So I have this task to do, I need to expand text abbreviations from the message into their full form from the .csv file, I loaded that file into HashMap, with keys as abbreviations and values as full forms. There is a loop to iterate through the keys and if statement which replaces abbreviation to full form if it finds any. I kind of figured it out and it is working as it should but I want to send this changed String (with abbreviations expanded) somewhere else out of if statement to save the full message to the file. I know that this String exists only in this if statement but maybe there is another way of doing it? Or maybe I'm doing something wrong? I became a bit rusty with Java so maybe there is a simple explanation that I don't know about. Here is the code I have :
public class AbbreviationExpander {
static void AbrExpander(String messageBody) {
//read the .csv file
String csvFile = "textwords.csv";
String line = "";
String cvsSplitBy = ",";
String bodyOut = messageBody;
HashMap<String, String> list = new HashMap<>();
try (BufferedReader br = new BufferedReader(new FileReader(csvFile))) {
while ((line = br.readLine()) != null) {
String[] abbreviatonFile = line.split(cvsSplitBy);
//load the read data into the hashmap
list.put(abbreviatonFile[0], abbreviatonFile[1]);
}
for (String key : list.keySet()) {
//if any abbreviations found then replace them with expanded version
if (messageBody.contains(key)) {
bodyOut = bodyOut.replace(key, key + "<" + list.get(key).toLowerCase() + ">");
try {
File file = new File("SMS message" + System.currentTimeMillis() + ".txt");
FileWriter myWriter = new FileWriter(file);
myWriter.write(bodyOut);
myWriter.close();
} catch (IOException e) {
System.out.println("An error occurred.");
e.printStackTrace();
}
}
}
} catch (IOException f) {
f.printStackTrace();
}
}
}
Not sure I understood well your problem. But I think you should separate the different steps in your code.
I mean your try-catch block that writes your output should be outside the for-loop and outside the reading try-catch. And your for-loop should be outside your reading try-catch.
public class AbbreviationExpander {
static void AbrExpander(String messageBody) {
String csvFile = "textwords.csv";
String line = "";
String cvsSplitBy = ",";
String bodyOut = messageBody;
HashMap<String, String> list = new HashMap<>();
//read the .csv file
try (BufferedReader br = new BufferedReader(new FileReader(csvFile))) {
while ((line = br.readLine()) != null) {
String[] abbreviatonFile = line.split(cvsSplitBy);
//load the read data into the hashmap
list.put(abbreviatonFile[0], abbreviatonFile[1]);
}
} catch (IOException e) {
System.out.println("An error occurred.");
e.printStackTrace();
}
//if any abbreviations found then replace them with expanded version
for (String key : list.keySet()) {
if (messageBody.contains(key)) {
bodyOut = bodyOut.replace(key, key + "<" + list.get(key).toLowerCase() + ">");
}
}
//output the result in your file
try {
File file = new File("SMS message" + System.currentTimeMillis() + ".txt");
FileWriter myWriter = new FileWriter(file);
myWriter.write(bodyOut);
myWriter.close();
} catch (IOException e) {
System.out.println("An error occurred.");
e.printStackTrace();
}
}
}
I need to read from one text file(carsAndBikes.txt) and the write in either cars.txt or bikes.txt
carsAndBikes contains a list of cars and bikes and the first character of each name is C or B (C for Car and B for Bike). So far i have that but its showing cars and bikes content. Instead of the separated content.(CARS ONLY OR BIKES ONLY)
public static void separateCarsAndBikes(String filename) throws FileNotFoundException, IOException
{
//complete the body of this method to create two text files
//cars.txt will contain only cars
//bikes.txt will contain only bikes
File fr = new File("C:\\Users\\KM\\Documents\\NetBeansProjects\\Question4\\carsAndBikes.txt");
Scanner scanFile = new Scanner(fr);
String line;
while(scanFile.hasNextLine())
{
line = scanFile.nextLine();
if(line.startsWith("C"))
{
try(PrintWriter printWriter = new PrintWriter("C:\\Users\\KM\\Documents\\NetBeansProjects\\Question4\\cars.txt"))
{
printWriter.write(line);
}
catch(Exception e)
{
System.out.println("Message" + e);
}
}
else
{
try(PrintWriter printWriter = new PrintWriter("C:\\Users\\KM\\Documents\\NetBeansProjects\\Question4\\bikes.txt"))
{
printWriter.write(line);
}
catch(Exception e)
{
System.out.println("Message" + e);
}
}
}
//close the file
scanFile.close();
}
You're checking if the input filename starts with a c instead of checking if the line read starts with a c.
You should also open both your output files before your loop, and close them both after the loop.
// Open input file for reading
File file = new File("C:\\Users\\KM\\Documents\\NetBeansProjects\\Question4\\carsAndBikes.txt");
BufferedReader br = new BufferedReader(new FileReader(file)));
// Open bike outputfile for writing
// Open cars outputfile for writing
// loop over input file contents
String line;
while( line = br.readLine()) != null ) {
// check the start of line for the character
if (line.startsWith("C") {
// write to cars
} else {
// write to bikes
}
}
// close all files
i'm a beginner at java and still learning so please excuse my question if it sounds stupid.
i've been stuck on a straight forward problem i was given:
i'm supposed to read a text file and store the values of the text file in different variables. my text file looks like:
foo.txt
Directory_path=C:\University
school_name=SyracuseUni
i want to store the directory path and school_name in a new variable say
var_one = C:\University
and var_two = SyracuseUni
I was able to split it but in a single string.
public static void main(String[] args) throws IOException {
try {
BufferedReader br = new BufferedReader(new FileReader("C:\\foo.txt"));
String strLine = null;
String var_one = null;
String var_two = null;
while ((strLine = br.readLine()) != null) {
String[] parts = strLine.split("=");
String parameter = parts[1];
System.out.println(parameter);
}
}
catch (IOException e) {
e.printStackTrace();
}
}
this gives me an output like this which isn't how i want it:
C:\University
SyracuseUni
i will appreciate if anyone can guide me towards the right approach. thanks all.
There is already a simple way to deal with such files using java.util.Properties class. This could be an overkill if you are simply trying to learn how to read a file.
public static void main(String[] args) {
String myVar1 = null;
String myVar2 = null;
Properties prop = new Properties();
InputStream input = null;
try (FileInputStream input = new FileInputStream("pathToYourFile")) {
prop.load(input);
myVar1 = prop.getProperty("Directory_path");
myVar2 = prop.getProperty("school_name");
} catch (IOException ex) {
//Handle exception
}
}
Something simple would be using Java Properties. You could also store values in a map. If you really insisted on filling two separate varibles, you could always count how many lines you've went across in your while loop and use switch/case to determine which variable to fill.
public static void main(String[] args) throws IOException {
try {
BufferedReader br = new BufferedReader(new FileReader("C:\\foo.txt"));
String strLine = null;
HashMap<String, String> map = new HashMap<String, String>();
while ((strLine = br.readLine()) != null) {
String[] parts = strLine.split("=");
map.put(parts[0], parts[1]);
}
for (Entry<String, String> entry : map.entrySet()) {
String key = entry.getKey();
String value = entry.getValue();
System.out.println(key + " = " + value);
}
}
catch (IOException e) {
e.printStackTrace();
}
}
Forgive me if this is a basic (or not very well explained) question, I am fairly new to Java and have been reading extensive material as well as trying to understand the relevant Javadoc but to no avail.
To give a brief background as to what I am trying to create, I have created a reader class which reads data in from a csv file (4 lines long) including fields such as Item ID, price, description etc. I have created a separate demo class that displays the details of this csv file (through creating an instance of my reader class) and am now trying to create a method that asks the user to input an Item ID that then displays the corresponding Item, based on the ID input by the user. The part I am stuck on is accessing specific rows/columns in a csv file and then comparing these with a given string (entered by the user which corresponds to a specific field in the csv file)
This is what I have come up with thus far:
input = new Scanner(System.in);
System.out.println("Enter a product code");
String prodC = input.next();
//Here I want to know if there is a way of accessing a field in a csv file
Any ideas would be greatly appreciated.
UPDATE
Thank you for quick responses, am currently reading through and seeing how I can try to implement the various techniques. In response to the comment asking about the file reader, this is how I have set that out:
public CatalogueReader(String filename) throws FileNotFoundException {
this.filename = filename;
this.catalogue = new Catalogue();
Scanner csvFile;
try {
csvFile = new Scanner(new File(filename));
} catch (FileNotFoundException fnf) {
throw new FileNotFoundException("File has not been found!");
}
csvFile.useDelimiter("\n");
boolean first = true;
String productCode;
double price;
String description;
double weight;
int rating;
String category;
boolean ageRestriction;
String csvRows;
while (csvFile.hasNextLine()) {
csvRows = csvFile.nextLine();
if (first) {
first = false;
continue;
}
System.out.println(csvRows);
String[] fields = csvRows.split(",");
productCode = (fields[0].trim());
price = Double.parseDouble(fields[1].trim());
description = fields[2].trim();
weight = Double.parseDouble(fields[3].trim());
rating = Integer.parseInt(fields[4].trim());
category = fields[5].trim();
ageRestriction = Boolean.parseBoolean(fields[6].trim());
catalogue.addAProduct(new Item(productCode, price, description, weight, rating, category, ageRestriction));
}
csvFile.close();
}
}
ok so for a CSV file like this:
"1.0.0.0","1.0.0.255","16777216","16777471","AU","Australia"
"1.0.1.0","1.0.3.255","16777472","16778239","CN","China"
"1.0.4.0","1.0.7.255","16778240","16779263","AU","Australia"
"1.0.8.0","1.0.15.255","16779264","16781311","CN","China"
"1.0.16.0","1.0.31.255","16781312","16785407","JP","Japan"
"1.0.32.0","1.0.63.255","16785408","16793599","CN","China"
"1.0.64.0","1.0.127.255","16793600","16809983","JP","Japan"
"1.0.128.0","1.0.255.255","16809984","16842751","TH","Thailand"
here is a sample of how to read using Java Native Libraries
import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
public class CSVReader {
public static void main(String[] args) {
CSVReader obj = new CSVReader();
obj.run();
}
public void run() {
String csvFile = YOURFILEPATHHERE ;
BufferedReader br = null;
String line = "";
String cvsSplitBy = ",";
try {
br = new BufferedReader(new FileReader(csvFile));
while ((line = br.readLine()) != null) {
// use comma as separator
String[] country = line.split(cvsSplitBy);
System.out.println("Country [code= " + country[4]
+ " , name=" + country[5] + "]");
}
} 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");
}
}
does this help?
If you are just doing a single look-up and then exiting then just remember the String you are looking for. As you parse the lines compare to see if you have a match and if you do then return that line.
For repeated searches that would be very inefficient though. Assuming your data set is not too large for memory you would be better off parsing the file and putting it into a Map:
Map<String, Data> dataMap = new HashMap<>();
Parse the file, putting all the lines into the map
Then the lookup just becomes:
Data d = dataMap.get(lineKey);
If d is null then there is no matching line. If it not null then you have found your line.
You can create an array list of object. An object for each line in the CSV. Then search the array object with your search criteria.
User CSVReader framework to read the csv file. Sample code (not exactly what you want)
FileInputStream fis = new FileInputStream(file);
CSVReader reader = new CSVReader(new BufferedReader( new InputStreamReader(fis, "UTF-8" )));
ArrayList<String> row = new ArrayList<String>();
ArrayList<Entry> entries = new ArrayList<Entry>();
// a line = ID, Name, Price, Description
while (!reader.isEOF()) {
reader.readFields(row);
if( row.size() >= 4)
entries.add(new Entry(row.get(0), row.get(1), row.get(2), row.get(3)));
}
System.out.println("Size : "+entries);
Im coding a dictionary in java that the user inputs the words and they are stored in a .txt file in alphabetical order. When I use the SortWords method on its own it works fine, but when I combine it with the Option1Method which adds words to the dictionary it dosent work. Its like it changes the file type of the text file or something?? Any help would be greatly appreciated
public static void Option1Method() throws IOException {
FileWriter aFileWriter = new FileWriter("wordlist.txt", true);
PrintWriter out = new PrintWriter(aFileWriter);
String word = JOptionPane.showInputDialog(null, "Enter a word");
out.println(word);
out.close();
aFileWriter.close();
String inputFile = "wordlist.txt";
String outputFile = "wordlist.txt";
FileReader fileReader = new FileReader(inputFile);
BufferedReader bufferedReader = new BufferedReader(fileReader);
String inputLine;
List<String> lineList = new ArrayList<String>();
while ((inputLine = bufferedReader.readLine()) != null) {
lineList.add(inputLine);
}
fileReader.close();
Collections.sort(lineList);
FileWriter fileWriter = new FileWriter(outputFile);
PrintWriter out1 = new PrintWriter(fileWriter);
for (String outputLine : lineList) {
out.println(outputLine);
}
out1.flush();
out1.close();
fileWriter.close();
}
Ok Because I couldn't let this question go unanswered here is a simple example of how you might do this using some built in classes:
import java.io.*;
import java.util.*;
public class q15664563 {
public static void main(String[] args) throws IOException {
String wordlist = "wordlist.txt";
if(args.length == 1 && args[0].toLowerCase().charAt(0) == 'l') {
//List Words
SortedSet<String> dictionary = load(wordlist);
for(String word : dictionary) {
System.out.println(word);
}
} else if(args.length == 2 && args[0].toLowerCase().charAt(0) == 'a') {
//Add Word
SortedSet<String> dictionary = load(wordlist);
dictionary.add(args[1].toLowerCase());
save(dictionary, wordlist);
} else {
System.err.println("Correct usage:");
System.err.println(" q15664563 LIST --lists all words");
System.err.println(" q15664563 ADD [word] --adds word to list");
}
}
private static void save(SortedSet<String> dictionary, String wordlist) throws IOException {
FileWriter file = new FileWriter(wordlist);
BufferedWriter writer = new BufferedWriter(file);
for(String word : dictionary) {
writer.append(word);
writer.newLine();
}
writer.close();
file.close();
}
private static SortedSet<String> load(String wordlist) throws IOException {
SortedSet<String> dictionary = new TreeSet<String>();
FileReader file = new FileReader(wordlist);
BufferedReader reader = new BufferedReader(file);
String word;
while((word = reader.readLine()) != null) {
dictionary.add(word);
}
reader.close();
file.close();
return dictionary;
}
}
Some things to point out with this code, reading and writing are two separate operations so to keep things clean it helps to put them in their own functions (this is a matter of opinion of course). Also, as is so often the case there are data types that will help you, and TreeSet is a great example of one. It implements the SortedSet interface and is alphabetical every time you iterate through ti (actually it's alphabetical every time you insert into it, something to keep in mind as the set grows in length). Given this property if you wanted to optimize you may only need to use TreeSet when the list might change it's alphabetic order (on insert). When listing you would read the file line by line knowing that it was in the correct order. If you did this then you would no longer have a generic load() method that you could use in both instances (something to consider when trading simplicity of design for performance).