java - 程序连续两次打印菜单

Question

我正在制作一个类似证书的程序，它还处于开发阶段。我放置了一个带有 boolean 条件的 while 循环，以使程序在一个人完成创建凭证时再次运行，但是当它循环到程序的开头时，它会打印第一部分两次!像这样:

run:
     |-----------------------------------------------|
     |Welcome to the Credential Managing System 2013!|
     |-----------------------------------------------|

      Would you like to create or manage a credential?

                 Choose: Manage | Create

                    Waiting for input: Create

Credential name: df
Credential ID: 34243
Credential Password: numbers or words?
Waiting for input: numbers
Credential Password: 13651

                      |-------------------|
                      |Credential created!|
                      |-------------------|




      Would you like to create or manage a credential?

                 Choose: Manage | Create

                    Waiting for input:

从那里它再次停止读取输入。

这是完整的代码!

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */

/**
 *
 * @author Carlinhos
*/
import java.util.Scanner;

public class Criação {

public static void main(String[] args){
Scanner e = new Scanner(System.in);



System.out.println("         |-----------------------------------------------|");
System.out.println("         |Welcome to the Credential Managing System 2013!|");
System.out.println("         |-----------------------------------------------|");
System.out.println("");

Boolean autoRun = true;

while(autoRun){

System.out.println("          Would you like to create or manage a credential?");
System.out.println("");
System.out.println("                     Choose: Manage | Create");
System.out.println("");
System.out.print("                        Waiting for input: ");

String op1 = e.nextLine();
autoRun = false;

if(op1.equals("Create")){

    System.out.println();
    System.out.print("Credential name: ");
    String credName = e.nextLine();
    System.out.print("Credential ID: ");
    int credID = e.nextInt();
    System.out.println("Credential Password: numbers or words?");
    System.out.print("Waiting for input: ");
    e.nextLine();
    String credPassCheck = e.nextLine();

    if(credPassCheck.equals("numbers")){

        System.out.print("Credential Password: ");
        double credPassNum = e.nextDouble();
        }

    else if(credPassCheck.equals("words")){

        System.out.print("Credential Password: ");
        String credPassLet = e.nextLine();
        }

    System.out.println("");
    System.out.println("                          |-------------------|");
    System.out.println("                          |Credential created!|");
    System.out.println("                          |-------------------|");
    System.out.println("");
    System.out.println("");
    System.out.println("");
    System.out.println("");

    autoRun = true;

        }
    }
}
}

Answer 1

更改此行:

while(autoRun = true)

对此:

while(autoRun)

= 不是相等比较运算符，而是赋值运算符。因此，当您检查条件 autoRun 时，即使您之前将其设置为 false，也会分配值 true。您可以使用 == 代替，但由于 autoRun 是一个 boolean 变量，因此您可以简单地使用此变量，而无需将其与其他任何内容进行比较。

更新:

在OP评论第二次打印提示后程序已开始退出后，我进一步查看了代码并发现了这些行:

if(credPassCheck.equals("numbers")){
    System.out.print("Credential Password: ");
    double credPassNum = e.nextDouble();
}

这基本上消耗的输入少于所需的输入，因此“等待输入”的下一个提示将获得一个换行符作为其输入。现在修复应该很明显:

if(credPassCheck.equals("numbers")){
    System.out.print("Credential Password: ");
    double credPassNum = e.nextDouble();
    e.nextLine(); //Add this Line
}