java - 如何更改 DrJava 中的源代码级别

Question

我尝试在静态方法中运行 switch 函数，但不断收到此错误:

File: C:\Users\Darien Springer\Documents\Java\DaysInMonth.java  [line: 6]

Error: Cannot switch on a value of type String for source level below 1.7. 

Only convertible int values or enum variables are permitted

我查阅了几份指南，但似乎没有一个说明如何将源级别更改为 1.7 以上。当我查看设置时，它显示 DrJava 正在 Java 版本 1.8 上运行，所以我对问题所在感到困惑。这是我的类文件:

import java.util.Scanner;  
public class DaysInMonth { 

   public static void daysInaMonth (int year_number, String month_name) {
      if(year_number % 4 != 0 || month_name != "February") {
         switch(month_name) {
            case "January":
            case "March":
            case "May":
            case "July":
            case "August":
            case "October":
            case "December":
                System.out.print("31");
               break;
            case "April":
            case "June":
            case "September":
            case "November":
                System.out.print("30");
               break;
            case "February":
               System.out.print("28");
               break;
            default:
               System.out.print("Please input ");
               break;
         }  
      }
      else {
           System.out.print("29");
      }


   }

Answer 1

您必须从Oracle网页下载并安装新的jdk版本。