// Static functions for reading and writing text files as

// a single string, and treating a file as an ArrayList.

package thinkinginjava.util;

import java.io.*;

import java.util.*;

public class TextFile extends ArrayList<String> {

// Read a file as a single string:

public static String read(String fileName) {

StringBuilder sb = new StringBuilder();

try {

BufferedReader in = new BufferedReader(new FileReader(new File(

fileName).getAbsoluteFile()));

try {

String s;

while ((s = in.readLine()) != null) {

sb.append(s);

sb.append("\n");

}

} finally {

in.close();

}

} catch (IOException e) {

throw new RuntimeException(e);

}

return sb.toString();

}

// Write a single file in one method call:

public static void write(String fileName, String text) {

try {

PrintWriter out = new PrintWriter(

new File(fileName).getAbsoluteFile());

try {

out.print(text);

} finally {

out.close(); // 注意这里

}

} catch (IOException e) {

throw new RuntimeException(e);

}

}

// Read a file, split by any regular expression:

public TextFile(String fileName, String splitter) {

super(Arrays.asList(read(fileName).split(splitter)));

// Regular expression split() often leaves an empty

// String at the first position:

if (get(0).equals(""))

remove(0);

}

// Normally read by lines:

public TextFile(String fileName) {

this(fileName, "\n"); // 默认以换行符来分割

}

public void write(String fileName) {

try {

PrintWriter out = new PrintWriter(

new File(fileName).getAbsoluteFile());

try {

for (String item : this)

out.println(item);

} finally {

out.close();

}

} catch (IOException e) {

throw new RuntimeException(e);

}

}

// Simple test:

public static void main(String[] args) {

String file = read("TextFile.java");

write("test.txt", file);

TextFile text = new TextFile("test.txt");

text.write("test2.txt");

// Break into unique sorted list of words:

TreeSet<String> words = new TreeSet<String>(new TextFile(

"TextFile.java", "\\W+"));

// Display the capitalized words:

System.out.println(words.headSet("a"));

}

}