关于#for#的问题，如何解决？

Question

• <input type="checkbox" disabled="" /> java

     HashMap<String,HashMap<String,Integer>>studentname=new HashMap<>();
    HashMap<String,Integer>mark1=new HashMap<>();
    mark1.put("语文", 11);
    mark1.put("数学", 22);
    mark1.put("英语", 33);
    HashMap<String,Integer>mark2=new HashMap<>();
    mark2.put("语文", 100);
    mark2.put("数学", 100);
    mark2.put("物理", 100);
    HashMap<String,Integer>mark3=new HashMap<>();
    mark3.put("语文", 80);
    mark3.put("物理", 40);
    mark3.put("英语", 60);
    studentname.put("珈乐", mark1);
    studentname.put("贝拉", mark2);
    studentname.put("嘉然", mark3);
     for (String student : studentname.keySet()) {//遍历大的哈希map
         System.out.print("\n"+student);
            for (String course: studentname.get(student).keySet()) {//遍历小的哈希map     
            }
             }
     System.out.print("请输入您想查询的科目");
     Scanner in=new Scanner(System.in);
     String b=in.next();
     int x=0;
     String g[]={"语文","数学","英语","物理"};
     for(String student:studentname.keySet()) {//遍历大哈希map里的学生名字
         for(String course:studentname.get(student).keySet()) {//遍历小哈希map里面科目的名字
             if(course==b)
             {
              System.out.print(student);
              System.out.print(studentname.get(student).get(b)+"\n");
             }     
         }
          }
  

Answer 1

string 比较 用 equals