java - 已声明时找不到符号

Question

请有人帮助我解决此错误:

import java.util.*;
class Cinema
{
    public static void main(String args[])
    {
        Scanner sc = new Scanner(System.in);
        int cat;
        System.out.println("Choose your category : \n 1)Premium - Rs.150 \n 2)Gold - Rs.200 \n 3)Business Class - Rs.400");
        cat = sc.nextInt();
        switch(cat)
        {
            case 1:
            {
                System.out.println("You have selected Premium");
                int t = 150;   /* VARIABLE DECLARED */
                break;
            }
            case 2:
            {
                System.out.println("You have selected Gold");
                int t = 200;  /* VARIABLE DECLARED */
                break;
            }
            case 3:
            {
                System.out.println("You have selected Business Class");
                int t = 400;  /* VARIABLE DECLARED */
                break;
            }
            default:
            System.out.println("Invalid Option");
            break;
        }
        Scanner num = new Scanner(System.in);
        int n, amt;
        System.out.println("Choose number of tickets");
        n = num.nextInt();
        amt = t * n;      /* ERROR : cannot find symbol - variable t */
        System.out.println("You are buying " +n+ " tickets of " +cat+ " for Rs." +amt);
    }
}

我已经在 case block 中声明了变量 t 但它找不到它。我查看了许多类似问题的答案，但似乎无法解决

Answer 1

您需要在 switch block 之前声明变量，以便可以在 switch block 之外访问它......请参阅下面的内容

import java.util.*;
public class Cinema {
public static void main(String args[])
{
    Scanner sc = new Scanner(System.in);
    int cat;
    System.out.println("Choose your category : \n 1)Premium - Rs.150 \n 2)Gold - Rs.200 \n 3)Business Class - Rs.400");
    cat = sc.nextInt();

    int t = 0;
    switch(cat)
    {
        case 1:
        {
            System.out.println("You have selected Premium");
             t = 150;   /* VARIABLE DECLARED */
            break;
        }
        case 2:
        {
            System.out.println("You have selected Gold");
            t = 200;  /* VARIABLE DECLARED */
            break;
        }
        case 3:
        {
            System.out.println("You have selected Business Class");
            t = 400;  /* VARIABLE DECLARED */
            break;
        }
        default:
            System.out.println("Invalid Option");
            break;
    }
    Scanner num = new Scanner(System.in);
    int n, amt;
    System.out.println("Choose number of tickets");
    n = num.nextInt();
    amt = t * n;      /* ERROR : cannot find symbol - variable t */
    System.out.println("You are buying " +n+ " tickets of " +cat+ " for Rs." +amt);
}
}