HashMap获取输入的排序值+将最高值打印为字符串和整数

Question

HashMap <String,Integer> student = new HashMap <String,Integer> (); 
        System.out.println("Enter a number of students: ");
        int numberOfStudents = sc.nextInt();

        String a ="";

        Integer b = 0;

          for(int i=0; i<numberOfStudents; i++){
            System.out.println("Enter a student's name");
              a=sc.next();
                  System.out.println("Enter the student's score");
                     b=sc.nextInt();
                          student.put(a, b);

 }
   student.entrySet()
  .stream()
  .sorted(HashMap.Entry.<String, Integer>comparingByKey())
  .forEach(System.out::println);
        if(b>4)
    System.out.println("The best student is "+student.get(a));/*Here "a" is a string,isn't it? Firstly ,
I tried to get the values of both String and Integer by writing student.get(a,b); But the program
throws Exceptions saying "no suitable method found for get(String , Integer)".*/

以下是输出：

Enter a number of students: 
2
Enter a student's name
N
Enter the student's score
4
Enter a student's name
d
Enter the student's score
5
N=4
d=5
The best student is 5

为什么程序将“a”（字符串）显示为整数，而将a切换为b（整数）时显示为空？而我如何才能最终显示最好的学生的名字和他的分数呢？

Answer 1

在hashmap中，第一个值是键，第二个值与键相关联。

HashMap <String,Integer> student = new HashMap <String,Integer> (); 

这里字符串是关键字，这意味着HashMap是根据String排序的，而不是根据需要的integer。尝试使用以下方法,

HashMap <Integer, String> student = new HashMap <String,Integer> (); 

student.get(a)给出了与键a相对应的值，这就是在您的示例中获得integer输出的原因。

String key = entry.getKey();


String value = entry.getValue();