用其他数组制作一个大数组，如果错误则使其变小

Question

我一直在研究这个创建密码的程序，它有4个char数组，其中我拥有可用于密码的所有字符，以及评估用户是否想要使用它们的方法，问题是它仅在所有数组都为“true”（它们被使用）时才有效，因为最后一个数组由73个空格组成，这些空格用其他数组填充。问题是，如果用户不想使用其中一个，当for循环遍历数组时，它将主要落在一个空的索引号上打破代码，我想不出一种方法来克服这个问题

package javaapplication19;

import java.util.Scanner;
import java.util.concurrent.ThreadLocalRandom;

public class JavaApplication19 {

    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);

        char [] leterSmall = {'a','b','c','d','e','f','g','h','i','j','k','l','m','n','ñ','o','p','q','r','s','t','u','v','w','x','y','z'}; 
        char[] leterBig = {'A','B','C','D','E','F','G','H','I','J','K','L','M','N','Ñ','O','P','Q','R','S','T','U','V','W','X','Y','Z'};
        char[] numbers = {'0','1','2','3','4','5','6','7','8','9'};
        char [] charsRandom = {'?','¿','.',';','+','-','*','/','|'};
        char [] arrayFinal = new char[73];

        boolean smallOption = false;
        boolean bigOption= false;
        boolean numbersOption= false;
        boolean charactersOption= false;

        System.out.println("Do you want to use small leters?");
        String answer1 = sc.next();
        if( opcionmenu(answer1)==true){
            smallOption = true;
             for(int i=0;i<27;i++){
                arrayFinal[i]=leterSmall[i];
            }
        }
        System.out.println("Do you want to use big leters?");
        String answer2 = sc.next();
        if( opcionmenu(answer2)==true){
            bigOption = true;
             for(int i=27;i<54;i++){
                arrayFinal[i]=leterBig[i-27];
            }
        }
        System.out.println("Do you  want to use numbers?");
        String answer3 = sc.next();
        if( opcionmenu(answer3)==true){
            numbersOption = true;
             for(int i=54;i<64;i++){
                arrayFinal[i]=numbers[i-54];
            }
        }
        System.out.println("Do you want to use symbols?");
        String answer4 = sc.next();
        if( opcionmenu(answer4)==true){
            charactersOption = true;
             for(int i=64;i<73;i++){
                arrayFinal[i]=charsRandom[i-64];
            }
        }

        for(int i=0;i<16;i++){
           int y = ThreadLocalRandom.current().nextInt(0,73 + 0 );   
           System.out.print(arrayFinal[y]);

        }




    }
       static boolean opcionmenu(String stra){

        if(stra.equals("Yes")) {
             return true;
        }
        else{
            return false;
         }
       }              
}

Answer 1

构建arrayFinal时，请跟踪您添加的值的数量，并且仅在之前的值之后添加值。

像这样，len是添加到arrayFinal的字符数：

int len = 0;
if (smallOption) {
    for (char c : leterSmall) {
        arrayFinal[len++] = c;
    }
}
if (bigOption) {
    for (char c : leterBig) {
        arrayFinal[len++] = c;
    }
}
if (numbersOption) {
    for (char c : numbers) {
        arrayFinal[len++] = c;
    }
}
if (charactersOption) {
    for (char c : charsRandom) {
        arrayFinal[len++] = c;
    }
}

ThreadLocalRandom rnd = ThreadLocalRandom.current();
for (int i = 0; i < 16; i++) {
    System.out.print(arrayFinal[rnd.nextInt(len)]);
}

Answer 2

你可以使用System.arraycopy()方法。避免这个问题。

如

 int length = 0 ;
if( opcionmenu(answer2)==true){


        System.arraycopy(leterBig ,0 ,arrayFinal,length,leterBig.length);
        length = length + leterBig.length ;


    }
// and so on
for(int i=0;i<16;i++){
            int y = ThreadLocalRandom.current().nextInt(0,length );
            System.out.print(arrayFinal[y]);

        }