doesn't ".//d+." can determine whether a string contains number? please help.

Question about the task

Under discussion

package com.codegym.task.task19.task1923; import java.io.BufferedReader; import java.io.FileReader; import java.io.FileWriter; import java.io.BufferedWriter; /* Words with numbers */ public class Solution { public static void main(String[] args) throws Exception{ BufferedReader br = new BufferedReader(new FileReader(args[0])); String regex = ".*\\d+.*"; FileWriter fw = new FileWriter(args[1]); StringBuilder sb = new StringBuilder(); while(br.ready()) { sb.append((char)br.read()); } String[] elements = sb.toString().split(" "); StringBuilder outsb = new StringBuilder(); for(String element : elements) { if(element.matches(regex)) outsb.append(element + " "); } String out = outsb.toString(); fw.write(out.trim()); fw.close(); br.close(); } }

The main method's first parameter is file1 and the second is file2.
file1 contains lines with words separated by spaces.
Write to file2 all the words that contain numbers, for example, a1 or abc3d. Separate the words with spaces.
Close the streams.

Requirements:

The program must NOT read data from the console.
The program must read the first file's contents (use the FileReader constructor with a String parameter).
The file input stream (FileReader) must be closed.
The program should write all the words containing numbers from the first file to the second file (use FileWriter).
The file output stream (FileWriter) must be closed.

Comments (6)

Popular
New
Old

You must be signed in to leave a comment

hanumohan

Level 25 , San Jose, United States

20 May 2020, 23:40

FileReader file = new FileReader("file path for input value");
       BufferedReader bf = new BufferedReader(file);
       FileWriter write = new FileWriter("file path for output/write");

       StringBuilder sb = new StringBuilder();
       while (bf.ready()){
           String s = bf.readLine();
           String[] split = s.trim().split(" ");
           for(String temp: split){
               String regex = "(.)*(\\d)(.)*";
               Pattern pattern = Pattern.compile(regex);
               Matcher matcher = pattern.matcher(temp);
               if(matcher.matches()){
                   sb.append(temp).append(" ");
               }
           }
           String holdString = sb.toString().trim();
           write.write(holdString);
       }

       file.close();
       bf.close();
       write.close();
   }

manatsu ginn

Level 28 , Tokyo, Japan

21 May 2020, 03:21

Thanks for your reply, but I tried this text with your code, and didn't get desired result "This coo2sts one dol3lar, but this4 is twelve. The variable 1is called file1. 110 is a number." The output is "coo2sts dol3lar, this4 1is", file1.\n110 didn't show up.

Thomas

Level 41 , Bayreuth, Germany

20 May 2020, 10:51

you use wrong slashes for escaping, and detecting just one digit would be enough, so the + is redundant

manatsu ginn

Level 28 , Tokyo, Japan

21 May 2020, 03:24

Thanks for your reply, Could you please paste a copy of "requirement-passed" code please? Thanks.

Thomas

Level 41 , Bayreuth, Germany

21 May 2020, 07:09

without pattern matcher

//create reader and writer streams
String inputFile = args[0];
String outputFile = args[1];
BufferedReader reader = new BufferedReader(new FileReader(inputFile));
BufferedWriter writer = new BufferedWriter(new FileWriter(outputFile));

//read inputFile into StringBuilder, instead of line break at line end, add space
StringBuilder data = new StringBuilder();
while (reader.ready())
    data.append(reader.readLine()+" ");
reader.close();

//split into parts using space(s) as delimiter
String[] parts = data.toString().split("\\s+");

//loop through split array, if entry matches 0-x anything, number, 0x -anything, add to StringBuilder with a space
data = new StringBuilder();
for (String s : parts) {
    if (s.matches(".*\\d.*"))
        data.append(s).append(" ");
}

//to get rid of the space at the end of StringBuilder object, convert to String and trim
String output = data.toString().trim();
writer.write(output);
writer.close();

manatsu ginn

Level 28 , Tokyo, Japan

21 May 2020, 08:01

Oh my god, thanks a lot. I think the problem my code has is that it picks "12d\nx1" out as one word rather than "12d" and "x1".

doesn't ".*//d+.*" can determine whether a string contains number? please help.

doesn't ".//d+." can determine whether a string contains number? please help.