java - 基本java中存在导入、类困惑

Question

我有一个程序，它导入一个字符串文件，解析它以获取正确的单词，然后过滤并打印唯一的单词。我已经设置了一个类来导入 .txt 文件并将单词放入 ArrayList 中:

public class RawText 
{
    ArrayList<String> allWords = new ArrayList<String>();  //raw list of words

/**
 * This method reads strings from file, filters for only upper/lowercase strings and adds to allWords
 * @throws IOException 
 * @params filename: a string filename
 */
public void add(String filename) throws IOException
{
    File inFile = new File(filename);         //inst. file import for raw
    Scanner read = new Scanner(inFile);         //inst. scanner object

    while (read.hasNext())                      //reads until end of text
    {
        String word = read.next();              //scanner reads next complete string
        word = word.replaceAll("[^a-zA-Z", ""); //filters out non-alphabet chars
        allWords.add(word);                     //adds 'stripped-down' string to list
    }
    read.close();
}

}

以及Main()，过滤方法和打印:

public class Source1 {
static ArrayList<String> allWords = new ArrayList<String>();
static ArrayList<String> uniqueWords = new ArrayList<String>();

/**
 * @param args the command line arguments
 */
public static void main(String[] args) 
{
    RawText rt = new RawText();             //Inst. class for import
    Source1 source = new Source1();         //Inst. class variables
    rt.add("text.txt");                     //creates arraylist of raw words
    removeRepeats();                        //run method to filter out repeats

    printArray(source.allWords);            //prints unfiltered array
    printArray(source.uniqueWords);         //prints filtered array
}

/**
 * matches words against previously used words, and strips out repeats
 * @params words any string array to be filtered for repeat words
 */
public static void removeRepeats()
{
    boolean isUnique = false;           //default State for rejecting repeat words
    uniqueWords.add(0) = allWords.get(0);//Prime the matching algorithm at first word

    int i = 0;                          //i counts up each raw word to be tested
    while (i < allWords.size())
    {
        int j = 0;                      //j counts up each previous unique word
        while (j < uniqueWords.size())  //runs through all current uniques
        {
            isUnique = true;            //set state to true
            if (allWords.get(i) == uniqueWords.get(j))
                isUnique = false;       //if any words match, eval to false
            j++;
        }

        if (isUnique = true)            //Only if state remains true, add raw word to uniques
            uniqueWords.add(allWords.get(i));
        i++;
    }
}

我需要知道是否有更合适/有效的方法来设置我的类，以及 uniquewords.add() 是否有原因无法在 removeRepeats() 方法的第二行中工作。

谢谢。

Answer 1

您的一些问题:

uniqueWords.add(0) = allWords.get(0);

在这里，您将一个整数 0 添加到字符串的 ArrayList 中。您可能想要:

uniqueWords.add(allWords.get(0));

此外，稍后您将字符串与 == 进行比较:

if (allWords.get(i) == uniqueWords.get(j))

== 仅应在比较原始数据类型时使用。要比较字符串，请使用 equals(String) 或 equalsIgnoreCase(String) 方法:

if (allWords.get(i).equalsIgnoreCase(uniqueWords.get(j))