错在何处
import java.util.*;
public class Grade{
  public static void main(String args[]){
  Scanner in=new Scanner(System.in);
  System.out.println("请输入等级：");
  String grade=in.nextLine();
  switch(grade){
  case"A":System.out.println(grade+"is 85~100");
  break;
  case"B":System.out.println(grade+"is 70~84");
  break;
  case"C":System.out.println(grade+"is 60~69");
  break;
  case"D":System.out.println(grade+"is<60") ;
  break;
  default:System.out.println("input error");
  }  
  }
  }
错在何处。。

------解决方案--------------------
case"A" jdk1.7貌似才支持String可以修改case 'A'
------解决方案--------------------
貌似没错
------解决方案--------------------

Java code

import java.util.*;

public class Grade {
    public static void main(String args[]) {
        Scanner in = new Scanner(System.in);
        System.out.println("请输入等级：");
        String grade = in.nextLine();
        switch (grade.charAt(0)) {
        case 'A':
            System.out.println(grade + "is 85~100");
            break;
        case 'B':
            System.out.println(grade + "is 70~84");
            break;
        case 'C':
            System.out.println(grade + "is 60~69");
            break;
        case 'D':
            System.out.println(grade + "is<60");
            break;
        default:
            System.out.println("input error");
        }
    }
}