public class MapDemo {
    public static void main(String[] args) {
        //創(chuàng)建 map對(duì)象
        HashMap<String, String>  map = new HashMap<String, String>();
        //添加元素到集合
        map.put("青菜", "蘿卜");
        map.put("紅花", "綠葉");
        map.put("美景", "佳人");
        System.out.println(map);

        //String remove(String key)
        System.out.println(map.remove("青菜"));
        System.out.println(map);

        // 查看 紅花的鍵值是啥
        System.out.println(map.get("紅花"));
        System.out.println(map.get("青菜"));    
    }
}

public class MapDemo01 {
    public static void main(String[] args) {
        //創(chuàng)建Map集合對(duì)象 
        HashMap<String, String> map = new HashMap<String,String>();
        //添加元素到集合 
        map.put("青菜", "蘿卜");
        map.put("紅花", "綠葉");
        map.put("美景", "佳人");
        //獲取所有的鍵  獲取鍵集
        Set<String> keys = map.keySet();
        // 遍歷鍵集 得到 每一個(gè)鍵
        for (String key : keys) {
          	//key  就是鍵
            //獲取對(duì)應(yīng)值
            String value = map.get(key);
            System.out.println(key+"的CP是："+value);
        }  
    }
}

public class MapDemo02 {
    public static void main(String[] args) {
        // 創(chuàng)建Map集合對(duì)象 
        HashMap<String, String> map = new HashMap<String,String>();
        // 添加元素到集合 
        map.put("青菜", "蘿卜");
        map.put("紅花", "綠葉");
        map.put("美景", "佳人");

        // 獲取 所有的 entry對(duì)象  entrySet
        Set<Entry<String,String>> entrySet = map.entrySet();

        // 遍歷得到每一個(gè)entry對(duì)象
        for (Entry<String, String> entry : entrySet) {
           	// 解析 
            String key = entry.getKey();
            String value = entry.getValue();  
            System.out.println(key+"的CP是:"+value);
        }
    }
}

public class Student {
    private String name;
    private int age;
    public Student() {
    }
    public Student(String name, int age) {
        this.name = name;
        this.age = age;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }
    public void setAge(int age) {
        this.age = age;
    }
    @Override
    public boolean equals(Object o) {
        if (this == o)
            return true;
        if (o == null || getClass() != o.getClass())
            return false;
        Student student = (Student) o;
        return age == student.age && Objects.equals(name, student.name);
    }
    @Override
    public int hashCode() {
        return Objects.hash(name, age);
    }
}

public class HashMapTest {
    public static void main(String[] args) {
        //1,創(chuàng)建Hashmap集合對(duì)象。
        Map<Student,String>map = new HashMap<Student,String>();
        //2,添加元素。
        map.put(newStudent("lisi",28), "上海");
        map.put(newStudent("wangwu",22), "北京");
        map.put(newStudent("zhaoliu",24), "成都");
        map.put(newStudent("zhouqi",25), "廣州");
        map.put(newStudent("wangwu",22), "南京");
        //3,取出元素。鍵找值方式
        Set<Student>keySet = map.keySet();
        for(Student key: keySet){
            Stringvalue = map.get(key);
            System.out.println(key.toString()+"....."+value);
        }
    }
}

public class LinkedHashMapDemo {
    public static void main(String[] args) {
        LinkedHashMap<String, String> map = new LinkedHashMap<String, String>();
        map.put("青菜", "蘿卜");
        map.put("紅花", "綠葉");
        map.put("美景", "佳人");
        Set<Entry<String, String>> entrySet = map.entrySet();
        for (Entry<String, String> entry : entrySet) {
            System.out.println(entry.getKey() + "  " + entry.getValue());
        }
    }
}

public class MapTest {
public static void main(String[] args) {
        //友情提示
        System.out.println("請(qǐng)錄入一個(gè)字符串:");
        String line = new Scanner(System.in).nextLine();
        // 定義 每個(gè)字符出現(xiàn)次數(shù)的方法
        findChar(line);
    }
    private static void findChar(String line) {
        //1:創(chuàng)建一個(gè)集合 存儲(chǔ)  字符 以及其出現(xiàn)的次數(shù)
        HashMap<Character, Integer> map = new HashMap<Character, Integer>();
        //2:遍歷字符串
        for (int i = 0; i < line.length(); i++) {
            char c = line.charAt(i);
            //判斷 該字符 是否在鍵集中
            if (!map.containsKey(c)) {//說明這個(gè)字符沒有出現(xiàn)過
                //那就是第一次
                map.put(c, 1);
            } else {
                //先獲取之前的次數(shù)
                Integer count = map.get(c);
                //count++;
                //再次存入  更新
                map.put(c, ++count);
            }
        }
        System.out.println(map);
    }
}

public class Demo01 {
    public static void main(String[] args) {
        List<String> list = new ArrayList<>();
        list.add("abc");
        list.add("def");
        list.add("ghi");
        System.out.println(list);
    }
}

public class HelloJDK9 {  
    public static void main(String[] args) {  
        Set<String> str1=Set.of("a","b","c");  
        //str1.add("c");這里編譯的時(shí)候不會(huì)錯(cuò)，但是執(zhí)行的時(shí)候會(huì)報(bào)錯(cuò)，因?yàn)槭遣豢勺兊募? 
        System.out.println(str1);  
        Map<String,Integer> str2=Map.of("a",1,"b",2);  
        System.out.println(str2);  
        List<String> str3=List.of("a","b");  
        System.out.println(str3);  
    }  
}