Question

好的，稍微修改了代码，但是程序仍然无法正常工作。我希望能够在程序运行时在Java控制台中输入产品类型（水果），输入任何类型的水果（香蕉，苹果或橙子），然后输入数量。

import java.util.*;

public class demo {

public static void main(String[] args) {

    Scanner sc = new Scanner(System.in);

    String str[] = { "Bananas", "Apples", "Oranges" };
    double price[] = { 2.09, 2.59, 2.25 };
    int i = 0;
    int j = 0;

    System.out.print("Enter type of product: ");
    String string = sc.nextLine();
    if ("fruit".equals(string)) {
        while (i < str.length) {
            while (j < price.length) {
                System.out.print(str[i++] + ": " + "£" + (price[j++]) + "p per bag \n");

            }
        }
    }
    System.out.print("\n");
    System.out.print("Enter which type of " + string + ": ");

    String string1 = sc.nextLine();

    boolean strs = "bananas".equals(string1);
    boolean strs1 = "apples".equals(string1);
    boolean strs2 = "oranges".equals(string1);
    if (strs) {
        System.out.print("Enter qty of " + str[0] + " (by bag): ");
    }

    if (strs1) {
        System.out.print("Enter qty of " + str[1] + " (by bag): ");

    }
    if (strs2) {
        System.out.print("Enter qty of " + str[2] + " (by bag): ");
    }

    int qty = sc.nextInt();
    int[] a = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };
    int h = 1;
    if ((a[h] == (qty)) && (strs) || (strs1) || (strs2)){
        System.out.print("\n");
        System.out.print(qty + " bag(s) of " + string1 + " have been added to your basket, " + "total costing £"
                + (qty) * price[0] + "p");

        }
    }   
}

还有其他想法吗？

Answer 1

错误发生在String string = sc.next（“ fruit”）;可以将其更改为sc.nextLine（）或类似下面的内容

public static void main(String[] args) {

Scanner sc = new Scanner(System.in);

String str[] = { "Bananas", "Apples", "Oranges" };
double stk[] = { 1.09, 1.59, 1.25 };
int i = 0;
int j =0;

try {
    System.out.print("Enter type of product: ");
    String string = sc.next();

    while (i < str.length) {
        while (j < stk.length) {
        System.out.print(str[i++] + ": " + "£" + (stk[j++]) + "p per bag \n");

        }
    }
    System.out.print("\n");
    System.out.print("Enter which type of "+string+": ");
    String string1 = sc.next();
    if(string1 != null) {
        System.out.print("Enter qty of "+string1+ "(per bag) \n");
    } 
    String string2 = sc.next();     
    if(string2 != null) {
            System.out.print("Enter qty of " +string2+ "(in lbs) \n");

    } 
    String string3 = sc.next();
    if (string3 != null) {
            System.out.print("Enter qty of " +string3+ "(in lbs) \n");

    }

} catch (Exception e) {
    System.out.println("Eror");
    e.printStackTrace();
    }
}

Answer 2

您遇到的错误是正在读取字符串。

替换

String string = sc.next("fruit");          // Line 17
String string1 = sc.next("bananas");       // Line 26
String string2 = sc.next("apples");        // Line 30
String string3 = sc.next("oranges");       // Line 35

使用

String string = sc.nextLine();             // Line 17
String string1 = sc.nextLine();            // Line 26
String string2 = sc.nextLine();            // Line 30
String string3 = sc.nextLine();            // Line 35

如果要检查输入的String，请使用以下代码：-

if(string.equals("fruit")){ 
   // statements
}

Answer 3

根据JavaDoc，您得到的InputMismatchException是

由Scanner抛出
表示检索到的令牌没有匹配预期类型的模式，或者令牌不足预期类型的范围。

因此，如果您没有按照请求（"fruit"）来写String string = sc.next("fruit")，则执行将因该异常而终止。因此，要修复您的代码，您应该替换

String string = sc.next("fruit");

类似

String string = sc.nextLine();
if ("fruit".equalsIgnoreCase(string)) { /* design your control flow as you want */

您可以将相同的规则应用于代码中存在的其他sc.next()。

旁注：切勿将异常吞入catch块中；始终记录它们。

Answer 4

您对输入行的扫描是错误的。要在Java中扫描输入数据，您应该使用

Scanner in = new Scanner(System.in);
int a = in.nextInt(); // To input integer
char ch = in.nextChar(); // To input character
String str = in.nextLine(); // To get a complete line of input
String s = in.next(); //To get a single string

根据上述内容替换输入行。

干杯：）

无法使该Java程序正常工作

4 个答案: