>>408
public static void main(String[] args) throws IOException {
ArrayList[] data = new ArrayList[4];
for (int i = 0; i < 4; i++) {
String n = String.valueOf(i + 1);
BufferedReader fr = new BufferedReader(new FileReader("C:/file/txt" + n + ".txt"));
while (true) {
String line = fr.readLine();
if (line == null) break;
data[i].add(line);
}
fr.close();
}

FileWriter fw = new FileWriter("C:/file/txt0.txt");
for (int i = 0; i < 4; i++) {
fw.write((String) data[i].get(0));
}
fw.flush();
fw.close();
}