {
        List<String> list = Collections.unmodifiableList(Arrays.asList("a", "b", "c"));
        Set<String> set = Collections.unmodifiableSet(new HashSet<>(Arrays.asList("a", "b", "c")));
        // 如下操作不适用于jdk 8 及之前版本,适用于jdk 9
        Map<String, Integer> map = Collections.unmodifiableMap(new HashMap<>() {
            {
                put("a", 1);
                put("b", 2);
                put("c", 3);
            }
        });
        map.forEach((k, v) -> System.out.println(k + ":" + v));
    }

    @Test
    public void test3() {
        //此时得到的集合list也是一个只读集合。
        List<Integer> list = Arrays.asList(1, 2, 3, 4, 5);
        //报异常
        list.add(6);
    }

    //java9新特性八：集合工厂方法：创建只读集合
    @Test
    public void test4() {
        List<Integer> list1 = List.of(1, 2, 3, 4, 5);
        //不能添加
//        list1.add(6);

        System.out.println(list1);

        Set<Integer> set1 = Set.of(23, 3, 54, 65, 43, 76, 87, 34, 46);
        //不能添加
//        set1.add(4);
        System.out.println(set1);

        Map<String, Integer> map1 = Map.of("Tom", 23, "Jerry", 54, "HanMeimei", 12);
        //不能添加
//        map1.put("LiLei",34);
        System.out.println(map1);

        Map<String, Integer> map2 = Map.ofEntries(Map.entry("Tom", 34), Map.entry("Jerry", 21));
//        map2.put("LiLei",34);
        System.out.println(map2);
    }

    //java9新特性九：InputStream的新方法: tranferTo()
    @Test
    public void test5() {
        ClassLoader cl = this.getClass().getClassLoader();
        try (InputStream is = cl.getResourceAsStream("hello.txt");
             OutputStream os = new FileOutputStream("src\\hello1.txt")) {
            is.transferTo(os); // 把输入流中的所有数据直接自动地复制到输出流中
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}