Java - 密码生成器

Question

我正在将其作为一个项目来完成。其要点是使用您选择的字符类型和您选择的长度创建一个密码。但是当我使用选项 D 时，它不会返回任何内容，而在选项 B 和 C 上，无论我输入的长度如何，我总是会得到随机数量的字符。如果您可以运行它，并为我指出解决此问题的正确方向，我将不胜感激。

import java.util.Scanner;

public class Password
{
    public static void main(String [] args){
        String password = "";
        String temp = "";
        int randLetter = 0;
        int randNumber = 0;
        int randPunct = 0;
        int charSelection = 0;
        int counter = 0;
        String lowerCase = "abcdefghijklmnopqrstuvwxyz";
        String upperCase = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
        String number = "0123456789";
        String punctuation = "!?";


        Scanner in = new Scanner(System.in);

        System.out.println("Please choose what characters you would like to use.");
        System.out.println("[A] Lowercase Letters");
        System.out.println("[B] Lowercase & Uppercase Letters");
        System.out.println("[C] Lowercase, Uppercase, Numbers");
        System.out.println("[D] Lowercase, Uppercase, Numbers, Punctuation");
        System.out.print("Selection: ");
        String selection = in.next();

        System.out.println();
        System.out.print("Select a length (1 - 14): ");
        int length = in.nextInt();

        if(selection.equalsIgnoreCase("A")){
            for (int i = 0; i < length; i++){
                randLetter = 1 + (int)(Math.random() * 26); 
                temp = lowerCase.substring(randLetter - 1 , randLetter); 
                password += temp;    
            }
        }
        else if(selection.equalsIgnoreCase("B")){
            while (counter < length){
                for (int i = 0; i < length; i++){

                    charSelection = 1 + (int)(Math.random() * 10); 

                    if (charSelection < 5){

                        randLetter = 1 + (int)(Math.random() * 26); 
                        temp = lowerCase.substring(randLetter - 1 , randLetter);
                        counter++;
                        password += temp;  
                    }
                    else if (charSelection > 5 && charSelection < 10){

                        randLetter = 1 + (int)(Math.random() * 26); 
                        temp = upperCase.substring(randLetter - 1 , randLetter);
                        counter++;
                        password += temp;  
                    }
                }
            }
        }
        else if(selection.equalsIgnoreCase("C")){
            while (counter < length){
                for (int i = 0; i < length; i++){

                    charSelection = 1 + (int)(Math.random() * 17);
                    randNumber = 1 + (int)(Math.random() * 9);

                    if (charSelection < 5){

                        randLetter = 1 + (int)(Math.random() * 26); 
                        temp = lowerCase.substring(randLetter - 1 , randLetter);
                        counter++;
                        password += temp;
                    }
                    else if (charSelection > 5 && charSelection < 10){

                        randLetter = 1 + (int)(Math.random() * 26); 
                        temp = upperCase.substring(randLetter - 1 , randLetter);
                        counter++;
                        password += temp;
                    }
                    else if (charSelection > 15 && charSelection < 17){

                        randLetter = 1 + (int)(Math.random() * 26); 
                        temp = number.substring(randNumber - 1 , randNumber);
                        counter++;
                        password += temp;
                    }
                }
            }
        }
        else if(selection.equalsIgnoreCase("D")){
            while (counter < length){
                for (int i = 1; i < 0; i++){

                    charSelection = 1 + (int)(Math.random() * 20); 
                    randNumber = 1 + (int)(Math.random() * 9);
                    randPunct = 1 + (int)(Math.random() * 2);
                    if (charSelection < 5){

                        randLetter = 1 + (int)(Math.random() * 26); 
                        temp = lowerCase.substring(randLetter - 1 , randLetter);
                        counter++;
                        password += temp;
                    }
                    else if (charSelection > 5 && charSelection < 10){

                        randLetter = 1 + (int)(Math.random() * 26); 
                        temp = upperCase.substring(randLetter - 1 , randLetter);
                        counter++;
                        password += temp;
                    }
                    else if (charSelection > 15 && charSelection < 17){

                        randLetter = 1 + (int)(Math.random() * 26); 
                        temp = number.substring(randNumber - 1 , randNumber);
                        counter++;
                        password += temp;                 
                    }
                    else if (charSelection > 17){

                        randLetter = 1 + (int)(Math.random() * 26); 
                        temp = punctuation.substring(randPunct - 1 , randPunct);
                        counter++;
                        password += temp;   
                    }
                } 
            }
        }
        System.out.println(password);
    }
}

Answer 1

for (int i = 1; i < 0; i++){

这个条件永远不会成立，因此循环体永远不会执行。

目前尚不清楚您在这里的真正意图，因此很难建议正确的条件 - 您的意思是 length 而不是 0，就像您在其他循环中所做的那样？