我们可以将用户输入与数组进行比较吗？如果是，那我做错了什么？

Question

代码的间距显示错误！

public static void switchTest() {
    String[] cars = {"TATA", "BMW", "Hero", "Honda", "Bajaj", "Yamaha"};

    System.out.println("Enter a car name:");
    Scanner sc = new Scanner(System.in);
    String userInputCar = sc.nextLine();

    switch (userInputCar == cars) {
        case "TATA":
            System.out.println("You enter TATA as a car name");
            break;
        case "BMW":
            System.out.println("You enter BMW as a car name");
            break;
        default:
            System.out.println("Ops! we are unable to get that name. Thank You:)");
    }
}

让我以正确的方式问这个问题，我们将把用户输入与给定的数组进行比较。 所以现在的问题是我们如何做到这一点？

Answer 1

我认为你需要这样做：

public static void switchTest() {
    switch ( userInputCar ) {
        case "TATA":
            System.out.println("You enter TATA as a car name");
            break;
        case "BMW":
            System.out.println("You enter BMW as a car name");
            break;
        default:
            System.out.println("Ops! we are unable to get that name. Thank You:)");
    }
}

Answer 2

A

switch

就像有很多“如果..”命令。

所以比较不在开关中：

switch (userInputCar == cars)

但是在

case

switch (userInputCar) { // Value to check

    case "TATA":   // if "TATA".equals(userInputCar)
        break;

    case "BMW":   // else if "BMW".equals(userInputCar)
        break;

    default:      // else
}

对照清单：

if(Arrays.asList(cars).contains(userInputCar)) {
   // Found
} else {
   // Not found
}

Answer 3

如果你想尝试用数组检查用户输入你可以检查下面的代码

import java.util.Scanner;
public class Main
{
    public static void main(String[] args) {
     String[] cars = {"TATA", "BMW", "Hero", "Honda", "Bajaj", "Yamaha"};
     boolean check=true;
    System.out.println("Enter a car name:");
    Scanner sc = new Scanner(System.in);
    String userInputCar = sc.nextLine();
    
    
    for(int i=0;i<cars.length;i++)
    {
        if(cars[i].equals(userInputCar))
        {
             System.out.println("You enter "+ cars[i] +" as a car name");
             check=false;
        }
      
    }
    
       if(check)
        {
          System.out.println("Ops! we are unable to get that name. Thank You");
        }
    
    }
    
    
    /*
       Here is the Output
       
       Enter a car name:
       Hero
       You enter Hero as a car name




    */
}

Answer 4

userInputCar == cars

....它不会那样工作，即使您使用 String#equals() 方法来检查正确的字符串相等性。如果有的话，它应该是这样的：

switch (userInputCar.toUpperCase()) {
    case "TATA":
        System.out.println("You enter TATA as a car name");
        break;
    case "BMW":
        System.out.println("You enter BMW as a car name");
        break;
    default:
        System.out.println("Oops! we are unable to get that name. Thank You:");
}

注意如何使用

userInputCar.toUpperCase()

。这允许用户以任何字母大小写输入汽车名称，仍然会产生肯定的结果。

在任何情况下...由于汽车名称已经包含在字符串 [] 数组 (

cars[]

) 中，您应该检查名称数组而不是创建

switch/case

机制来执行此操作，例如：

// Declare Scanner object as class global:
private final static Scanner sc = new Scanner(System.in);
    
public static String getCarName() {
    String[] cars = {"TATA", "BMW", "Hero", "Honda", "Bajaj", "Yamaha"};

    String carName = "";
    while (carName.isEmpty()) {
        System.out.print("Enter a car name (q to quit): -> ");
        carName = sc.nextLine();
        // See if 'q' for quit was supplied by User:
        if (carName.equalsIgnoreCase("q")) {
            return null;
        }
            
        // Flag to indicate that supplied car was found within Array:
        boolean found = false; 
        /* Iterate the the cars[] array and see if the User supplied
           car exists within that array (ignoring letter case):   */
        for (String car: cars) {
            if (car.equalsIgnoreCase(carName)) {
                /* The supplied car name exists. Make the supplied 
                   car name equal the proper car name in array: */
                carName = car;
                found = true;  // Set the `found` flag to true:
                break;         // Break out of `for` loop:
            }
        }
        // Was the supplied car name found?
        if (!found) {
            // No...Inform User and have him/her try again...
            System.out.println("Oops! We are unable to get that name (" 
                             + carName + "). Try again..." 
                             + System.lineSeparator());
            carName = "";  // Empty carName to ensure re-loop:
        }
    }
        
    /* If we get to this point then validation was successfull,
       return the car name:   */
    return carName;
}

使用上面的方法，你可能会遇到这样的情况：

String car = getCarName();
if (car == null) {
    System.out.println("'Quit' Provided!"); 
    return;
}
System.out.println("You entered " + car +  " as a car name.");