возможно не полностью понял условие
package com.javarush.task.task19.task1923;
/*
Слова с цифрами
*/
import java.io.*;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class Solution {
public static void main(String[] args) throws IOException {
FileReader fr = new FileReader(args[0]);
BufferedReader br = new BufferedReader(fr);
FileWriter fw = new FileWriter(args[1],true);
BufferedWriter bw = new BufferedWriter(fw);
String buf_Line = br.readLine();
while (buf_Line!=null){
Pattern pattern = Pattern.compile("\\d*[0-9]\\d*");
String lineArr [] = buf_Line.split(" ");
for (int i = 0; i <lineArr.length ; i++) {
Matcher matcher = pattern.matcher(lineArr[i]);
while (matcher.find()) {
//System.out.println(lineArr[i]);
bw.write(lineArr[i]+" ");
}
}
buf_Line = br.readLine();
}
fr.close();
br.close();
bw.close();
}
}