I'm doing an assignment for school (so I can unfortunately not use third party libraries) and the goal is to read a csv file into an array, process it in a different method, and print it in another. This is what I have so far but I get the error:
Type mismatch: cannot convert from List<String> to Collection<? extends String[]>.
Here is my code:
package client.java;
import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
public abstract class Client{
String file = "bank-Detail.csv";
ArrayList<String[]> bank = new ArrayList<>();
public Client(String file) {
this.file = file;
}
public void readData() throws IOException {
int count = 0;
String file = "bank-Detail.txt";
try {
BufferedReader br = new BufferedReader(new FileReader(file));
String line = "";
while ((line = br.readLine()) != null) {
bank.addAll(Arrays.asList(line.split(",")));
The line (Arrays.asList(line.split(","))); is where I get the error.
String[] entries = line.split(",");
String[][] numbers = (String[][]) bank.toArray(new String[bank.size()][12]);
}
} catch (FileNotFoundException e) {
}
}
public void processData() {
}
public void printData() {
}
ArrayList<String[]> bank is a list of arrays, so instead of doing
bank.addAll(Arrays.asList(line.split(",")));
you just need to do
bank.add(line.split(","));
Here's javadoc for split method, it returns an array of String which is what we need to add into the list.
Each entry of your list bank is an arrray of String. But
But at this line
bank.addAll(Arrays.asList(line.split(",")));
You are trying to add a list of string List<String> to bank using addAll. But if you want to use addAll you have to add List<String []>.
There is a small fix to your problem:
bank.add(line.split(","))
As line.split(",") will return an array of String.
And you are good to go.
Related
I'm a little confused as to how best to implement a simple DataProvider, having not done so before.
I have a very simple comma delimited .csv file:
978KAL,625JBH,876SSH,452GSH
I simply need to read it in and iterate over the records, running the same test for each record until done.
My code so far:
String csvFile = "src/test/resources/registrationsData.csv";
BufferedReader br = null;
String line = "";
String cvsSplitBy = ",";
#DataProvider(name="getRegistrations")
private Object[] getCSVTestData() {
Object [] registrationsObject;
try {
br = new BufferedReader(new FileReader(csvFile));
while ((line = br.readLine()) != null) {
// use comma as separator
String [] registrations = line.split(cvsSplitBy);
System.out.println( registrations[0] + "," + registrations[1]);
}
} catch//File not found & IOException handling here
registrationsObject = new Object[][]{registrations};
return registrationsObject;
}
#Test(dataProvider = "getRegistrations")
public void getRegistrations(String registration){
Object[] objRegArray = getCSVTestData();
for(int i=0; objRegArray.length>i; i++){
//run tests for every record in the array (csv file)
}
}
I know that I need to use an Object array return type for the Data Provider method.
I'm unclear as to how (and/or the best way) to retrieve each record from the objRegArray object.
This is a basic Collections question I guess; can anyone point me the right way?
Check this code with my explanation below:
package click.webelement.testng;
import org.testng.annotations.DataProvider;
import org.testng.annotations.Test;
import java.io.File;
import java.io.FileNotFoundException;
import java.util.Iterator;
import java.util.Scanner;
public class OneLineCSV {
final static String CSV_FILE = "/path_to_file/oneline.csv";
final static String DELIMETER = ",";
#DataProvider(name = "test")
public Iterator<Object[]> testDP(){
try {
Scanner scanner = new Scanner(new File(CSV_FILE)).useDelimiter(DELIMETER);
return new Iterator<Object[]>() {
#Override
public boolean hasNext() {
return scanner.hasNext();
}
#Override
public Object[] next() {
return new Object[]{scanner.next()};
}
};
} catch (FileNotFoundException e) {
e.printStackTrace();
return null;
}
}
#Test(dataProvider = "test")
public void testOneLineCSV(String value){
System.out.println(value);
}
}
So I would use Scanner class hence it has the convenient facility to parse a string into tokens.
I would also use the capability to return Iterator<Object[]> in your data provider since Scanner is designed in that way. You simply wrap it with new Iterator that converts String that is returned by Scanner.next() to new Object[]{scanner.next}.
Using Iterator with Scanner is really more comfortable since you may not know how many values you will have to provide. So you shouldn't care of defining array size.
I'm a java beginner and I'm doing a small project about dictionary, now I want to save word and translate mean in file, because my native language often have space like chicken will be con gà so, I must use other way, not by space, but I really don't know how to do that, a word and it translation in one line, separate by "tab", mean multi space like chicken con gà now I want to get 2 words and store it in my array of Words which I created before, so I want to do something like
w1=word1inline;
w2=word2inline;
Word(word1inline,word2inline);(this is a member of array);
please help me, thanks a lot, I just know how to read line from file text, and use split to get word but I am not sure how to read by multi space.
import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.util.ArrayList;
public class docfile {
public static void main(String[] args)
{
String readLine;
ArrayList<String>str=new ArrayList<>(String);
try {
File file = new File("text.txt");
BufferedReader b = new BufferedReader(new FileReader(file));
while ((readLine = b.readLine()) != null) {
str.add()=readLine.split(" ");
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
If you stick to using tabs as a separator, this should work:
package Application;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.util.ArrayList;
public class Application {
public static void main(String[] args) {
String line;
ArrayList<String> str = new ArrayList<>();
try {
File file = new File("text.txt");
BufferedReader b = new BufferedReader(new FileReader(file));
while ((line = b.readLine()) != null) {
for (String s : line.split("\t")) {
str.add(s);
}
}
str.forEach(System.out::println);
} catch (IOException e) {
e.printStackTrace();
}
}
}
Why not just use a properties file?
dict.properties:
chicken=con gá
Dict.java:
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.Properties;
public class Dict {
public static void main(String[] args) throws IOException {
Properties dict = new Properties();
dict.load(Files.newBufferedReader(Paths.get("dict.properties")));
System.out.println(dict.getProperty("chicken"));
}
}
Output:
con gá
If your line is like this chicken con gà you can use indexof() method to find the first space in the string.
Then you can substring each word by using substring() method.
readLine = b.readLine();
ArrayList<String>str=new ArrayList<>();
int i = readLine.indexOf(' ');
String firstWord = readLine.substring(0, i);
String secondWord = readLine.substring(i+1, readLine.length());
str.add(firstWord);
str.add(secondWord);
I'm trying to use HAshmap in a class in order to, from other classes, look up product descriptions given the product code.
Whith the setter (populate) everything seems to work fine , but when I'm tryig to use a getter (getdesc) i get an error.
The csv file i'm using has only 2 filds (cod,des). Later, I plan to populate the hashmap from JDBC SQL server source.
I'm probabbly using the wrong syntax. I'll apreciate if anyone can help.
That's my current class code:
package bookRecommender;
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.text.ParseException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Map;
import java.util.StringTokenizer;
public class ProdutoDescricao
{
public static void main(String[] args) {}
#SuppressWarnings({ "resource", "unused" })
public static void populate(String[] args) throws IOException {
Map<String, ArrayList<String>> produtos=null;
try {
String csvFile = "Data/produto_descricao.csv";
BufferedReader br = new BufferedReader(new FileReader(csvFile));
String line = "";
StringTokenizer st = null;
produtos= new HashMap<String, ArrayList<String>>();
int lineNumber = 0;
int tokenNumber = 0;
while ((line = br.readLine()) != null) {
lineNumber++;
st = new StringTokenizer(line, ",");
while (st.hasMoreTokens()) {
tokenNumber++;
String token_lhs=st.nextToken();
String token_rhs= st.nextToken();
ArrayList<String> arrVal = produtos.get(token_lhs);
if (arrVal == null) {
arrVal = new ArrayList<String>();
produtos.put(token_lhs,arrVal);
}
arrVal.add(token_rhs);
}
}
System.out.println("Final Hashmap is : "+produtos);
} catch (Exception e) {
System.err.println("CSV file cannot be read : " + e);
}
}
public String getdesc (long cod)
{
return produto.get(cod);
//Here is the sysntax error
}
}
produtos= new HashMap<String, ArrayList<String>>() produtos it has no values it is blank.
ArrayList<String> arrVal = produtos.get(token_lhs); this line has issue, you have to first add values in your map then get those values.
You have a map with String key and ArrayList values types, but you trying to retrieve value with long key and String values type.
public ArrayList<String> getdesc (String cod)
{
return produtos.get(cod);
}
Also declare field 'produtos':
private static Map<String, ArrayList<String>> produtos;
Full class code: http://pastebin.com/QLZryqT8
I have to read data from text.txt file, but I have strange error, my output is: [Ljava.lang.String;#5f0a94c5.
The contents of text.txt file:
test::test.1::test.2
test2::test2.1::test2.2
test3::test3.1::test3.2
The code:
import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Arrays;
public class test {
public static void main(String[] args){
ArrayList<String> data = new ArrayList<String>();
try (BufferedReader br = new BufferedReader(new FileReader("test.txt"))) {
String CurrLine;
while((CurrLine = br.readLine()) != null) {
data.add(CurrLine);
}
String[] dataArray = new String[data.size()];
data.toArray(dataArray);
Arrays.toString(dataArray);
System.out.println(dataArray);
} catch(FileNotFoundException ex) {
System.out.println("FNFE");
} catch(IOException ex) {
System.out.println("IOE");
}
}
}
You need to use:
System.out.println(Arrays.toString(dataArray));
In your code, Arrays.toString(dataArray); does nothing as you don't do anything with its returned value.
BTW, as #ZouZou pointed out, you can also print your ArrayList directly:
System.out.println(data);
Your code : System.out.println(dataArray); will output the hashcode value for the object dataArray. Any array in Java does not override equals() method. As a result, when you try to print the value of the array object, java.lang.Object.equals() method is invoked which prints the hashcode of the object .
Instead try using System.out.println(Arrays.toString(dataArray));
I was wondering if anyone has logic in java that removes duplicate lines while maintaining the lines order.
I would prefer no regex solution.
public class UniqueLineReader extends BufferedReader {
Set<String> lines = new HashSet<String>();
public UniqueLineReader(Reader arg0) {
super(arg0);
}
#Override
public String readLine() throws IOException {
String uniqueLine;
if (lines.add(uniqueLine = super.readLine()))
return uniqueLine;
return "";
}
//for testing..
public static void main(String args[]) {
try {
// Open the file that is the first
// command line parameter
FileInputStream fstream = new FileInputStream(
"test.txt");
UniqueLineReader br = new UniqueLineReader(new InputStreamReader(fstream));
String strLine;
// Read File Line By Line
while ((strLine = br.readLine()) != null) {
// Print the content on the console
if (strLine != "")
System.out.println(strLine);
}
// Close the input stream
in.close();
} catch (Exception e) {// Catch exception if any
System.err.println("Error: " + e.getMessage());
}
}
}
Modified Version:
public class UniqueLineReader extends BufferedReader {
Set<String> lines = new HashSet<String>();
public UniqueLineReader(Reader arg0) {
super(arg0);
}
#Override
public String readLine() throws IOException {
String uniqueLine;
while (lines.add(uniqueLine = super.readLine()) == false); //read until encountering a unique line
return uniqueLine;
}
public static void main(String args[]) {
try {
// Open the file that is the first
// command line parameter
FileInputStream fstream = new FileInputStream(
"/home/emil/Desktop/ff.txt");
UniqueLineReader br = new UniqueLineReader(new InputStreamReader(fstream));
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());
}
}
}
If you feed the lines into a LinkedHashSet, it ignores the repeated ones, since it's a set, but preserves the order, since it's linked. If you just want to know whether you've seena given line before, feed them into a simple Set as you go on, and ignore those which the Set already contains/contained.
It can be easy to remove duplicate line from text or File using new java Stream API. Stream support different aggregate feature like sort,distinct and work with different java's existing data structures and their methods. Following example can use to remove duplicate or sort the content in File using Stream API
package removeword;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.OpenOption;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.Arrays;
import java.util.Scanner;
import java.util.stream.Stream;
import static java.nio.file.StandardOpenOption.*;
import static java.util.stream.Collectors.joining;
public class Java8UniqueWords {
public static void main(String[] args) throws IOException {
Path sourcePath = Paths.get("C:/Users/source.txt");
Path changedPath = Paths.get("C:/Users/removedDouplicate_file.txt");
try (final Stream<String> lines = Files.lines(sourcePath )
// .map(line -> line.toLowerCase()) /*optional to use existing string methods*/
.distinct()
// .sorted()) /*aggregrate function to sort disctincted line*/
{
final String uniqueWords = lines.collect(joining("\n"));
System.out.println("Final Output:" + uniqueWords);
Files.write(changedPath , uniqueWords.getBytes(),WRITE, TRUNCATE_EXISTING);
}
}
}
Read the text file using a BufferedReader and store it in a LinkedHashSet. Print it back out.
Here's an example:
public class DuplicateRemover {
public String stripDuplicates(String aHunk) {
StringBuilder result = new StringBuilder();
Set<String> uniqueLines = new LinkedHashSet<String>();
String[] chunks = aHunk.split("\n");
uniqueLines.addAll(Arrays.asList(chunks));
for (String chunk : uniqueLines) {
result.append(chunk).append("\n");
}
return result.toString();
}
}
Here's some unit tests to verify ( ignore my evil copy-paste ;) ):
import org.junit.Test;
import static org.junit.Assert.*;
public class DuplicateRemoverTest {
#Test
public void removesDuplicateLines() {
String input = "a\nb\nc\nb\nd\n";
String expected = "a\nb\nc\nd\n";
DuplicateRemover remover = new DuplicateRemover();
String actual = remover.stripDuplicates(input);
assertEquals(expected, actual);
}
#Test
public void removesDuplicateLinesUnalphabetized() {
String input = "z\nb\nc\nb\nz\n";
String expected = "z\nb\nc\n";
DuplicateRemover remover = new DuplicateRemover();
String actual = remover.stripDuplicates(input);
assertEquals(expected, actual);
}
}
Here's another solution. Let's just use UNIX!
cat MyFile.java | uniq > MyFile.java
Edit: Oh wait, I re-read the topic. Is this a legal solution since I managed to be language agnostic?
For better/optimum performance, it's wise to use Java 8's API features viz. Streams & Method references with LinkedHashSet for Collection as below:
import java.io.IOException;
import java.io.PrintWriter;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.LinkedHashSet;
import java.util.stream.Collectors;
public class UniqueOperation {
private static PrintWriter pw;
enter code here
public static void main(String[] args) throws IOException {
pw = new PrintWriter("abc.txt");
for(String p : Files.newBufferedReader(Paths.get("C:/Users/as00465129/Desktop/FrontEndUdemyLinks.txt")).
lines().
collect(Collectors.toCollection(LinkedHashSet::new)))
pw.println(p);
pw.flush();
pw.close();
System.out.println("File operation performed successfully");
}
here I'm using a hashset to store seen lines
Scanner scan;//input
Set<String> lines = new HashSet<String>();
StringBuilder strb = new StringBuilder();
while(scan.hasNextLine()){
String line = scan.nextLine();
if(lines.add(line)) strb.append(line);
}