Java制表符与空格的转换之EnTab和DeTab的使用

public class EnTab {
    protected Tabs tabs;

    public EnTab(int n) {
        tabs = new Tabs(n);
    }

    public void entab(BufferedReader is, PrintWriter out) throws IOException {
        is.lines().forEach(line -> out.println(entabLine(line)));
    }

    public String entabLine(String line) {
        int N = line.length(), outCol = 0;
        StringBuilder sb = new StringBuilder();
        int consumedSpaces = 0;

        for (int inCol = 0; inCol < N; inCol++) {
            char ch = line.charAt(inCol);
            if (ch == ' ') {
                if (tabs.isTabStop(inCol)) {
                    sb.append('\t');
                    outCol += consumedSpaces;
                    consumedSpaces = 0;
                } else {
                    consumedSpaces++;
                }
                continue;
            }
            while (inCol - 1 > outCol) {
                sb.append(' ');
                outCol++;
            }
            sb.append(ch);
            outCol++;
        }
        for (int i = 0; i < consumedSpaces; i++) {
            sb.append(' ');
        }
        return sb.toString();
    }
}

public class DeTab {
    Tabs ts;

    public DeTab(int n) {
        ts = new Tabs(n);
    }

    public void detab(BufferedReader is, PrintWriter out) throws IOException {
        is.lines().forEach(line -> out.println(detabLine(line)));
    }

    public String detabLine(String line) {
        StringBuilder sb = new StringBuilder();
        int col = 0;
        for (int i = 0; i < line.length(); i++) {
            char c = line.charAt(i);
            if (c != '\t') {
                sb.append(c);
                ++col;
                continue;
            }
            do {
                sb.append(' ');
            } while (!ts.isTabStop(++col));
        }
        return sb.toString();
    }
}

public class Tabs {
    public final static int DEFTABSPACE = 8;
    protected int tabSpace = DEFTABSPACE;

    public Tabs(int n) {
        tabSpace = n > 0 ? n : 1;
    }

    public boolean isTabStop(int col) {
        if (col <= 0) return false;
        return (col + 1) % tabSpace == 0;
    }
}

import java.io.*;

public class Main {
    public static void main(String[] args) throws IOException {
        // 将文件中的空格转换为制表符
        EnTab et = new EnTab(8);
        et.entab(
            new BufferedReader(new FileReader("input.txt")),
            new PrintWriter("output.txt")
        );

        // 将文件中的制表符转换为空格
        DeTab dt = new DeTab(8);
        dt.detab(
            new BufferedReader(new FileReader("output.txt")),
            new PrintWriter("result.txt")
        );
    }
}

        Hello
    World

\tHello
\tWorld

        Hello
    World