读写txt文件

Question

I am working on a java program where:

program reads in two txt files(txt1 & txt2) it then prints out the txt1 and txt2 to txt3 alternating "lines" from each txt1 and txt2.

example: txt1 =

this is first is one

txt2= that was two

txt3 should be: this is first that is was one two

I am not sure what I am missing...any help would be appreciated.

code:

package combine;

import java.io.*;
import java.util.*;
import java.nio.file.*;

public class Main{

public static void main(String[] args) throws IOException{
   String targetDir = "C:\\Parts";
   String outputFile = "C:\\Parts\\complete\\TheRavensGreenEggs.txt";

   File dir = new File(targetDir);
   File[] files = dir.listFiles(new FilenameFilter() {
     // Only import "txt" files
     @Override
     public boolean accept(File dir, String name) {
        return name.toLowerCase().endsWith(".txt");
    }
});

// Reads all "txt" file lines into a List
List<String> inputFileLines = new ArrayList<>();{
for (File file : files) {
    inputFileLines.addAll(Files.readAllLines(Paths.get(file.getAbsolutePath())));
}}


// Writes the List to the console
for (String line : inputFileLines) {
    System.out.println(line);
}

// Writes the List to a single "TheRavensGreenEggs.txt" file
Files.write(Paths.get(outputFile), inputFileLines, StandardOpenOption.CREATE);
}}

Answer 1

I am working on a java program where:

program reads in two txt files(txt1 & txt2) it then prints out the txt1 and txt2 to txt3 alternating "lines" from each txt1 and txt2.

example: txt1 =

this is first is one

txt2= that was two

txt3 should be: this is first that is was one two

I am not sure what I am missing...any help would be appreciated.

code:

package combine;

import java.io.*;
import java.util.*;
import java.nio.file.*;

public class Main{

public static void main(String[] args) throws IOException{
   String targetDir = "C:\\Parts";
   String outputFile = "C:\\Parts\\complete\\TheRavensGreenEggs.txt";

   File dir = new File(targetDir);
   File[] files = dir.listFiles(new FilenameFilter() {
     // Only import "txt" files
     @Override
     public boolean accept(File dir, String name) {
        return name.toLowerCase().endsWith(".txt");
    }
});

// Reads all "txt" file lines into a List
List<String> inputFileLines = new ArrayList<>();{
for (File file : files) {
    inputFileLines.addAll(Files.readAllLines(Paths.get(file.getAbsolutePath())));
}}


// Writes the List to the console
for (String line : inputFileLines) {
    System.out.println(line);
}

// Writes the List to a single "TheRavensGreenEggs.txt" file
Files.write(Paths.get(outputFile), inputFileLines, StandardOpenOption.CREATE);
}}

Answer 2

Use List<String> and java.nio like this:

public static void main(String[] args) {
    // define the input paths and the output path
    Path file01Path = Paths.get("Y:\\our\\path\\to\\file_01.txt");
    Path file02Path = Paths.get("Y:\\our\\path\\to\\file_02.txt");
    Path outputPath = Paths.get("Y:\\our\\path\\to\\result.txt");
    // provide a list for the alternating lines
    List<String> resultLines = new ArrayList<>();

    try {
        // read the lines of both files and get them as lists of Strings
        List<String> linesOfFile01 = Files.readAllLines(file01Path);
        List<String> linesOfFile02 = Files.readAllLines(file02Path);
        // find a common border for the iteration: the size of the bigger list
        int maxSize = (linesOfFile01.size() >= linesOfFile02.size())
                ? linesOfFile01.size() : linesOfFile02.size();

        // then loop and store the lines (if there are any) in a certain order
        for (int i = 0; i < maxSize; i++) {
            // lines of file 01 first
            if (i < linesOfFile01.size()) {
                resultLines.add(linesOfFile01.get(i));
            }
            // lines of file 02 second
            if (i < linesOfFile02.size()) {
                resultLines.add(linesOfFile02.get(i));
            }
        }

        // after all, write the content to the result path
        Files.write(outputPath,
                resultLines,
                Charset.defaultCharset(),
                StandardOpenOption.CREATE_NEW);
    } catch (IOException e) {
        System.err.println("Some files system operation failed:");
        e.printStackTrace();
    }
}

Answer 3

This approach still uses most of your original code.

The idea is to keep separate lists of lines for each file, and then loop over the total amount of lines, switching to a different list on each iteration.

If the files have a different amount of lines in them, you will need to add some logic (otherwise you will get an IndexOutOfBounds error when accessing a line number that does not exist)

package combine;

import java.io.*;
import java.util.*;
import java.nio.file.*;

public class Main{

   public static void main(String[] args) throws IOException{

       String targetDir = "C:\\Parts";
       String outputFile = "C:\\Parts\\complete\\TheRavensGreenEggs.txt";

       File dir = new File(targetDir);
       File[] files = dir.listFiles(new FilenameFilter() {
           // Only import "txt" files
           @Override
           public boolean accept(File dir, String name) {
               return name.toLowerCase().endsWith(".txt");
           }
       });

       // Reads all "txt" file lines into a List
       List<List<String>> inputFileLines = new ArrayList<>();{
       for (File file : files){ 
       inputFileLines.add(Files.readAllLines(Paths.get(file.getAbsolutePath()))) 
       }


       // Writes the List to the console
       int n = inputFileLines.size();  // number of files
       int m = inputFileLines.get(0).size() * n; // number of lines in total
       for (int i=0;i<m;i++) {
       System.out.println(inputFileLines.get(i % n).get(i / n));
       }

       // Writes the List to a single "TheRavensGreenEggs.txt" file
       // should be the same as printing to console
    }
}