Question

我的问题是在文本文件中查找和替换字符串。此程序应在ghost文本文件中查找单词A Christmas Carol的实例，并将bunny替换为ghost，将Bunny替换为Ghost }和BUNNY GHOST。它适用于小写鬼，并且没有GHOST的实例，但它似乎不适用于大写的Ghost。我知道我的问题属于最后两种方法。我做错了什么？

    package findandreplace;

    import java.io.File;
    import java.io.FileNotFoundException;
    import java.io.PrintWriter;
    import java.util.ArrayList;
    import java.util.Scanner;


    public class FindAndReplace {


    public static void main(String[] args) {
        String filename = "24022-0.txt"; //Charles Dickens - A Christmas Carol
        try {
            Scanner fin = getScannerFromFile(filename);
            String [] story = readFile(fin);
            String [] newStory = new String[story.length];

            for (int i = 0; i < story.length; i++) {
                newStory[i] = substitute(story[i], "ghost", "bunny");
            }

            if (writeFile("bunny.txt", newStory))
                System.out.println("New file successfully created.");

        } catch (FileNotFoundException e) {
            System.out.println("File not found");
            System.exit(1);
        }
    }

    private static Scanner getScannerFromFile(String filename) throws FileNotFoundException {
        File f = new File(filename);
        return new Scanner(f);
    }



    private static String [] readFile(Scanner fin) {
        ArrayList<String> lines = new ArrayList<>();
        while (fin.hasNext()) {
            lines.add(fin.nextLine());
        }
        return lines.toArray(new String[0]);
    }


    private static boolean writeFile(String newfile, String [] lines) {
        File file = new File(newfile);
        if (file.exists()) {
            System.out.println("File already exists");
        }
        try {
            PrintWriter fout = new PrintWriter(file);
            for (String line : lines) {
                fout.println(line);
            }
            fout.close();
        } catch (FileNotFoundException ex) {
            System.err.println("File error.");
            return false;
        } 
        return true;
    }

    /**
     * This method should examine the first word, and return the second word matching case.
     * For example, if first word is "GHOST", and second word is "bunny", the return value
     * should be "BUNNY".
     * NOTE: THIS SHOULD *NOT* BE A RECURSIVE FUNCTION
     * precondition: the first word is all lowercase, Capitalized, or ALL-CAPS
     * @return second, matching case of first
     */
    private static String matchWordCase(String first, String second) {
         if (first.toUpperCase().equals(first)) {
         second = second.toUpperCase();
        }
        if (first.toLowerCase().equals(first)) {
            second = second.toLowerCase();
        }
        else if (first.toUpperCase().charAt(0) == first.charAt(0)) {
            second = second.substring(0, 1).toUpperCase() + second.substring(1);
        }
        return second;
    } 

    /**
     * This method should return line, with every instance of the word find
     * should be replaced by replace. There are multiple approaches you can take,
     * but words should match regardless of case, and case should be preserved.
     * If you want to assume words are space-separated, you may. However, it is
     * better if you figure out how to do this otherwise.
     * NOTE: THIS SHOULD BE A RECURSIVE FUNCTION
     * @return line - with the appropriate substitutions
     */
    private static String substitute(String line, String find, String replace) {
        StringBuilder newLine = new StringBuilder();
        //TODO:
        String result;
        if (line.length() < find.length()) {
            return line;
        }

        if (find.equals(line.substring(0,find.length()))) {
         line = matchWordCase(find, replace) + 
         substitute(line.substring(find.length()), find, matchWordCase(find, 
         replace));
        } else {
            result = line.charAt(0) + substitute(line.substring(1), find, 
        replace);
        }


        return result;
    }
}

Answer 1

在substitute方法的if语句中，条件是find.equalsIgnoreCase，而不是find.equals吗？

递归查找和替换字符串？

1 个答案: