Here's example:
public static void main (String[] args){
String path = "C:\\Users\\Charbel\\Desktop\\Dictionary.txt";
String temppath = "C:\\Users\\Charbel\\Desktop\\temp.txt";
File file = new File(path);
File tempfile = new File(temppath);
int numl = search("x");
int countL = 0;
String line;
try {
BufferedReader bf = new BufferedReader(new FileReader(path));
BufferedWriter bw = new BufferedWriter(new FileWriter(temppath));
while (( line = bf.readLine()) != null)
{
if(countL != numl){
bw.write(line);
bw.newLine();
}
countL++;
}
bf.close();
bw.close();
file.delete();
boolean successful = tempfile.renameTo(file);
System.out.println(successful);
}
catch (IOException e) {
System.out.println("IO Error Occurred: " + e.toString());
}
}
public static int search(String name)
{
String path = "C:\\Users\\Charbel\\Desktop\\Dictionary.txt";
int countL = 0;
String line;
try {
BufferedReader bf = new BufferedReader(new FileReader(path));
while (( line = bf.readLine()) != null)
{
int indexfound = line.indexOf(name);
if (indexfound == 0) {
return countL;
}
countL++;
}
bf.close();
}
catch (IOException e) {
System.out.println("IO Error Occurred: " + e.toString());
}
return -1;
}
}
Hello there .. i am trying to read the line of a specific string in a text file , get the number of its line , then copy all the data in the file to another text file except the line of the string
the code is sometimes working 100% and sometimes no ; I go to my desktop I see both files the temp and the original one without deleting and renaming it
i think i have a problem in deleting the file what do you think coders ?
Because when the search method find name(actually "x"),don't reach the line bf.close(), so bf is still opened and file.delete() fails.
So, you need to modify the search method to the below:
public static int search(String name) {
String path = "C:\\Users\\Charbel\\Desktop\\Dictionary.txt";
int countL = 0;
String line;
BufferedReader bf = null;
try {
bf = new BufferedReader(new FileReader(path));
while (( line = bf.readLine()) != null)
{
int indexfound = line.indexOf(name);
if (indexfound == 0) {
return countL;
}
countL++;
}
}
catch (IOException e) {
System.out.println("IO Error Occurred: " + e.toString());
}
finally {
if(bf != null) {
try {
bf.close();
}
catch(IOException ignored) {}
}
}
return -1;
}
Related
I want to create a method that reads from a file, then creates a file which will then write a certain subset of what was read from but I keep getting a null pointer exception at output.write(line) and I am not sure why?
public void readCreateThenWriteTo(String file, String startRowCount, String totalRowCount) {
BufferedReader br = null;
File newFile = null;
BufferedWriter output = null;
StringBuilder sb = null;
int startRowCountInt = Integer.parseInt(startRowCount);
int totalRowCountInt = Integer.parseInt(totalRowCount);
try {
br = new BufferedReader(new FileReader(file));
sb = new StringBuilder();
newFile = new File("hiya.txt");
output = new BufferedWriter(new FileWriter(newFile));
String line = "";
int counter = 0;
while (line != null) {
line = br.readLine();
if (startRowCountInt <= counter && counter <= totalRowCountInt) {
System.out.println(line);
output.write(line);
}
counter++;
}
} catch (IOException e) {
// TODO Auto-generated catch block
LOGGER.info("File was not found.");
e.printStackTrace();
} finally {
// Should update to Java 7 in order to use try with resources and then this whole finally block can be removed.
try {
if ( br != null ) {
br.close();
}
if ( output != null ) {
output.close();
}
} catch (IOException e) {
// TODO Auto-generated catch block
LOGGER.info("Couldn't close BufferReader.");
e.printStackTrace();
}
}
}
You need to check the result of readLine() before you enter the loop:
while ((line = br.readLine()) != null) {
if (startRowCountInt <= counter && counter <= totalRowCountInt) {
System.out.println(line);
output.write(line);
}
counter++;
}
So Im working of reading a file containing appointments that I wrote to earlier in my code. I want to sift through the text file and find appointments on a certain date and add them to an ArrayList but when the BufferedReader goes through it, it skips ever other line... Heres my code
public ArrayList<String> read(int checkDay, int checkMonth, int checkYear) {
ArrayList<String> events = new ArrayList<String>();
BufferedReader in = null;
String read;
try {
in = new BufferedReader(new FileReader("calendar.txt"));
while ((read = in.readLine()) != null) {
read = in.readLine();
String[] split = read.split(",");
System.out.println(read);
if (split[1].equals(Integer.toString(checkDay)) && split[2].equals(Integer.toString(checkMonth)) && split[3].equals(Integer.toString(checkYear))) {
events.add(split[0] + " : " + split[1] + "/" + split[2] + "/" + split[3]);
}
}
} catch (IOException e) {
System.out.println("There was a problem: " + e);
e.printStackTrace();
} finally {
try {
in.close();
} catch (Exception e) {
}
}
return events;
}
You are reading the line twice..
while ((read = in.readLine()) != null) { // here
read = in.readLine(); // and here
You have error here:
while ((read = in.readLine()) != null)
read = in.readLine();
you should keep the read = in.readLine() in the while. and remove the other line.
pl try this
you r using "read = in.readLine())" two times in while loop that why it is skiping the lomes
public ArrayList<String> read(int checkDay, int checkMonth, int checkYear) {
ArrayList<String> events = new ArrayList<String>();
BufferedReader in = null;
String read;
try {
in = new BufferedReader(new FileReader("calendar.txt"));
while ((read = in.readLine()) != null) {
String[] split = read.split(",");
System.out.println(read);
if (split[0].equals(Integer.toString(checkDay)) && split[1].equals(Integer.toString(checkMonth)) && split[2].equals(Integer.toString(checkYear))) {
events.add(split[0] + " : " + split[1] + "/" + split[2] + "/" + split[3]);
}
}
} catch (IOException e) {
System.out.println("There was a problem: " + e);
e.printStackTrace();
} finally {
try {
in.close();
} catch (Exception e) {
}
}
return events;
I'm having a problem with reading and writing arraylist to a text file. Specifically with reading. What I'm trying to do is read from a text file and transfer it to an array list. After which i would edit the list and write it back to the text file. I think I go the writing done but not the reading. I've tried reading several similar questions here but cant seem to inject it into my code.
Reading code
public void read(List<AddressBook> addToList){
BufferedReader br = null;
try {
String currentLine= "";
br = new BufferedReader(new FileReader("bank_account.csv"));//file na gusto mo basahin
while ((currentLine = br.readLine()) != null) {
System.out.println(currentLine); // print per line
for (AddressBook read : addToList) {
br.read(read.getName() + read.getAddress() + read.getTelNum() + read.getEmailAdd());
addToList.add(read);
} }
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
if (br != null)
{
br.close();
}
} catch (IOException ex) {
ex.printStackTrace();
}
}
}
}
Here's what I've done with the write
public void write(List<AddressBook> addToList) {
try {
File file = new File("bank_account.csv"); //file
// if file doesnt exists, then create it
if (!file.exists()) {
file.createNewFile();
}
//FileWriter fw = new FileWriter(file.getAbsoluteFile());
FileWriter fw = new FileWriter(file.getAbsoluteFile(), true);
BufferedWriter bw = new BufferedWriter(fw);
for (AddressBook write : addToList) {
bw.write(write.getName() + "," + write.getAddress() + "," + write.getTelNum() + "," + write.getEmailAdd());
bw.newLine();
}
bw.close();
} catch (IOException e) {
e.printStackTrace();
}
}
while ((currentLine = br.readLine()) != null) {
System.out.println(currentLine); // print per line
for (AddressBook read : addToList) {
br.read(read.getName() + read.getAddress() + read.getTelNum() + read.getEmailAdd());
addToList.add(read);
}
}
I bet in there you will need to do something like:
reading each line
parsing it (each line is a CSV)
creating a new AddressBook object with all that info
add it to the collection
The code for that will look like:
while ((currentLine = br.readLine()) != null) {
System.out.println(currentLine); // print per line
String[] splitted = currentLine.split(",");
AddressBook address = new AddressBook(splitted[0], splitted[1], splitted[2], splitted[3]);
addToList.add(address);
}
Of course there are things you will need to check and validate, but that is roughtly it.
Maybe you need read method like this.
public void read() {
List<AddressBook> addToList =new ArrayList<AddressBook>();
BufferedReader br = null;
try {
String currentLine= "";
br = new BufferedReader(new FileReader("bank_account.csv"));//file na gusto mo basahin
while ((currentLine = br.readLine()) != null) {
System.out.println(currentLine); // print per line
// for (AddressBook read : addToList) {
String[] split =currentLine.split(",");
AddressBook read = new AddressBook();
read.setName(split[0]);
read.setAddress(split[1]);
read.setTelNum(split[2]);
read.setEmailAdd(split[3]);
// br.read(read.getName() + read.getAddress() + read.getTelNum() + read.getEmailAdd());
addToList.add(read);
// }
}
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
if (br != null)
{
br.close();
}
} catch (IOException ex) {
ex.printStackTrace();
}
}
}
I have a text file with more than 20,000 lines and i need to extract specific line from it. The output of this program is completely blank file.
There are 20,000 lines in the txt file and this ISDN line keeps on repeating lots of time each with different value. My text file contains following data.
RecordType=0(MOC)
sequenceNumber=456456456
callingIMSI=73454353911
callingIMEI=85346344
callingNumber
AddInd=H45345'1
NumPlan=H34634'2
ISDN=94634564366 // Need to extract this "ISDN" line only
public String readTextFile(String fileName) {
String returnValue = "";
FileReader file = null;
String line = "";
String line2 = "";
try {
file = new FileReader(fileName);
BufferedReader reader = new BufferedReader(file);
while ((line = reader.readLine()) != null) {
// extract logic starts here
if (line.startsWith("ISDN") == true) {
System.out.println("hello");
returnValue += line + "\n";
}
}
} catch (FileNotFoundException e) {
throw new RuntimeException("File not found");
} finally {
if (file != null) {
try {
file.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
return returnValue;
}
We will assume that you use Java 7, since this is 2014.
Here is a method which will return a List<String> where each element is an ISDN:
private static final Pattern ISDN = Pattern.compile("ISDN=(.*)");
// ...
public List<String> getISDNsFromFile(final String fileName)
throws IOException
{
final Path path = Paths.get(fileName);
final List<String> ret = new ArrayList<>();
Matcher m;
String line;
try (
final BufferedReader reader
= Files.newBufferedReader(path, StandardCharsets.UTF_8);
) {
while ((line = reader.readLine()) != null) {
m = ISDN.matcher(line);
if (m.matches())
ret.add(m.group(1));
}
}
return ret;
}
How to print lines from a file that contain a specific word using java ?
Want to create a simple utility that allows to find a word in a file and prints the complete line in which given word is present.
I have done this much to count the occurence but don't knoe hoe to print the line containing it...
import java.io.*;
public class SearchThe {
public static void main(String args[])
{
try
{
String stringSearch = "System";
BufferedReader bf = new BufferedReader(new FileReader("d:/sh/test.txt"));
int linecount = 0;
String line;
System.out.println("Searching for " + stringSearch + " in file...");
while (( line = bf.readLine()) != null)
{
linecount++;
int indexfound = line.indexOf(stringSearch);
if (indexfound > -1)
{
System.out.println("Word is at position " + indexfound + " on line " + linecount);
}
}
bf.close();
}
catch (IOException e)
{
System.out.println("IO Error Occurred: " + e.toString());
}
}
}
Suppose you are reading from a file named file1.txt Then you can use the following code to print all the lines which contains a specific word. And lets say you are searching for the word "foo".
import java.util.*;
import java.io.*;
public class Classname
{
public static void main(String args[])
{
File file =new File("file1.txt");
Scanner in = null;
try {
in = new Scanner(file);
while(in.hasNext())
{
String line=in.nextLine();
if(line.contains("foo"))
System.out.println(line);
}
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}}
Hope this code helps.
public static void grep(Reader inReader, String searchFor) throws IOException {
BufferedReader reader = null;
try {
reader = new BufferedReader(inReader);
String line;
while ((line = reader.readLine()) != null) {
if (line.contains(searchFor)) {
System.out.println(line);
}
}
} finally {
if (reader != null) {
reader.close();
}
}
}
Usage:
grep(new FileReader("file.txt"), "GrepMe");
Have a look at BufferedReader or Scanner for reading the file.
To check if a String contains a word use contains from the String-class.
If you show some effort I'm willing to help you out more.
you'll need to do something like this
public void readfile(){
try {
BufferedReader br;
String line;
InputStreamReader inputStreamReader = new InputStreamReader(new FileInputStream("file path"), "UTF-8");
br = new BufferedReader(inputStreamReader);
while ((line = br.readLine()) != null) {
if (line.contains("the thing I'm looking for")) {
//do something
}
//or do this
if(line.matches("some regular expression")){
//do something
}
}
// Done with the file
br.close();
br = null;
}
catch (Exception ex) {
ex.printStackTrace();
}
}