On this code I get an java.util.ConcurrentModificationException the method is in a webservice and first reads the file and checks if the vakNaam is in the file. Then it will be removed and the file will be rewritten. The exception is thrown by Exception2 (in the println)
#WebMethod
public boolean removeVak(String naam){
ArrayList<String> tempFile = new ArrayList<String>();
//Read the lines
boolean found = false;
BufferedReader br = null;
try {
br = new BufferedReader(new FileReader("C:/vak.txt"));
String strLine;
while ((strLine = br.readLine()) != null){
tempFile.add(strLine);
}
}catch(Exception e){
System.out.println("Exception " + e);
}finally {
try {
if (br != null)
br.close();
} catch (Exception ex) {
ex.printStackTrace();
}
}
//Write the lines
BufferedWriter out= null;
try{
for(String s : tempFile){
String [] splitted = s.split(" ");
if(splitted[0].equals(naam)){
tempFile.remove(s);
found = true;
}
}
out = new BufferedWriter(new FileWriter("C:/vak.txt", false));
for(String s: tempFile){
out.newLine();
out.write(s);
}
out.close();
} catch (Exception e) {
System.out.println("Exception2 " + e);
return false;
}finally {
try {
if (out != null)
out.close();
} catch (Exception ex) {
ex.printStackTrace();
}
}
return found;
}
The error is in this part:
for (String s : tempFile){
String [] splitted = s.split(" ");
if (splitted[0].equals(naam)){
tempFile.remove(s);
found = true;
}
}
Don't modify the list you are iterating over. You could solve this by using the Iterator explicitely:
for (Iterator<String> it = tempFile.iterator(); it.hasNext();) {
String s = it.next();
String [] splitted = s.split(" ");
if (splitted[0].equals(naam)){
it.remove();
found = true;
}
}
The Java 5 enhanced for loop uses an Iterator underneath. So When you remove from tempFile the fail fast nature kicks in and throws the Concurrent exception. Use an iterator and call its remove method, which will remove from the underlying Collection.
Related
I'm reading from a text file which looks like this:
1
The Adventures of Tom Sawyer
2
Huckleberry Finn
4
The Sword in the Stone
6
Stuart Little
I have to make it so that the user can enter the reference number and the program will perform binary and linear search and output the title. My teacher said to use two ArrayLists, one for the numbers and one for the titles, and output from them. I just can't figure out how to skip lines so I can add to the corresponding arraylist.
int number = Integer.parseInt(txtInputNumber.getText());
ArrayList <String> books = new ArrayList <>();
ArrayList <Integer> numbers = new ArrayList <> ();
BufferedReader br = null;
try {
br = new BufferedReader(new FileReader("bookList.txt"));
String word;
while ((word = br.readLine()) != null ){
books.add(word);
}
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
br.close();
} catch (IOException ex) {
ex.printStackTrace();
}
}
Thanks in advance, I appreciate any help!
You can check if you are in even or odd lines by doing a modulo 2 operation on the line number:
try (BufferedReader br = new BufferedReader(new FileReader("bookList.txt"))) {
String word;
int lineCount = 0;
while ((word = br.readLine()) != null ){
if (++lineCount % 2 == 0) {
numbers.add(Integer.parseInt(word));
} else {
books.add(word);
}
}
} catch (IOException e) {
e.printStackTrace();
}
int number = Integer.parseInt(txtInputNumber.getText());
ArrayList <String> books = new ArrayList <>();
ArrayList <Integer> numbers = new ArrayList <> ();
BufferedReader br = null;
try {
br = new BufferedReader(new FileReader("bookList.txt"));
String word;
while ((word = br.readLine()) != null ){
numbers.add(Integer.valueOf(word));
word = br.readLine()
books.add(word);
}
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
br.close();
} catch (IOException ex) {
ex.printStackTrace();
}
}
You could make check to see if it is actually a integer, that you read from the file. As far as I remember, there is no built in method to do this, but you can define your own as:
boolean tryParseInt(String value) {
try {
Integer.parseInt(value);
return true;
} catch (NumberFormatException e) {
return false;
}
}
Then just make a check to see if the line you have read in is a integer or not.
int number = Integer.parseInt(txtInputNumber.getText());
ArrayList <String> books = new ArrayList <>();
ArrayList <Integer> numbers = new ArrayList <> ();
BufferedReader br = null;
try {
br = new BufferedReader(new FileReader("bookList.txt"));
String word;
while ((word = br.readLine()) != null ){
if (tryParseInt(word))
numbers.add(Integer.parseInt(word))
else
books.add(word);
}
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
br.close();
} catch (IOException ex) {
ex.printStackTrace();
}
}
Hope this help!
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();
}
}
}
Am reading data from csv file , i have test for which this data will be the input .
i want it to run as tescase for every set of value. for that am using data provider
The problem is , it is taking only the last set row of data , please help me in debugging the code
For eg : if my csv has following data
name1 id1 text1
name2 id2 text2
name3 id3 text3
it taking only last row name3 id3 text3 and running the test only once not three times.
#DataProvider(name = "test")
public Object[][] provider( ) throws InterruptedException
{
Object[][] returnObject ;
String[] checkpoint = ReadfromCSV();
count = count + 1;
returnObject = new Object[][]{checkpoint };
return returnObject;
}
#Test(description = "Test", groups = "test" , dataProvider = "test")
public void compare(String val1,String val2,String val3,String val4,String val5,String val6,String val7,String val8,String val9,String val10,String val11 ) {
System.out.println("1:" + val1);
System.out.println("4:" + val2);
System.out.println("5:" + val3);
}
#SuppressWarnings("null")
public String[] ReadfromCSV() throws InterruptedException {
String[] data= null;
String csvFile = "F:/sample1.csv";
BufferedReader br = null;
String line = "";
String cvsSplitBy = ",";
try {
br = new BufferedReader(new FileReader(csvFile));
while ((line = br.readLine()) != null) {
// use comma as separator
data= line.split(cvsSplitBy);
}
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
if (br != null) {
try {
br.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
System.out.println("Done");
return data;
}
You should read entire file in data provider and return iterator of test cases. Here is some pseudocode for data provider. Notice that I used List<String []> to store test cases instead of Object[][]. This allows you do define test cases dynamically.
#DataProvider(name = "test")
public Iterator<Object []> provider( ) throws InterruptedException
{
List<Object []> testCases = new ArrayList<>();
String[] data= null;
//this loop is pseudo code
br = new BufferedReader(new FileReader(csvFile));
while ((line = br.readLine()) != null) {
// use comma as separator
data= line.split(cvsSplitBy);
testCases.add(data);
}
return testCases.iterator();
}
public String[][] ReadfromCSV() throws InterruptedException {
int count =0;
String[] data= null;
String returnObj[][] = null;
//System.out.println(System.getProperty("user.dir"));
String csvFile = System.getProperty("user.dir")+ "/src/test/resources/testdata.csv";
BufferedReader br = null;
String line = "";
String cvsSplitBy = ",";
ArrayList<String> content = new ArrayList<String>();
try {
//this loop is pseudo code
br = new BufferedReader(new FileReader(csvFile));
int datalength = 0;
int listsize =0;;
while ((line = br.readLine()) != null) {
// use comma as separator
content.add(line);
}
System.out.println(content);
listsize = content.size();
datalength = content.get(0).split(cvsSplitBy).length;
returnObj = new String[listsize][datalength];
for (int i = 0; i<listsize; i++) {
data = content.get(i).split(cvsSplitBy);
for (int j=0; j< datalength ; j++) {
returnObj[i][j] = data[j];
}
}
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
if (br != null) {
try {
br.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
System.out.println("Done");
return returnObj;
}}
I have a large text file with phrases such as:
citybred JJ
Brestowe NNP
STARS NNP NNS
negative JJ NN
investors NNS NNPS
mountain NN
My objective is to keep the first word of each line, without the spaces, and also make them lowercase.
EX:
citybred
brestowe
stars
negative
investors
mountain
Would be returned if the above text was evaluated.
Any help?
Current code:
public class FileLinkList
{
public static void main(String args[])throws IOException{
String content = new String();
File file = new File("abc.txt");
LinkedList<String> list = new LinkedList<String>();
try {
Scanner sc = new Scanner(new FileInputStream(file));
while (sc.hasNextLine()){
content = sc.nextLine();
list.add(content);
}
sc.close();
} catch(FileNotFoundException fnf){
fnf.printStackTrace();
} catch (Exception e) {
e.printStackTrace();
System.out.println("\nProgram terminated Safely...");
}
Collections.reverse(list);
Iterator i = list.iterator();
while (i.hasNext()) {
System.out.print("Node " + (count++) + " : ");
System.out.println(i.next());
}
}
}
If your token and its POS tag is separated by space :
public class FileLinkList{
public static void main(String[] args) {
BufferedReader br = null;
LinkedList<String> list = new LinkedList<String>();
String word;
try {
String sCurrentLine;
br = new BufferedReader(new FileReader("LEXICON.txt"));
while ((sCurrentLine = br.readLine()) != null) {
System.out.println(sCurrentLine);
word = sCurrentLine.trim().split(" ")[0];
list.add(word.toLowerCase());
}
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
if (br != null)
br.close();
} catch (IOException ex) {
ex.printStackTrace();
}
}
}
}
Add the following:
content = sc.nextLine();
string[] tokens = content.split(new char[] {' '}, StringSplitOptions.RemovEemptyEntries);
// You can add some validations here...
string word = tokens[0].ToLowerCase();
Try this :
public class FileLinkList {
public static void main(String args[])throws IOException{
String content = new String();
int count=1;
File file = new File("abc.txt");
LinkedList<String> list = new LinkedList<String>();
try {
Scanner sc = new Scanner(new FileInputStream(file));
while (sc.hasNextLine()){
content = sc.nextLine();
if (content != null && content.length() > 0)) {
list.add(content.trim().split(" ")[0].toLowerCase());
}
}
sc.close();
} catch(FileNotFoundException fnf){
fnf.printStackTrace();
} catch (Exception e) {
e.printStackTrace();
System.out.println("\nProgram terminated Safely...");
}
for (String listItem : list) {
System.out.println(listItem);
}
}
}
With Apache Commons IO it is much simpler to read a file into a list of Strings.
import org.apache.commons.io.FileUtils;
List<String> lines = FileUtils.readLines(new File("abc.txt"));
List<String firstWords = new ArrayList<>();
for (String line : lines) {
String firstWord = line.split(" ")[0].toLowerCase();
firstWords.add(firstWord);
}
I have a program I wrote that can read a csv file. The csv file have two columns one for clusters number and the other is for users. what I need for the program is not to repeat the user. Instead, to write the user once and in each cluster to simply write 1 if the user had shown in that cluster number.
package parsing;
public static void main(String[]args){
String fileName= "ClusterResult(final1).csv";//reading the file
File file = new File(fileName);
try {
Scanner inputStream = new Scanner(file);
while (inputStream.hasNext()){
String data = inputStream.next();
String [] myArray= data.split(",");
for(int i =0; i<=27;i++){// because I have 27 clusters
Arrays.sort(myArray);
int founditem= Arrays.binarySearch(myArray, String.valueOf(i));
if (founditem>-1 )
System.out.print("1"); //if the user name showed in the cluster the user should have one next to the cluster number
else
System.out.print("0");
}
System.out.println();
System.out.println(myArray[1] );
}
inputStream.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
}
}
the output of the program is :
1000000000000000000000000000
ElDaddy
1000000000000000000000000000
Lxve
1000000000000000000000000000
Lxve
0000001000000000000000000000
ElDaddy
where it should be for example :
1000001000011000010100000000
ElDaddy
You say in your question your csv has two columns, if that's true, try something like this:
public static void main(String[] args) {
HashMap<String, HashSet<String>> map = new HashMap<String, HashSet<String>>();
String fileName = "ClusterResult(final1).csv";// reading the file
FileReader file = null;
try {
file = new FileReader(new File(fileName));
} catch (FileNotFoundException e1) {
System.err.println("File " + fileName + " not found!");
e1.printStackTrace();
}
BufferedReader br = new BufferedReader(file);
String line;
try {
while ((line = br.readLine()) != null) {
String[] data = line.split(",");
generateClusters(data[0], data[1], map);
}
for (Entry<String, HashSet<String>> entry : map.entrySet()) {
for (int i = 0; i < 27; i++) {
if (entry.getValue().contains(String.valueOf(i)))
System.out.print(1);
else
System.out.print(0);
}
System.out.println();
System.out.println(entry.getKey());
}
} catch (IOException e) {
System.err.println("Error when reading");
e.printStackTrace();
} finally {
if (br != null) {
try {
br.close();
} catch (IOException e) {
System.err.println("Unexpected error");
e.printStackTrace();
}
}
}
}
public static void generateClusters(String e1, String e2,
HashMap<String, HashSet<String>> map) {
HashSet<String> clustersOfUser = map.get(e1);
if (clustersOfUser == null) {
clustersOfUser = new HashSet<String>();
map.put(e1,clustersOfUser);
}
clustersOfUser.add(e2);
}
What we are doing here is grouping the users in a HashMap, but storing the clusters
as keys.