java 项目 - 区域

Question

我正在开发一个项目，您在扫描仪中输入州的缩写，然后程序会告诉您该州位于美国的哪个地区。我认为我的大部分代码都是正确的，但我有以前从未使用过 switch。

我已经将我的工作改进为一个错误，即我的第一个代码块(switch 部分)中缺少 return 语句。我不知道是否有任何其他代码影响它，所以我只是将其中的大部分内容发布在这里。提前致谢。

import java.util.Scanner;
public class Regions {
  public static String getRegion (String stateName){
    String region = "";
    switch(stateName){
      case "ME":
      case "VT":
      case "NH":
      case "MA":
      case "CT":
      case "RI":
      region = "New England";
      break;
      case "NY":
      case "NJ":
      case "DE":
      case "MD":
      case "VA":
      case "NC":
      case "SC":
      region = "Atlantic";
      break;
      case "GA":
      case "FL":
      case "MS":
      case "AL":
      case "LA":
      case "TN":
      region = "Southeast";
      break; 
      case "PA":
      case "OH":
      case "MI":
      case "IN":
      case "IL":
      case "WI":
      case "MN":
      case "KY":
      case "WV":
      case "IA":
      region = "Midwest";
      break;
      case "ND":
      case "SD":
      case "KS":
      case "NE":
      case "MO":
      region = "Great Plains";
      break;

    }
  }

  public static void main (String[]args){
     Scanner s = new Scanner(System.in);
     System.out.println("Enter a two-letter state abbreviation:");
     String stateName = s.nextLine();
     String region = getRegion(stateName);
     System.out.print("The state " + stateName);
     if (region == "New England"){
       System.out.print(" is in the New England region!");
     }
     else if (region == "Atlantic") {
       System.out.print(" is in the Atlantic region!");
     }
     else if (region == "Southeast") {
       System.out.print(" is in the Southeast region!");
            }
     else if (region == "Midwest") {
       System.out.print(" is in the Midwest region!");
            }
     else if (region == "Great Plains") {
       System.out.print(" is in the Great Plains region!");
            }
     else {
         System.out.println ("That's not a state.");
       }
     }

  }`

Answer 1

第一个问题:getRegion()
中缺少返回值只需添加

return region;

添加该方法的末尾。

第二个问题:用==而不是equals比较字符串
在您的 main 中替换所有

if (region == "..."){

与

if (region.equals("...")){