public class SetDemo_01 {
    public static void main(String[] args) {
        Set<String> set = new HashSet<>();
 
        //添加元素
        set.add("Hello");
        set.add("World");
        set.add("Java");
        set.add("Hello");//Set不包含重復元素的集合，（相同的，只輸出一個）
 
        //Set沒有索引、只能通過迭代器或增強for循環(huán)遍歷且元素存取無序
        //迭代器遍歷
        Iterator<String> it = set.iterator();
        while(it.hasNext()) {
            String s = it.next();
            System.out.println(s);
        }
 
        //增強for
        for (String s : set) {
            System.out.println(s);
        }
    }
}

public class HashSetDemo_01 {
    public static void main(String[] args) {
        //創(chuàng)建集合對象
        HashSet<String> hs = new HashSet<>();
 
        //添加元素
        hs.add("Hello");
        hs.add("World");
        hs.add("Java");
        hs.add("Java");//由于是Set集合，所以是不包含重復元素的集合.相同的元素，只輸出一個
 
        //沒有帶索引的方法，所以不能使用普通for循環(huán)遍歷
        //迭代器方式
        Iterator<String> it = hs.iterator();
        while (it.hasNext()) {
            String s = it.next();
            System.out.println(s);
        }
        System.out.println("----------------");
 
        //增強for
        for (String s : hs) {
            System.out.println(s);
        }
    }
}

public class LinkedHashSetDemo {
    public static void main(String[] args) {
        //創(chuàng)建LinkedHashSet集合對象
        LinkedHashSet<String> lhs = new LinkedHashSet<>();
 
        lhs.add("Hello");
        lhs.add("World");
        lhs.add("Java");
 
        //由哈希表保證元素唯一，也就是說沒有重復的元素
        lhs.add("Java");
 
        /*哈希表和鏈表實現的Set接口，具有可預測的迭代次序
        由鏈表保證元素有序，也就是說元素的存儲和取出順序是一致的*/
        //遍歷集合
        for (String s : lhs) {
            System.out.println(s);
        }
    }
}

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;
    }
}

public class TreeSetDemo {
    public static void main(String[] args) {
        //創(chuàng)建集合對象
        TreeSet<Student> ts = new TreeSet<Student>(new Comparator<Student>() {
            @Override
            public int compare(Student s1, Student s2) {
                //this.age - s.age
                //s1,s2
                int num = s1.getAge() - s2.getAge();
                int num2 = num == 0 ? s1.getName().compareTo(s2.getName()) : num;
                return num2;
            }
        });
 
        //創(chuàng)建學生對象
        Student s1 = new Student("xishi", 29);
        Student s2 = new Student("wangzhaojun", 28);
        Student s3 = new Student("diaochan", 30);
        Student s4 = new Student("yangyuhuan", 33);
 
        Student s5 = new Student("linqingxia",33);
        Student s6 = new Student("linqingxia",33);
 
        //把學生添加到集合
        ts.add(s1);
        ts.add(s2);
        ts.add(s3);
        ts.add(s4);
        ts.add(s5);
        ts.add(s6);
 
        //遍歷集合
        for (Student s : ts) {
            System.out.println(s.getName() + "," + s.getAge());
        }
    }
}