CODEWITHSUNDEEP
java
Diana Choate
Diana Choate

Reputation: 11

Read and Write with java from one file to another

How do I read the following information from a txt file and write just the numbers to another text file using Java? I have it displaying to the console but it will not write to the file also.

Jones 369218658389641
Smith 6011781008881301
Wayne 5551066751345482
Wines 4809134775860430
Biggie 9925689541232325
Luke 7586425896325410
Brandy 4388576018410707
Ryan 2458912425860439

import java.util.Scanner;
import java.io.File;

public class test {
public static void main(String[] args) throws Exception {
    // Create a File instance
    java.io.File file = new java.io.File("accounts.txt");
    // Create a Scanner for the file
    Scanner input = new Scanner(file);
    // Read data from a file
    while (input.hasNext()) {
        String accountName = input.next();
        Long cardNumber = input.nextLong();
//this is where I want to write just the numbers to a file called cardnums.txt          
        file = new java.io.File("cardnums.txt"); 
        java.io.PrintWriter output = new java.io.PrintWriter(file); 
        output.println(cardNumber);
        System.out.println(cardNumber);
    }
    // Close the file
    input.close();

}
}

I got it now.

import java.util.Scanner;
import java.io.File;

public class test {
public static void main(String[] args) throws Exception {
    // Create a File instance
    java.io.File file = new java.io.File("accounts.txt");
    // Create a Scanner for the file
    Scanner input = new Scanner(file);
    // Read data from a file
    file = new java.io.File("cardnums.txt"); 
    java.io.PrintWriter output = new java.io.PrintWriter(file); 
    while (input.hasNext()) {
        String accountName = input.next();
        Long cardNumber = input.nextLong();
//this is where I want to write just the numbers to a file called credit.txt            
        output.println(cardNumber);
        System.out.println(cardNumber);
    }
    // Close the file
    input.close();
    output.flush();
    output.close();
}
}

Upvotes: 0

Views: 937

Answers (2)

Bohemian
Bohemian

Reputation: 425418

Here's a 1-liner:

Files.write(Paths.get("cardnums.txt"), () ->
   Files.lines(Paths.get("accounts.txt"))
    .map(s -> s.replaceAll("\\D", ""))
    .collect(toList())
    .iterator());

Disclaimer: Code may not compile or work as it was thumbed in on my phone (but there's a reasonable chance it will work)

Upvotes: 0

Naruto
Naruto

Reputation: 4329

    java.io.PrintWriter output = new java.io.PrintWriter(file);

First of all why are you everytime calling this in loop with same filename?

Secondly, once you define it outside loop,

Call flush() on outputstream object and close if not null (preferabbly in finally block) after loop. 

if(output!=null) {
    output.flush();
    output.close();
}

Upvotes: 1

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