I'm trying to search a certain string from an input file. Firstly, the code stores data from input file and then it searches the user input data in the text file, but when i try to print one of the variables it ends up being null.
public class Test {
public static void main(String args[])throws IOException, FileNotFoundException {
BufferedReader input = null;
PrintWriter output = null;
try {
input = new BufferedReader (new FileReader ("kolej.txt"));
Scanner in = new Scanner(System.in);
in.useDelimiter("\n");
int index = 0;
String indata = null;
System.out.println("UITM College and Non-Residents Registration System");
System.out.println("Enter your student id: ");
String matrix = in.next();
UITM student[] = new UITM[10];
//storing data into array
while ((indata = input.readLine())!= null) {
StringTokenizer st = new StringTokenizer(indata,";");
student[index] = new Kolej(st.nextToken(), st.nextToken(), st.nextToken(), Integer.parseInt(st.nextToken()), st.nextToken(),Integer.parseInt(st.nextToken()), st.nextToken(),Integer.parseInt(st.nextToken())) ;
index++;
}
//searching
Scanner txtscan = new Scanner(new File("kolej.txt"));
while(txtscan.hasNextLine()) {
matrix = txtscan.nextLine();
if(matrix.indexOf("word") != -1) {
System.out.println(student[0].getName());
}
}
input.close();
output.close();
}
catch (FileNotFoundException fnfe) {
System.out.println("File not found");
}
catch (IOException ioe) {
System.out.println(ioe.getMessage());
}
catch (Exception e) {
System.out.println(e.getMessage());
}
}
}
Related
Create a file called Display.java
Write a try-catch statement that attemps to create a Scanner object to read from the logfile ('logfile.txt').
If the file does not exist, catch the FileNotFoundException, print "Cannot find logfile!" then "Exiting..." and quit the program.
If the file exists, prompt the user to enter start and end indices
Print out all the lines between the start and end line numbers (inclusive).
public class CopyOfDIsplay {
public static void main(String[] args) throws IOException {
File file = new File("C:\\Users\\vutom\\IdeaProjects\\COS101 TERM4 ASSIGNMENT\\src\\logfile.txt");
FileInputStream fileInputStream = new FileInputStream(file);
InputStreamReader inputStreamReader = new InputStreamReader(fileInputStream);
BufferedReader bufferedReader = new BufferedReader(inputStreamReader);
String line = bufferedReader.readLine();
String[] Numberz = line.split(":");
Scanner s = new Scanner(System.in);
System.out.println("Enter two numbers , a start and end index separated by a space:");
String Inputs = s.nextLine();
String[] numbers = Inputs.split("\s");
String rangeMin = numbers[0];
String rangeMax = numbers[1];
int start = Integer.parseInt(rangeMin);
int end = Integer.parseInt(rangeMax);
try {
while (line != null) {
for (String num :Numberz) {
if (line.codePointAt(start) >= && line.codePointAt(end) <= end) {
System.out.println(line);
}
else {
System.out.println(line);
}
}
}
bufferedReader.close();
} catch (FileNotFoundException e) {
System.out.println("Cannot find logfile");
} catch (IOException ex) {
throw new RuntimeException(ex);
}
System.out.println("Exiting. . . ");
}
}
How can I open a .txt file and read numbers separated by enters or spaces into an array list?
Read file, parse each line into an integer and store into a list:
List<Integer> list = new ArrayList<Integer>();
File file = new File("file.txt");
BufferedReader reader = null;
try {
reader = new BufferedReader(new FileReader(file));
String text = null;
while ((text = reader.readLine()) != null) {
list.add(Integer.parseInt(text));
}
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
if (reader != null) {
reader.close();
}
} catch (IOException e) {
}
}
//print out the list
System.out.println(list);
A much shorter alternative is below:
Path filePath = Paths.get("file.txt");
Scanner scanner = new Scanner(filePath);
List<Integer> integers = new ArrayList<>();
while (scanner.hasNext()) {
if (scanner.hasNextInt()) {
integers.add(scanner.nextInt());
} else {
scanner.next();
}
}
A Scanner breaks its input into tokens using a delimiter pattern, which by default matches whitespace. Although default delimiter is whitespace, it successfully found all integers separated by new line character.
Good news in Java 8 we can do it in one line:
List<Integer> ints = Files.lines(Paths.get(fileName))
.map(Integer::parseInt)
.collect(Collectors.toList());
try{
BufferedReader br = new BufferedReader(new FileReader("textfile.txt"));
String strLine;
//Read File Line By Line
while ((strLine = br.readLine()) != null) {
// Print the content on the console
System.out.println (strLine);
}
//Close the input stream
in.close();
}catch (Exception e){//Catch exception if any
System.err.println("Error: " + e.getMessage());
}finally{
in.close();
}
This will read line by line,
If your no. are saperated by newline char. then in place of
System.out.println (strLine);
You can have
try{
int i = Integer.parseInt(strLine);
}catch(NumberFormatException npe){
//do something
}
If it is separated by spaces then
try{
String noInStringArr[] = strLine.split(" ");
//then you can parse it to Int as above
}catch(NumberFormatException npe){
//do something
}
File file = new File("file.txt");
Scanner scanner = new Scanner(file);
List<Integer> integers = new ArrayList<>();
while (scanner.hasNext()) {
if (scanner.hasNextInt()) {
integers.add(scanner.nextInt());
}
else {
scanner.next();
}
}
System.out.println(integers);
import java.io.*;
public class DataStreamExample {
public static void main(String args[]){
try{
FileWriter fin=new FileWriter("testout.txt");
BufferedWriter d = new BufferedWriter(fin);
int a[] = new int[3];
a[0]=1;
a[1]=22;
a[2]=3;
String s="";
for(int i=0;i<3;i++)
{
s=Integer.toString(a[i]);
d.write(s);
d.newLine();
}
System.out.println("Success");
d.close();
fin.close();
FileReader in=new FileReader("testout.txt");
BufferedReader br=new BufferedReader(in);
String i="";
int sum=0;
while ((i=br.readLine())!= null)
{
sum += Integer.parseInt(i);
}
System.out.println(sum);
}catch(Exception e){System.out.println(e);}
}
}
OUTPUT::
Success
26
Also, I used array to make it simple.... you can directly take integer input and convert it into string and send it to file.
input-convert-Write-Process... its that simple.
Whatever I did, I did not write a new data on a new line in the file.
How can I fix it?
For example mary's score is 100 and smith's score is 150, but in the txt file it is
mary 100smith 150
I wanna smith 150 in a new line
public class HighScores {
public HighScores(){
String txt = "";
Scanner sc = null;
PrintWriter pw = null;
File Checker = null;
try{
Checker = new File("highScores.txt");
if(!Checker.exists()){
Checker.createNewFile();
}
sc = new Scanner(new File("highScores.txt"));
while(sc.hasNextLine()){
txt = txt.concat(sc.nextLine()+"\n");
}
String score=String.valueOf(Game3.score);
String name = NewPlayer.name;
txt = txt.concat(name + " "+ score +"\n");
pw = new PrintWriter(Checker);// writing the checker
pw.write(txt +"\r\n");
pw.println() gives the same problem too.
}catch(FileNotFoundException fnfe){
fnfe.printStackTrace();
}catch(IOException ioe){
ioe.printStackTrace();
}finally{
sc.close();
pw.close();
}
}
}
The code is dodgy, but should actually do what you expect of it.
You are probably viewing the resulting file with a Windows notepad app. It expects "\r\n" as a newline separator, as do most other Windows apps.
Use the following code
public class HighScores {
public HighScores() {
String txt = "";
Scanner sc = null;
PrintWriter pw = null;
File Checker = null;
try {
Checker = new File("highScores.txt");
if (!Checker.exists()) {
Checker.createNewFile();
}
sc = new Scanner(new File("highScores.txt"));
while (sc.hasNextLine()) {
txt = txt.concat(sc.nextLine() + "\n");
}
String score = String.valueOf(Game3.score);
String name = NewPlayer.name;
txt = txt + name + " " + score;
pw = new PrintWriter(Checker);// writing the checker
pw.println(txt);
} catch (FileNotFoundException fnfe) {
fnfe.printStackTrace();
} catch (IOException ioe) {
ioe.printStackTrace();
} finally {
sc.close();
pw.close();
}
}
}
ive gotten this far, but this doesnt work to read in the file, thats the part im stuck on. i know that you need to use the scanner, but im not sure what im missing here. i think it needs a path to the file also, but i dont know where to put that in
public class string
{
public static String getInput(Scanner in) throws IOException
{
{
Scanner keyboard = new Scanner(System.in);
System.out.println("Enter file");
String filename =keyboard.next();
File inputFile = new File(filename);
Scanner input = new Scanner(inputFile);
String line;
while (input.hasNext())
{
line= input.nextLine();
System.out.println(line);
}
input.close();
}
if(filename.isEmpty())
{
System.out.println("Sorry, there has been an error. You must enter a string! (A string is some characters put together.) Try Again Below.");
return getInput(in);
}
else
{
return filename;
}
}
public static int getWordCount(String input)
{
String[] result = input.split(" ");
return result.length;
}
public static void main(String[] args)
{
DecimalFormat formatter = new DecimalFormat("0.##");
String input = getInput(new Scanner(System.in));
float counter = getWordCount(input);
System.out.println("The number of words in this string ("+input+") are: " + counter);
Scanner keyboard= new Scanner(System.in);
}
}
//end of code
First of all, when doing file I/O in Java, you should properly handle all exceptions and errors that can occur.
In general, you need to open streams and resources in a try block, catch all exceptions that happen in a catch block and then close all resources in a finally block. You should read up more on these here as well.
For using a Scanner object, this would look something like:
String token = null;
File file = null;
Scanner in = null;
try {
file = new File("/path/to/file.txt");
in = new Scanner(file);
while(in.hasNext()) {
token = in.next();
// ...
}
} catch (FileNotFoundException e) {
// if File with that pathname doesn't exist
e.printStackTrace();
} finally {
if(in != null) { // pay attention to NullPointerException possibility here
in.close();
}
}
You can also use a BufferedReader to read a file line by line.
BufferedReader reader = new BufferedReader(new FileReader("/path/to/file.txt"));
String line = null;
while ((line = reader.readLine()) != null) {
// ...
}
With added exception handling:
String line = null;
FileReader fReader = null;
BufferedReader bReader = null;
try {
fReader = new FileReader("/path/to/file.txt");
bReader = new BufferedReader(fReader);
while ((line = bReader.readLine()) != null) {
// ...
}
} catch (FileNotFoundException e) {
// Missing file for the FileReader
e.printStackTrace();
} catch (IOException e) {
// I/O Exception for the BufferedReader
e.printStackTrace();
} finally {
if(fReader != null) { // pay attention to NullPointerException possibility here
try {
fReader.close();
} catch (IOException e) {
e.printStackTrace();
}
}
if(bReader != null) { // pay attention to NullPointerException possibility here
try {
bReader.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
In general, use the Scanner for parsing a file, and use the BufferedReader for reading the file line by line.
There are other more advanced ways to perform reading/writing operations in Java. Check out some of them here
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);
}