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Java (Read and write to file)


Java (Read and write to file)

By : CPelote
Date : October 28 2020, 08:00 PM
like below fixes the issue The PrintWriter only really writes when they are closed (close) or flushed (flush or maybe when it thinks it is time ;-)).
Try to use try-with-resources whenever possible, that way you do not need to think about closing/flushing a stream or writer. try-with-resources takes care that AutoClosable-implementations are closed automatically at the end of the try-block.
code :
try(
  Scanner file = new Scanner(new File("Names.txt"));
  PrintWriter pass = new PrintWriter("pass.txt");
  PrintWriter fail = new PrintWriter("fail.txt")
) {


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JAVA : read and write a file together

JAVA : read and write a file together


By : Pam Grijalva
Date : March 29 2020, 07:55 AM
I wish this help you It's far easier if you don't do two things at the same time. The best way is to run through the entire file, count all the occurrences of each string in a hash and then write out all the results into another file. Then if you need to, move the new file over the old one.
You never want to read and write to the same file at the same time. Your offsets within the file will shift everytime you make a write and the read cursor will not keep track of that.
Java application cannot write/read serialization file when installed to C:/Program Files - java.io.FileNotFoundException

Java application cannot write/read serialization file when installed to C:/Program Files - java.io.FileNotFoundException


By : David Whitten
Date : March 29 2020, 07:55 AM
it helps some times My solution was to use environment variables to get the correct directory to store application data. Here's the method I created:
code :
private String getAppDataDirectory(String subDirectory, boolean create) {

    String appDataDirectory;
    try {
        appDataDirectory = System.getenv("APPDATA"); //Windows
        //todo - could try "ALLUSERSPROFILE"
        if (appDataDirectory != null) {
            appDataDirectory += File.separator + subDirectory + File.separator;
        }
        else { //appDataDirectory is null
            appDataDirectory = System.getenv("HOME"); //Unix
            if (appDataDirectory != null) {
                appDataDirectory +=  File.separator + subDirectory + File.separator;
            }
            else { //appDataDirectory is still null
                throw new Exception("Could not access APPDATA or HOME environment variables");
            }
        }
    }
    catch(Exception e) {
        e.printStackTrace();
        appDataDirectory = "";
    }

    if (create && appDataDirectory != null && appDataDirectory.length() > 0) {
        try {
            File dir = new File(appDataDirectory);
            dir.mkdir();
        }
        catch(Exception e) {
            e.printStackTrace();
        }
    }

    //log("appDataDirectory: " + appDataDirectory);
    return appDataDirectory;
}
JAVA-Read a file in java and write them into n different files based on unique words

JAVA-Read a file in java and write them into n different files based on unique words


By : Ionis Keno
Date : March 29 2020, 07:55 AM
wish help you to fix your issue You can look String.split(String regex) and after you split the lines into ArrayLists, then you can control everything you want.
String Split
Write a java program to read from a lengthy string (using streams) and write the output to a file?

Write a java program to read from a lengthy string (using streams) and write the output to a file?


By : Maria Yu
Date : March 29 2020, 07:55 AM
help you fix your problem How can I get a lengthy String as an input using streams and how to write the output to a file ?
code :
/*

Here is another way you can perform the storage.
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;

public class WriteExample {
public static void main(String[] args) {

    FileOutputStream fop = null;
    File file;
    String content = "This is the text content";//our you can take it

    try {

        file = new File("c:/newfile.txt");//File creation at C:/
        fop = new FileOutputStream(file);

        // if file doesnt exists, then create it
        if (!file.exists()) {
            file.createNewFile();
        }

        // get the content in bytes
        byte[] contentInBytes = content.getBytes();

        fop.write(contentInBytes);
        System.out.println("Done");

    } catch (IOException e) {
        e.printStackTrace();
      }
   finally{
      if(fop!=null){
      fop.flush();
      fop.close();
   }
}
Read and Write CSV File using Java

Read and Write CSV File using Java


By : Cyrus
Date : March 29 2020, 07:55 AM
hope this fix your issue Create a class to store the header values, and store it in the list. Iterate over the list to save the results.
The currently used map can only store 2 values (which it is storing the header value (name its corresponding value)
code :
    class Headervalues {
    String[] header = new String[3];
}

public void readLogFile() throws Exception
{
    List<HeaderValues> list = new ArrayList<>();
    String currentLine = "";
    BufferedReader reader = new BufferedReader(new FileReader(file(false)));
    while ((currentLine = reader.readLine()) != null)
    {
        if (currentLine.contains("2016") && currentLine.contains("helloworld"))
        {

                String nextBlock = replaceAll(currentLine.substring(22, currentLine.length());

                String[] data = nextBlock.split(";");
                HeaderValues headerValues = new HeaderValues();
                //Assuming data.length will always be 3.
                for (int i = 0, max = data.length; i < max; i++)
                {
                    String[] d = data[i].split("=");
                    //Assuming split will always have size 2
                   headerValues.header[i] = d[1];
                }
                list.add(headerValues)
            }
        }
    }
    reader.close();
}
public void writeContentToCsv() throws Exception
{
    FileWriter writer = new FileWriter(".../file_new.csv");
    for (HeaderValues value : headerValues)
    {
        writer.append(value.header[0]).append(";").append(value.header[1]).append(";").append(value.header[2]);
    }
    writer.close();
}
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