Develop Reference

Unable to copy txt file over to arraylist and into file

I am attempting to add this large txt file into an array list then sort the data. Then put 15000 lines in various temp files. I am unable to put the data into each file. Here is my code:
package bigfilesorter2;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Scanner;
public class bigfilesorter2 {
public static final int NUM_LINES = 15000;
public static void main(String args[]) throws IOException {
FileReader fileReader = new FileReader("Aesop_Shakespeare_Shelley_Twain.txt");
BufferedReader br = new BufferedReader(fileReader);
ArrayList<String> arraylist = readingfile(br);
//System.out.println(arraylist);
makingfiles(br, arraylist);
}
public static void makingfiles(BufferedReader br, ArrayList<String> arraylist) throws IOException {
int start = 0;
int end = 15000;
for(int i = 0; i < 20; i++) {
File file = new File("/Users/domlanza/desktop/testing/Filee"+i+".txt");
FileWriter fw = new FileWriter(file);
BufferedWriter bw = new BufferedWriter(fw);
for(;start <= end; start++){
bw.write(arraylist.get(start));
bw.newLine();
}
bw.flush();
bw.close();
fw.close();
start = end + 1;
end += 15000;
}
}
public static ArrayList<String> readingfile(BufferedReader br) throws FileNotFoundException, IOException {
//Read in file
Scanner s = new Scanner(new File("Aesop_Shakespeare_Shelley_Twain.txt"));
int count = 0;
ArrayList<String> arraylist = new ArrayList<String>();
while (s.hasNext()) {
count++;
arraylist.add(s.nextLine());
}
//} catch (IOException e) {e.printStackTrace();}
Collections.sort(arraylist);
//System.out.println(arraylist);
return arraylist;
}
}
Any help would be appreciated. the commas were just the file being sorted..................
"it looks like your post is mostly code"

You need to create a list of sublists where each sublist holds 15000 lines. Given below is the complete code:
import java.io.BufferedReader;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
public class BigFileSorter {
public static final int NUM_LINES = 15000;
public static final int NUM_FILES = 20;
public static void main(String args[]) throws IOException {
FileReader fileReader = new FileReader("file.txt");
BufferedReader br = new BufferedReader(fileReader);
ArrayList<ArrayList<String>> list = readingfile(br);
makingfiles(br, list);
}
public static void makingfiles(BufferedReader br, ArrayList<ArrayList<String>> list) throws IOException {
if (list != null) {
for (int i = 0; i < NUM_FILES; i++) {
File file = new File("Filee" + i + ".txt");
FileWriter fw = new FileWriter(file);
ArrayList<String> subList = list.get(i);
for (String str : subList) {
fw.write(str + System.lineSeparator());
}
fw.close();
}
}
}
public static ArrayList<ArrayList<String>> readingfile(BufferedReader br)
throws FileNotFoundException, IOException {
ArrayList<ArrayList<String>> list = new ArrayList<ArrayList<String>>();
ArrayList<String> subList;
String line;
try {
for (int i = 0; i < NUM_FILES; i++) {
subList = new ArrayList<String>();
for (int j = 0; j < NUM_LINES; j++) {
line = br.readLine();
if (line == null) {
break;
}
subList.add(line);
}
Collections.sort(subList);
list.add(subList);
}
} catch (IOException e) {
e.printStackTrace();
} finally {
br.close();
}
return list;
}
}
Feel free to comment in case of any doubt.

Maybe something like this as an inner for loop in your makefiles method.
// outside of the for loops
int start = 0;
int end = 15000;
// inner for loop
for(;start <= end; start++){
bw.write(arraylist.get(start));
bw.newline();
}
// end of outer for loop
start = end + 1;
end += 15000;
So complete method:
public static void makingfiles(BufferedReader br, ArrayList<String> arraylist) throws IOException {
int start = 0;
int end = 15000;
for(int i = 0; i < 20; i++) {
File file = new File("/Users/domlanza/desktop/testing/Filee"+i+".txt");
FileWriter fw = new FileWriter(file);
BufferedWriter bw = new BufferedWriter(fw);
for(;start <= end; start++){
bw.write(arraylist.get(start));
bw.newline();
}
bw.flush();
bw.close();
fw.close()
start = end + 1;
end += 15000;
}
}
Should work for what you asked in the comment, but you still have to change your read method so that it reads all the lines in one arraylist

Read string arrays from file

I have this code:
public static void write() throws IOException{
ObjectOutputStream out = new ObjectOutputStream(
new FileOutputStream("ips.txt")
);
for ( int i = 0; i < Main.ipList.length; i++){
out.writeObject(ipList[i]);
}
out.flush();
out.close();
}
Which writes the string array to a text file:
static String[] ipList = {"127.0.0.1", "173.57.51.111"};
I was wondering how it would be possible to read the text file and edit the ipList with the new ips.

If you want to write String objects to a file, it's better to use a FileWriter instead of an ObjectOutputStream. Similarly, use a FileReader to read from the file. See https://docs.oracle.com/javase/tutorial/essential/io/charstreams.html for how to use these Reader objects.
ObjectOutputStream is usually suitable for writing more complex objects that implement the java.io.Serializable interface.
Here's an example:
BufferedReader inputStream = null;
List<String> ipList = new ArrayList<>();
try {
inputStream = new BufferedReader(new FileReader("ips.txt"));
String l;
while ((l = inputStream.readLine()) != null) {
ipList.add(l);
}
} finally {
if (inputStream != null) {
inputStream.close();
}
}
// get an array from the ArrayList
ipArray = ipList.toArray(new String[ipList.size()]);

You can try something like this
package a;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectOutputStream;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
public class A {
static String[] ipList = { "127.0.0.1", "173.57.51.111" };
public static void main(String[] args) {
try {
write();
update();
} catch (IOException e) {
System.err.println(e);
}
Arrays.asList(ipList).stream().forEach(System.out::println);
}
// Your method
public static void write() throws IOException {
ObjectOutputStream out = new ObjectOutputStream(new FileOutputStream("ips.txt"));
for (int i = 0; i < A.ipList.length; i++) {
out.writeObject(ipList[i]);
}
out.flush();
out.close();
}
public static void update() throws IOException {
List<String> lines = Files.readAllLines(Paths.get(".", "newIps.txt"));
List<String> newIps = new ArrayList<>();
newIps.addAll(Arrays.asList(ipList));
newIps.addAll(lines);
ipList = newIps.toArray(ipList);
}
}
The content of the newIps.txt file is
0.0.0.0
192.168.1.1
The output of the program is
127.0.0.1
173.57.51.111
0.0.0.0
192.168.1.1
Note that Arrays.asList(ipList) returns a bridge list over the array (any changes to the list will be visible for array), so we do a putAll

FileNotFound exception while files already exist

this code couldn't find the files that the buffered reader is supposed to read from it and i have the files in the src folder in eclipse project and it still doesn't read from file so does anybody have any idea about what the problem is.
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.math.*;
import java.util.ArrayList;
public class Encrypt {
public static ArrayList<String> data = new ArrayList<String>();
public static BigInteger [] keys = new BigInteger[3];
public static BigInteger n;
public static double e;
public static BigInteger d;
public static String line;
public static String result;
public static String [] temp;
public static BigInteger tempVar;
public static BigInteger tempResult;
public static int tempVar2;
public static void encryption(ArrayList<String> data) throws IOException{
for (int i = 0; i<data.size(); i++){
if(data.get(i)!= null){
temp = new String[data.get(i).split(" ").length];
temp = data.get(i).split(" ");
for(int j = 0; j<temp.length;j++){
for (int k = 0; k< temp[j].length(); k++){
tempVar2 = (int)temp[j].charAt(k);
tempVar=BigInteger.valueOf((long)Math.pow(tempVar2,e));
tempResult = (tempVar.remainder(n));
result =""+ tempResult;
LogEncrypt(result);
}
}
}
}
}
public static void read() throws IOException{
try {
BufferedReader br = new BufferedReader(new FileReader("plainText.txt"));
System.out.println(br.ready());
while ((line = br.readLine()) != null) {
data.add(br.readLine());
}
System.out.println("done with text");
} catch (FileNotFoundException e) {
System.out.println("please add the text file");
e.printStackTrace();
}
try {
BufferedReader ba = new BufferedReader(new FileReader("Key.txt"));
System.out.println(ba.ready());
int i =0;
while ((line = ba.readLine()) != null) {
keys[i] = new BigInteger(ba.readLine());
i++;
}
n = keys[0];
e = keys[1].doubleValue();
d = keys[2];
System.out.println("done with key");
} catch (FileNotFoundException e) {
System.out.println("please add the key file");
e.printStackTrace();
}
}
public static void LogEncrypt(String result) throws IOException {
BufferedWriter out = new BufferedWriter(new FileWriter("output.txt"));
try {
out.write(result);
out.newLine();
} catch(IOException e1) {
System.out.println("Error during reading/writing");
} finally {
out.close();
}
}
public static void main(String[]args) throws IOException{
read();
encryption(data);
}
}

Put the file outside of the src, or at least add "src/" to the file location

Java: Make a void-method out of this class (textfile changer)

What I want to do: My class copytest reads a textfile, edits one character and save this new file in a new directory. I want to program a void-method out of it, which does exactly the same and can then be used the following way:
copy(String "C:\\Old.txt", String "C:\\New.txt", int 1, int 1)
Now copy does exactly the same as my old class copytest, it reads the old file, edits it and saves it.
My first idea was to have two files as the first to arguments, but this is obviously impossible. My new idea is to give the method two strings of the wanted directories of the old and the new file. It still doesn't work. I hope, you understand, what I want to do and how to solve this problem.
Old class code (works):
import java.io.*;
import java.util.Scanner;
public class copytest {
public static void main(String[] args) throws Exception {
readFile();
}
public static void readFile() throws Exception {
// Location of file to read
File file = new File("...old.txt");
Scanner scanner = new Scanner(file);
int lineNumber=1;
int charNumber=1;
String wantedChar="r";
int i=0;
while (scanner.hasNextLine()) {
String line = scanner.nextLine();
if (i == lineNumber+2) {
if (line.length() >= charNumber) {
line = line.substring(0,charNumber-1) + wantedChar + line.substring(charNumber);
}
}
writeFile(line);
i++;
}
scanner.close();
System.out.println("File copied.");
}
public static void writeFile(String copyText) throws Exception {
String newLine = System.getProperty("line.separator");
// Location of file to output
Writer output = null;
File file = new File("...new.txt");
output = new BufferedWriter(new FileWriter(file, true));
output.write(copyText);
output.write(newLine);
output.close();
}
}
New void code (first try with file as argument):
public void copy(file old, file new, int x, int y) {
public static void readFile() throws Exception {
Scanner scanner = new Scanner(old);
int lineNumber=y;
int charNumber=x;
String wantedChar="r";
int i=0;
while (scanner.hasNextLine()) {
String line = scanner.nextLine();
if (i == lineNumber+2) {
if (line.length() >= charNumber) {
line = line.substring(0,charNumber-1) + wantedChar + line.substring(charNumber);
}
}
writeFile(line);
i++;
}
scanner.close();
System.out.println("File copied.");
}
public static void writeFile(String copyText) throws Exception {
String newLine = System.getProperty("line.separator");
// Location of file to output
Writer output = null;
File file = new File(new.getPath());
output = new BufferedWriter(new FileWriter(file, true));
output.write(copyText);
output.write(newLine);
output.close();
}
readFile();
}
New try with strings as argument, but still doesn't work:
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileWriter;
import java.io.Writer;
import java.util.Scanner;
public class copytestnew {
public void copy(String old, String newone, int x, int y) {
// Location of file to read
File file = new File(old);
Scanner scanner = new Scanner(file);
int lineNumber=y;
int charNumber=x;
String wantedChar="r";
int i=0;
while (scanner.hasNextLine()) {
String line = scanner.nextLine();
if (i == lineNumber+2) {
if (line.length() >= charNumber) {
line = line.substring(0,charNumber-1) + wantedChar + line.substring(charNumber);
}
}
String newLine = System.getProperty("line.separator");
// Location of file to output
Writer output = null;
File file2 = new File(newone);
output = new BufferedWriter(new FileWriter(file2, true));
output.write(line);
output.write(newLine);
output.close();
i++;
}
scanner.close();
System.out.println("File copied");
}
}

I remember you! I answeared you last time on how to replace the char at one of the lines.
First, change the decleration to
public static void copy(String old, String newone, int x, int y) throws IOException {
NOTICE the throws statment!
And now when you want to call this method you should use it inside a try-catch block or declear that you throwing exception same as you did at the copy function.

public void copy(file old, file new, int x, int y) {
public static void readFile() throws Exception {
You're defining a function inside a method. As all functions in java are methods (static or non-static), this is not permitted. Try this:
class IDontKnowHowToNameIt {
public static void copy(file old, file new, int x, int y) {
//...
// call readFile from here
// ...
}
private static void readFile() throws Exception {
//...
}
}

How to use data stored in a variable located in a seperate file?

I have two files. One file counts the number of listed events I have in a text file and stores the number of events into the variable "count". I want to then use the value in this variable to do computation in a second file. How do I do this? Do I have to create an object of the class in my first file and then reference it? I need an example please, I cannot seem to get this to work. Here is what I have tried.
My first file:
import java.util.*;
import java.io.*;
public class EventCounter {
public static void main (String [] args) throws IOException{
Scanner file = new Scanner(new File("event.txt"));
int count = 0;
while (file.hasNextLine()) {
count++;
file.nextLine();
}
System.out.println(count); //test
}
}
My Second file:
import java.io.IOException;
import java.io.FileReader;
import java.io.BufferedReader;
public class ReadEventFile {
private String path;
public ReadEventFile(String file) {
path = file;
}
public String[] OpenFile() throws IOException {
FileReader fr = new FileReader(path);
BufferedReader textReader = new BufferedReader(fr);
EventCounter method = new EventCounter(); //make object?
String[] dataTable = new String[count];
int i;
for (i=0; i<count; i++) { //Why count does not exist?
}
My second file does not know that count is a variable from my first file :-(

You seem to have your process flow backwards. The class with the main method will be created and run by the JVM - therefore it's your entry point.
Your ReadEventFile class therefore needs to be told the count when it is created. Simply add it to the constructor:
public static class ReadEventFile {
private final File eventFile;
private final int count;
public ReadEventFile(final int count, final File eventFile) {
this.eventFile = eventFile;
this.count = count;
}
public String[] openFile() throws IOException {
String[] dataTable = new String[count];
int i;
for (i = 0; i < count; i++) {
}
return dataTable;
}
}
Now your EventCounter needs to create a ReadEventFile instance once it knows the count and call the openFile method on it:
public static void main(String[] args) throws IOException {
final File eventFile = new File("event.txt");
int count = 0;
try (Scanner file = new Scanner(eventFile)) {
while (file.hasNextLine()) {
count++;
file.nextLine();
}
}
final ReadEventFile readEventFile = new ReadEventFile(count, eventFile);
final String[] dataTable = readEventFile.openFile();
}
The ReadEventFile does it's work and then returns the String[] back to your EventCounter.
You don't close any of your resources when you are done with them. This is asking for trouble. I have added a Java 7 try-with-resources around your Scanner in the EventCounter.
The design of this program does seem a little odd. There is no logical reason why the EventCounter should be the entry point to the application. I would recommend you create a BootStrap class that holds the main method and is the entry point that then calls both the EventCounter and the ReadEventFile.
Further, the openFile method on the ReadEventFile class isn't well named - it does more than that. Maybe processEventFile or something along those lines would be more appropriate.

your first Program
package farzi;
import java.util.*;
import java.io.*;
public class EventCounter {
public static void main (String [] args) throws IOException
{
EventCounter object = new EventCounter();
System.out.println(object.returnCount());
}
public int returnCount() throws FileNotFoundException
{
Scanner file = new Scanner(new File("event.txt"));
int count = 0;
while (file.hasNextLine()) {
count++;
file.nextLine();
}
System.out.println(count); //test
return count;
}
}
your second program
package farzi;
import java.io.File;
import java.io.IOException;
import java.io.FileReader;
import java.io.BufferedReader;
public class ReadEventFile
{
private String path;
public ReadEventFile(String file)
{
String path = file;
}
public String[] OpenFile() throws IOException {
EventCounter eventCounterObject = new EventCounter();
int countLocal = eventCounterObject.returnCount();
FileReader fr = new FileReader(path);
BufferedReader textReader = new BufferedReader(fr);
EventCounter method = new EventCounter(); //make object?
String[] dataTable = new String[countLocal];
int i;
String[] textData = null;
for (i=0; i<countLocal; i++) { //Why count does not exist?
textData[i] = textReader.readLine();
}
return textData;
}
}