如何获取用户输入，将其添加到新扫描仪，然后将输入扫描到数组中？

Question

我试图创建一个程序，它接受用户的输入，然后用for循环扫描用户输入到数组中。这样我可以遍历数组来查找该字符串是否是一个单词回文。单词回文不同于回文，因为它是整个单词的反向，而不是每个单独的字母。当我编写的程序打印时，它只是打印出空白，我相信这意味着它不存储扫描仪扫描的内容。 下面是我写的东西：

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

你已经有了一些时髦的逻辑怎么回事。有几件事情：

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

userInputLength是userInput字符串，它是一个字符的字符串中的数量，而不是字的数量的长度。

它看起来像while循环仅用于计算所需的数组大小，但外部for循环不是必需的。你有效地说，对于输入字符串中的每个字符，当扫描器有另一个单词时，计数单词，这没有多大意义。

你在你的第二个for循环中做了类似的事情，这也没有多大意义。

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

它会更容易使用List和保存自己，带有固定大小的数组的麻烦。您可以初始化列表并添加内容，而不必关心它有多大。

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

下面是一些代码来简化你的问题有点：

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

我做了一些改动（删除for循环和额外的迭代），请参考代码中的注释：

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