集合框架之堆栈

堆栈 Stack：表示一个先进后出的数据结构

// list集合
	private LinkedList lst = new LinkedList();

	
	public void push(Object obj) {
		lst.addFirst(obj);
	}

	
	public Object pop() {
		Object first = lst.getFirst();
		lst.removeFirst();
		return first;
	}

	
	public int size() {
		return lst.size();
	}

	public static void main(String[] args) {
		// 初始化
		MyStack stack = new MyStack();
		// 压栈
		stack.push("a");
		stack.push("b");
		stack.push("c");
		stack.push("d");
		stack.push("e");
		while (stack.size() != 0) {
			Object val = stack.pop();
			System.out.println(val);
		}
	}

遍历(2种)
     foreach 

		Set set = new HashSet<>();
		set.add(new Student(1,"sw",100f));
		set.add(new Student(2,"daw",50f));
		set.add(new Student(3,"dsa",30f));
for (Student student : set) {
			System.out.println(student);
		}
		

迭代器

Set set = new HashSet<>();
		set.add(new Student(1,"sw",100f));
		set.add(new Student(2,"daw",50f));
		set.add(new Student(3,"dsa",30f));

//迭代器
		Iterator it = set.iterator();
		//循环遍历
		while(it.hasNext()) {
			System.out.println(it.next());
		}

 TreeSet：根据某种(规则)对里面的元素进行排序

	
		Set set = new TreeSet<>();
		set.add(new Student(1,"sw",100f));
		set.add(new Student(2,"daw",50f));
		set.add(new Student(3,"dsa",30f));
		
		set.forEach(System.out::println);

实体类代码

@Override
	public int compareTo(Student o) {
		// 比较着大于被比较着，返回1
		// 比较着等于被比较着，返回0
		// 比较着小于被比较着，返回-1
//		if(this.getSid()>o.getSid())
//			return 1;
//		else {
//			if(this.getSid()==o.getSid())
//				return 0;
//			else
//				return -1;
//	}
		return this.getSid()-o.getSid();
	}

 打//也能用只是简化了