Java，將字符串存儲到數組中

Question

我希望將以這種方式輸入的原始問題（rawQuestions）在命令提示符下：java Hangman Hello test 123放入數組（問題）。 我知道rawQuestion不會在“將有效問題存儲到數組中”部分中工作，因為

• “錯誤：';' 預期的”和“錯誤：不是聲明”

在行中

• “ questions [vCount] =字符串rawQuestion;”

因此，我應該如何重寫它？

public class Hangman {

    //Validation of raw questions

    public static boolean isValidQuestion(String rawQuestion){
        rawQuestion = rawQuestion.toUpperCase();
        boolean vQuestion = true;
        for(int i=0; i<rawQuestion.length(); i++){
            char c = rawQuestion.charAt(i);

            if(!(c>='A' && c<='Z'))
            vQuestion = false;
        }
        return vQuestion;
    }


    public static void main(String args[]){

        boolean vQs[] = new boolean[args.length];

        for(int i=0; i<args.length; i++){

            String rawQuestion = args[i];

            boolean b = isValidQuestion(rawQuestion);

            if(b)
                 System.out.println(rawQuestion + " is a valid question!");

            else
                 System.out.println("Error: " + rawQuestion + ", input must be a word consist of a-z or A-Z");

            vQs[i] = b;
        }

        //count the number of valid questions

        int vCount = 0;
        for(int i=0; i<vQs.length; i++){
            System.out.println(i + " " + vQs[i] );
            if(vQs[i])
                vCount++;
        }
        System.out.println("There are " + vCount + " valid questions");

        //store valid questions into an array

        String questions[] = new String[vCount];
        for(vCount=0; vCount<args.length; vCount++){
            questions[vCount] = String rawQuestion;
            System.out.println( questions[vCount] );


        }

    }
}

Answer 1

嘗試這個：

String[] validQuestions = Arrays.stream(args)
                                .filter(Hangman::isValidQuestion)
                                .toArray(String[]::new);
int validQuestionCount = validQuestions.length;

但是，即使沒有Streams，您也可以在一個for循環中完成整個方法，一次性計算和收集有效問題，而無需執行三個單獨的步驟：

List<String> validQuestions = new ArrayList<>();
for (int i = 0; i < args.length; i++)
{
    String rawQuestion = args[i];
    boolean b = isValidQuestion(rawQuestion);
    if (b)
    {
        validQuestions.add(rawQuestion);
        System.out.println(rawQuestion + " is a valid question!");
    }
    else
    {
        System.out.println("Error: " + rawQuestion + ", input must be a word consist of a-z or A-Z");
    }
}

// count the number of valid questions
System.out.println("There are " + validQuestions.size() + " valid questions");

// store valid questions into an array
String questions[] = validQuestions.toArray(new String[validQuestions.size()]);

這樣，您不必自己弄亂索引變量，這很難理解，特別是在其他人嘗試讀取索引變量的情況下。 （特別是vCount的重復使用對vCount來說有點嚇人）

Answer 2

我修復了一些問題並發表了評論，不確定它是否有效，我還沒有編譯它。

public static void main(String args[]){

boolean vQs[] = new boolean[args.length];
int vCount=0;

for(int i=0; i<args.length; i++){

    String rawQuestion = args[i];

    if(isValidQuestion(rawQuestion)){


    System.out.println(rawQuestion + " is a valid question!");
            //Here you have enough data to count the valid questions, three loops are not needed.
            ++vCount;
            vQs[i]=true;
        }else{
            System.out.println("Error: " + rawQuestion + ", input must be a word consist of a-z or A-Z");
            vQs[i]=false;
        }
    }

    System.out.println("There are " + vCount + " valid questions");

    //store valid questions into an array
    String questions[] = new String[vCount];

    int j=0;
    for(int i=0; i<args.length; i++){
        //You need to iterate for all strings, because vQs[] is long args.length
        if(vQs[i]){
            //Ok the i-th question was valid, let's move it and print it
            questions[j] = args[i];
            System.out.println( questions[j] );
            ++j;
        }
    }

}

}