如何獲取用戶輸入，將其添加到新掃描儀，然後將輸入掃描到數組中？

Question

我試圖創建一個程序，它接受用戶的輸入，然後用for循環掃描用戶輸入到數組中。這樣我可以遍歷數組來查找該字符串是否是一個單詞迴文。單詞迴文不同於迴文，因爲它是整個單詞的反向，而不是每個單獨的字母。當我編寫的程序打印時，它只是打印出空白，我相信這意味着它不存儲掃描儀掃描的內容。 下面是我寫的東西：

String userInput, scannedWord; 
Scanner keyboard = new Scanner(System.in); //scanner for user input 

System.out.print("Please enter a sentence: "); 
userInput = keyboard.nextLine(); //stores user input 

Scanner stringScan = new Scanner(userInput); //scanner to scan through user input 

int userInputLength = userInput.length(); //to find word count 
int wordCount = 0; //for array size 


for (int i = 0; i < userInputLength; i++) //finds word count 
{ 
    while(stringScan.hasNext()) 
    { 
     scannedWord = stringScan.next(); 
     wordCount = wordCount + 1; 
    } 
} 

String stringArray[] = new String[wordCount]; 

    for (int i = 0; i < userInputLength; i++) //should store scanned words into the array 
    { 
    while (stringScan.hasNext()) 
    { 
     scannedWord = stringScan.next(); 
     stringArray[i] = scannedWord; 
    } 
    } 

System.out.println(Arrays.toString(stringArray)); //how I've checked if it's storing 

Answer 1

你已經有了一些時髦的邏輯怎麼回事。有幾件事情：

userInput = keyboard.nextLine(); //stores user input 
int userInputLength = userInput.length(); //to find word count 

userInputLength是userInput字符串，它是一個字符的字符串中的數量，而不是字的數量的長度。

它看起來像while循環僅用於計算所需的數組大小，但外部for循環不是必需的。你有效地說，對於輸入字符串中的每個字符，當掃描器有另一個單詞時，計數單詞，這沒有多大意義。

你在你的第二個for循環中做了類似的事情，這也沒有多大意義。

for (int i = 0; i < userInputLength; i++) //finds word count 
{ 
    while(stringScan.hasNext()) 
    { 
     scannedWord = stringScan.next(); 
     wordCount = wordCount + 1; 
    } 
} 

它會更容易使用List和保存自己，帶有固定大小的數組的麻煩。您可以初始化列表並添加內容，而不必關心它有多大。

List<String> words = new ArrayList<String>(); 
words.add(word1); 
words.add(word2); 

下面是一些代碼來簡化你的問題有點：

Scanner keyboard = new Scanner(System.in); //scanner for user input 

System.out.print("Please enter a sentence: "); 

String userInput = keyboard.nextLine(); //stores user input 

Scanner stringScan = new Scanner(userInput); //scanner to scan through user input 

List<String> words = new ArrayList<String>(); 

while (stringScan.hasNext()) 
{ 
    String scannedWord = stringScan.next(); 
    words.add(scannedWord); 
} 

System.out.print(Arrays.toString(words.toArray())); // nasty! but you can see what's in the array for debugging 

Answer 2

我做了一些改動（刪除for循環和額外的迭代），請參考代碼中的註釋：

String userInput; 
Scanner keyboard = new Scanner(System.in); // scanner for user input 

System.out.print("Please enter a sentence: "); 
userInput = keyboard.nextLine(); // stores user input 

// *** CHANGE- we can directly store the array of words separated by space 
String stringArray[] = userInput.split(" "); 

System.out.println(Arrays.toString(stringArray)); // how I've checked if 
                 // it's storing 
keyboard.close(); // Closing scanner