java - 变量 'result' 可能尚未初始化

Question

public class MonthName {
  public static String month_name(int month) {
    String result;

    if (month == 1) {
      result = "January";
    } else if (month == 2) {
      result = "February";
    } else if (month == 3) {
      result = "February";
    } else if (month == 4) {
      result = "February";
    } else if (month == 5) {
      result = "February";
    } else if (month == 6) {
      result = "February";
    } else if (month == 7) {
      result = "February";
    } else if (month == 8) {
      result = "February";
    } else if (month == 9) {
      result = "February";
    } else if (month == 10) {
      result = "February";
    } else if (month == 11) {
      result = "February";
    } else if (month == 12) {
      result = "February";
    }

    return result;
  }


  public static void main(String[] args) {
    System.out.println("Month 1: " + month_name(1));
    System.out.println("Month 2: " + month_name(2));
    System.out.println("Month 3: " + month_name(3));
    System.out.println("Month 4: " + month_name(4));
    System.out.println("Month 5: " + month_name(5));
    System.out.println("Month 6: " + month_name(6));
    System.out.println("Month 7: " + month_name(7));
    System.out.println("Month 8: " + month_name(8));
    System.out.println("Month 9: " + month_name(9));
    System.out.println("Month 10: " + month_name(10));
    System.out.println("Month 11: " + month_name(11));
    System.out.println("Month 12: " + month_name(12));
    System.out.println("Month 43: " + month_name(43));
  }
}

所以我已经在结果中声明了相关字符串的值，但它仍然说我的变量“结果”可能尚未初始化。

我正在尝试实现类似于 this 的输出.任何人都可以帮助我吗？谢谢!

Answer 1

好吧，如果您的变量月份可能为空或<1 或>12，就会发生这种情况。您可以通过简单地删除 if-else 树中的最后一个 if 来解决这个问题，例如:

public class MonthName {
  public static String month_name(int month) {
    String result = "";

    if (month == 1) {
      result = "January";
    } else if (month == 2) {
      result = "February";
    } else if (month == 3) {
      result = "February";
    } else if (month == 4) {
      result = "February";
    } else if (month == 5) {
      result = "February";
    } else if (month == 6) {
      result = "February";
    } else if (month == 7) {
      result = "February";
    } else if (month == 8) {
      result = "February";
    } else if (month == 9) {
      result = "February";
    } else if (month == 10) {
      result = "February";
    } else if (month == 11) {
      result = "February";
    } else {
      result = "February";
    }

    return result;
  }


  public static void main(String[] args) {
    System.out.println("Month 1: " + month_name(1));
    System.out.println("Month 2: " + month_name(2));
    System.out.println("Month 3: " + month_name(3));
    System.out.println("Month 4: " + month_name(4));
    System.out.println("Month 5: " + month_name(5));
    System.out.println("Month 6: " + month_name(6));
    System.out.println("Month 7: " + month_name(7));
    System.out.println("Month 8: " + month_name(8));
    System.out.println("Month 9: " + month_name(9));
    System.out.println("Month 10: " + month_name(10));
    System.out.println("Month 11: " + month_name(11));
    System.out.println("Month 12: " + month_name(12));
    System.out.println("Month 43: " + month_name(43));
  }
}

这意味着您的变量必须介于 1 和 12 之间，否则您应该抛出异常。但无论如何，我不会一直使用那些 if-else 树。无论如何冗余太多。

这个这个代替:

switch (month) {
case 1:  result = "January";
         break;
case 2:  result = "February";
         break;
case 3:  result = "March";
         break;
case 4:  result = "April";
         break;
case 5:  result = "May";
         break;
case 6:  result = "June";
         break;
case 7:  result = "July";
         break;
case 8:  result = "August";
         break;
case 9:  result = "September";
         break;
case 10: result = "October";
         break;
case 11: result = "November";
         break;
case 12: result = "December";
         break;
default: result = "Invalid month";
         break;
}