mcrypt_encrypt和mcrypt_decrypt是用来进行字符串加密解密的加油，希望课程对你有帮助。

public class SetTest {

	public Set<Course> Set_CourseToSelect;
	public Course c;
	public Course e;
	public Course[] cc;
	public Course[] ee;
	public SetTest()
	{
		Set_CourseToSelect=new  HashSet<Course>();
	}	
	public void Add()
	{
		//1.add():
		c=new Course(1,"java");
		e=c;
		Set_CourseToSelect.add(c);
		//2.addAll():
		cc=new Course[]{new Course(2,"C"),new Course(3,"C#")};
		ee=cc;
		Set_CourseToSelect.addAll(Arrays.asList(cc));
	}
	public void Remove()
	{
		//3.remove():
		//Set_CourseToSelect.remove(e);
		//4.removeAll():
		Set_CourseToSelect.removeAll(Arrays.asList(ee));
	}
	public void Get()
	{
		System.out.println("-----------------------");
		for(Course c:Set_CourseToSelect)
		{
			System.out.println(c.id+":"+c.name);
		}
		
	}
	/**
	 * @param args
	 */
	public static void main(String[] args) 
	{
	  // TODO Auto-generated method stub
             SetTest st=new SetTest();
             st.Add();
             st.Remove();
             st.Get();
         }
  }