java - Case 表达式必须是常量表达式

Question

我是 Java 新手，我一直收到 case 表达式必须是常量表达式错误，有人可以帮忙吗？这是我的代码:

import java.util.Scanner;

public class IDlookup {
public void IDlookup(){
    String Stone = "ID - 1";
    String Granite = "ID - 1:1";
    //System.out.println("Hai"); //TESTER
    System.out.println("Please enter the block/item name here");
    Scanner IDselectO = new Scanner(System.in);
    String IDselect;
    IDselect = IDselectO.next();

    switch(IDselect){
    case Stone:
        System.out.println(Stone);
        break;
    case Granite:
        System.out.println(Granite);
    }



}

}

Answer 1

错误非常明显，将 Stone 和 Granite 声明为常量

public class IDlookup {
    private final static String STONE = "ID - 1";
    private final static String GRANITE = "ID - 1:1";
        ...
}