java-14习题

 .使用TreeSet集合生成一个不重复随机数组，该数组包含10个100以内的随机整数。输出该随机数组。 

 import java.util.Iterator;
 import java.util.TreeSet;

 public class Test {
     public static void main(String[] args) {
         int x;
         int arr []=new int [];
         TreeSet<Integer> set =new TreeSet<Integer>();

         int d=;
         while(d<){
             x=(int)(Math.random()*);
             if(set.add(x))//TreeSet是去重复的集合，集合中没有的返回true
                 d++;
         }
         /*
          while(set.size()<10){
             x=(int)(Math.random()*100);
            set.add(x);
         }
          */
         int i=;
         Iterator<Integer>it=set.iterator();
         while(it.hasNext()){
             int t=it.next();
             arr[i]=t;
             i++;
         }
         for(i=;i<=;i++)
             System.out.print(arr[i]+" ");
     }
 }

 .创建一个Student类，使用比较器Comparator，根据学号进行对象排序。

 import java.util.Comparator;
 import java.util.Iterator;
 import java.util.TreeSet;
 class Student {
     private String name;
     private String id;
     public Student(){
     }
     public Student(String name,String id){
         this.name=name;
         this.id=id;
     }
     public String getName() {
         return name;
     }
     public String getId() {
         return id;
     }
 }
 class DescSort implements Comparator<Student> {

     public int compare(Student s1, Student s2) {
         if(s1.getId().compareTo(s2.getId())>)
             return -;
         else if(s1.getId().compareTo(s2.getId())<)
             return ;
         else return ;
     }
 }
 public class Test {
     public static void main(String[] args)   {
     Comparator<Student> comp=new DescSort();
     TreeSet<Student> t=new TreeSet<Student>(comp);
     t.add(new Student("小赵",""));
     t.add(new Student("小王",""));
     t.add(new Student("小明",""));
     t.add(new Student("小红",""));
     t.add(new Student("小李",""));
     Iterator<Student>it=t.iterator();
     while(it.hasNext()){
         Student stu=it.next();
         System.out.println(stu.getName()+"的学号是"+stu.getId());
     }
 }
 }

输出结果：