谁帮我做下这道java的题呀创建checkAnswer方法实现不定项选择判分,具体要求如下：1）考生答案和正确答案相同（

public static int checkAnswer(String correctAnswer, String userAnswer)
{
int grade = 0;
int num = 0;
for (int i = 0; i < userAnswer.length(); i++)
{
// 如果用户答案某一项在正确答案中
if (correctAnswer.indexOf(userAnswer.charAt(i)) != -1)
{
num++;
}
// 如果用户答案某一项不在正确答案中（即有错误选择项）
else
{
return grade = 0;
}
}
if (num == 0)
{
grade = 0;
}
else if (num == correctAnswer.length())
{
grade = 5;
}
else
{
grade = 2;
}
return grade;
}

public static void main(String[] args)
{
String correctAnswer = "ABC";
String userAnswer = "D";
int grade = checkAnswer(correctAnswer, userAnswer);
System.out.println("本题得分 ： " + grade);
}