为什么输入密钥后我的程序退出

Question

我对这个问题感到困惑，无法理解为什么输入第一个数据后总是退出程序。 如何输入字符串数据？

import java.util.Scanner;
public class Caesar {

    public static String encode(String enc, int offset) {
        offset = offset % 26 + 26;
        StringBuilder encoded = new StringBuilder();
        for (char i : enc.toCharArray()) {
            if (Character.isLetter(i)) {
                if (Character.isUpperCase(i)) {
                    encoded.append((char) ('A' + (i - 'A' + offset) % 26 ));
                } else {
                    encoded.append((char) ('a' + (i - 'a' + offset) % 26 ));
                }
            } else {
                encoded.append(i);
            }
        }
        return encoded.toString();
    }


    public static void main(String[] args) {

        Scanner in = new Scanner(System.in);
        System.out.print("Enter key: ");
        int key = in.nextInt();
        System.out.print("Enter line: ");
        String str = in.nextLine();

        System.out.println( Cipher.encode( str, key ));

    }
}

Answer 1

因为当您输入Key您还要按下<ENTER>键。 需要先消耗掉此字符，然后再尝试

    Scanner in = new Scanner(System.in);
    System.out.print("Enter key: ");
    int key = in.nextInt();
    in.nextLine();
    System.out.print("Enter line: ");
    String str = in.nextLine();

    System.out.println( Cipher.encode( str, key ));

Answer 2

 Scanner in = new Scanner(System.in);
        System.out.print("Enter key: ");
        int key = in.nextInt();
        System.out.print("Enter line: ");
        if (in.hasNext()) {
            String str = in.nextLine();
        }

或者你可以在一段while获得输入