java - For 循环缺少返回语句错误 - JAVA

Question

我在最后一个括号上收到缺少返回语句的错误，我不知道为什么。该方法基本上采用与学生类(class)和当前调查问题相对应的字符串。外部 if 语句与主题相对应(例如:数学、科学、英语...)。 for 循环迭代数组并将用户输入(“美国历史”)与数组列表中的字符串进行匹配。如果它们相等，则返回找到它的索引。否则，它继续 for 循环。该方法返回一个 int，但我仍然在最后一个括号上收到错误。请帮忙!

 public static int findNumber(String course, int currentQuestion) {
    String newCourse = course.toLowerCase();

    if (RateDriver.levelText.equals("math")) {
      for (int i = 0; i < RateSurvey.math.length-1;i++) {
        if (newCourse.equals(RateSurvey.math[i])) return survey[currentQuestion][i];
      }
      return 100;
    }

    else if (RateDriver.levelText.equals("science")) {
      for (int i = 0; i < RateSurvey.science.length-1;i++) {
        if (newCourse.equals(RateSurvey.science[i])) return survey[currentQuestion][i];

      }
      return 100;
    }
    else if (RateDriver.levelText.equals("english")) {
      for (int i = 0; i < RateSurvey.english.length-1;i++) {
        if (newCourse.equals(RateSurvey.english[i])) return survey[currentQuestion][i];

      }
      return 100;
    }
    else if (RateDriver.levelText.equals("social studies")) {
      for (int i = 0; i < RateSurvey.social.length-1;i++) {
        if (newCourse.equals(RateSurvey.social[i]))  return survey[currentQuestion][i];
      }
    }
    else if (RateDriver.levelText.equals("art")) {
      for (int i = 0; i < RateSurvey.art.length-1;i++) {
        if (newCourse.equals(RateSurvey.art[i])) return survey[currentQuestion][i];
      }
      return 100;
    }
    else if (RateDriver.levelText.equals("pe")) {
      for (int i = 0; i < RateSurvey.pe.length-1;i++) {
        if (newCourse.equals(RateSurvey.pe[i])) return survey[currentQuestion][i];
      }
    }
    else if (RateDriver.levelText.equals("chinese")) {
      for (int i = 0; i < RateSurvey.chinese.length-1;i++) {
        if (newCourse.equals(RateSurvey.chinese[i])) return survey[currentQuestion][i];
      }
    }
    else if (RateDriver.levelText.equals("japanese")) {
      for (int i = 0; i < RateSurvey.japanese.length-1;i++) {
        if (newCourse.equals(RateSurvey.japanese[i])) return survey[currentQuestion][i];
      }
      return 100;
    }
    else if (RateDriver.levelText.equals("french")) {
      for (int i = 0; i < RateSurvey.french.length-1;i++) {
        if (newCourse.equals(RateSurvey.french[i])) return survey[currentQuestion][i];
      }
      return 100;
    }
    else if (RateDriver.levelText.equals("spanish")) {
      for (int i = 0; i < RateSurvey.spanish.length-1;i++) {
        if (newCourse.equals(RateSurvey.spanish[i])) return survey[currentQuestion][i];
      }
      return 100;
    }
    else if (RateDriver.levelText.equals("hawaiian")) {
      for (int i = 0; i < RateSurvey.hawaiian.length-1;i++) {
        if (newCourse.equals(RateSurvey.hawaiian[i])) return survey[currentQuestion][i];
      }
      return 100;
    }
    else return 100;

  **}** // this is where I get the error

Answer 1

如果 for 循环中没有返回任何内容，则代码的某些部分不会返回任何内容，例如:

else if (RateDriver.levelText.equals("social studies")) {
  for (int i = 0; i < RateSurvey.social.length-1;i++) {
    if (newCourse.equals(RateSurvey.social[i]))  return survey[currentQuestion][i];
  }
}

因此，如果程序到达这部分代码并且最终没有返回 survey[currentQuestion][i]，那么它将跳到 if-else 链的末尾，而不是返回返回任何东西。您应该将它们更改为如下所示:

else if (RateDriver.levelText.equals("social studies")) {
  for (int i = 0; i < RateSurvey.social.length-1;i++) {
    if (newCourse.equals(RateSurvey.social[i]))  return survey[currentQuestion][i];
  }
  return 100;
}