This is my first post so sorry if I mess something up or if I am not clear enough. I have been looking through online forums for several hours and spend more trying to figure it out for myself.
I am reading information from a file and I need a loop that creates an ArrayList every time it goes through.
static ArrayList<String> fileToArrayList(String infoFromFile)
{
ArrayList<String> smallerArray = new ArrayList<String>();
//This ArrayList needs to be different every time so that I can add them
//all to the same ArrayList
if (infoFromFile != null)
{
String[] splitData = infoFromFile.split(":");
for (int i = 0; i < splitData.length; i++)
{
if (!(splitData[i] == null) || !(splitData[i].length() == 0))
{
smallerArray.add(splitData[i].trim());
}
}
}
The reason I need to do this is that I am creating an app for a school project that reads questions from a delimited text file. I have a loop earlier that reads one line at a time from the text. I will insert that string into this program.
How do I make the ArrayList smallerArray a separate ArrayList everytime it goes through this method?
I need this so I can have an ArrayList of each of these ArrayList
Here is a sample code of what you intend to do -
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.stream.Stream;
public class SimpleFileReader {
private static final String DELEMETER = ":";
private String filename = null;
public SimpleFileReader() {
super();
}
public SimpleFileReader(String filename) {
super();
setFilename(filename);
}
public String getFilename() {
return filename;
}
public void setFilename(String filename) {
this.filename = filename;
}
public List<List<String>> getRowSet() throws IOException {
List<List<String>> rows = new ArrayList<>();
try (Stream<String> stream = Files.lines(Paths.get(filename))) {
stream.forEach(row -> rows.add(Arrays.asList(row.split(DELEMETER))));
}
return rows;
}
}
And, here is the JUnit test for the above code -
import static org.junit.jupiter.api.Assertions.fail;
import java.io.IOException;
import java.util.List;
import org.junit.jupiter.api.Test;
public class SimpleFileReaderTest {
public SimpleFileReaderTest() {
super();
}
#Test
public void testFileReader() {
try {
SimpleFileReader reader = new SimpleFileReader("c:/temp/sample-input.txt");
List<List<String>> rows = reader.getRowSet();
int expectedValue = 3; // number of actual lines in the sample file
int actualValue = rows.size(); // number of rows in the list
if (actualValue != expectedValue) {
fail(String.format("Expected value for the row count is %d, whereas obtained value is %d", expectedValue, actualValue));
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
Related
I was trying to read some words from a text file and then arrange them into descending array.
I reached the point where I read the words successfully,stored the words in a array, and when I went ahead to arrange it into descending form I noticed that my array also contained some null values.
When I tried to remove the null values using (complete code below)
Arrays.stream(w.words).filter(x->x != null).toArray(); , it still didn't worked.
After trying for quite some time now I think I need some help here.
Code,text file and output at this stage is as follows:
`
import java.io.BufferedReader;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.HashSet;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.Objects;
import java.util.Random;
import java.util.Scanner;
import java.util.Set;
import java.util.stream.Collectors;
public class Practise {
private Scanner fp;
private Scanner scanLine;
private String[] words = new String[6] ;
int count;
String temp;
String [][] samewords;
int size;
String[] words_sorted;
public Practise() {
openFile();
readFile();
printa();
}
private void openFile() {
try {
fp = new Scanner(new File ("D:\\workspace\\file.txt"));
}
catch (Exception e) {
System.out.println("File does not exist");
}
}
private void readFile() {
try {
count = 0;
while (fp.hasNextLine()) {
String strLine = fp.nextLine();
scanLine = new Scanner(strLine);
words[count] = scanLine.next();
System.out.println("Here2"+words[count]);
System.out.println();
count++;
}
}
catch (Exception e) {
System.err.print("Error: " + e.getMessage());
}
}
private void printa() {
try (BufferedReader br = new BufferedReader(new FileReader("D:\\workspace\\file.txt"))) {
size = findLongestWords();
samewords = new String[size][size];
String line;
int i = 0;
String [] temp;
while ((line = br.readLine()) != null) {
temp = line.split(",");
for (int j = 0; j < samewords[i].length; j++) {
samewords[i][j] = temp[j];
System.out.println(samewords[i][j]);
}
i++;
}
//System.out.println(answers[1][2]);
} catch (IOException e) {
e.printStackTrace();
}
}
public int findLongestWords() throws FileNotFoundException {
int longest_word = 0;
int current;
BufferedReader sc = new BufferedReader(new FileReader("D:\\workspace\\file.txt"));
String li;
String[] tr;
try {
while ((li = sc.readLine())!= null ) {
tr = li.split(",");
current = tr.length;
if (current > longest_word) {
longest_word = current;
}
}
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
System.out.println("\n"+longest_word+"\n");
return longest_word;
}
private String[] sort(String[] string) {
/*Local variables*/
Map<String, Integer> map=new LinkedHashMap<String, Integer>();
Map<String, Integer> mapCopy=new LinkedHashMap<String, Integer>();
int [] lengthsArray=new int[string.length];
String [] sortedStrings=new String[string.length];
int counter1=0;
int counter2=0;
/* Store all the pairs <key,value>
* i.e <string[i],string[i].length>
*/
for(String s:string) {
System.out.println(s);
map.put((String) s, s.length());
lengthsArray[counter1]= s.length();//store all the lengths
counter1++;
}
mapCopy=new LinkedHashMap<String, Integer>(map);//make a copy of map
Arrays.sort(lengthsArray);//sort the array of lengths
/*
* Sort array according to the array of lengths
* by finding the matching value from the map
* then add it to the final string array,and then remove it from the map
*/
for(int item:lengthsArray) {
for(Map.Entry<String, Integer> e:map.entrySet()) {
if(item==e.getValue()) {
sortedStrings[counter2]=e.getKey();
counter2++;
map.remove(e.getKey());
break;
}
}
}
map=mapCopy;
System.out.println(map);//print map
return sortedStrings;
}
public static void main(String[] args) {
Practise w = new Practise();
System.out.println(Arrays.toString(w.words));
w.sort(w.words);
}
}
`
file.txt is:
ACT,CAT,AT,RAT,PAT,TAT
output is:
Here2ACT,CAT,AT,RAT,PAT,TAT
6
ACT
CAT
AT
RAT
PAT
TAT
[ACT,CAT,AT,RAT,PAT,TAT, null, null, null, null, null]
ACT,CAT,AT,RAT,PAT,TAT
null
Exception in thread "main" java.lang.NullPointerException
at Practise.sort(Practise.java:190)
at Practise.main(Practise.java:239)
null is because of the word array which you have declared ( predefined size ). Probably you can change that and use ArrayList (as it can be of dynamic size) instead of an String array, which can help you resolve. Just to help you, follow below changes:
private List<String> words = new ArrayList<>();
/*update below line in readFile() instead of words[count] = scanLine.next();*/
words.add(scanLine.next());
Change method signature sort(List<String> string)
//also update below declarations
int[] lengthsArray = new int[string.size()];
String[] sortedStrings = new String[string.size()];
change Arrays.toString(w.words) to just w.words in print statement
Hope this helps. Everything looks good.
So the code below finds words in a document as specific by the word input. Counts the number of times the words occurs in each sentence then stores that count in the arraylists at the bottom label a for cone and b for ctwo.
I want to use the arraylists in another class but can't seem to find a way to do it.
import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
public class exc {
public exc() {
}
public static void main(String[] args) throws Exception {
cone aa = new cone();
ctwo bb = new ctwo();
// after this I'm stuck
}
}
import java.io.BufferedReader;
import java.io.FileReader;
import java.util.Arrays;
import java.util.List;
public class cone {
public void cone() throws Exception {
BufferedReader e = new BufferedReader(new FileReader("words to be read.txt"));
String o;
while((o = e.readLine()) != null){
String[] sentences = o.split("\\b[.!?]\\s+");
//System.out.println(o);
String [] h = sentences;
{
BufferedReader t = new BufferedReader(new FileReader("Text to be scan.txt"));
String g;
while((g = t.readLine()) != null){
String[] set=g.split(" ");
List<String> list = Arrays.asList(set);
// System.out.println(Arrays.toString(set));
//System.out.println(o);
int sentenceNumb=1;
for (String sentence: h) {
int counter=0;
String[] words = sentence.replace(".", "").split(" ");
for(String word: words) {
if (list.contains(word)) {
counter++;
}
}
List<Integer> A = Arrays.asList(counter++);
}
}
}
}
}
}
import java.io.BufferedReader;
import java.io.FileReader;
import java.util.Arrays;
import java.util.List;
public class ctwo {
public void ctwo() throws Exception {
BufferedReader e = new BufferedReader(new FileReader("words to be read.txt"));
String o;
while((o = e.readLine()) != null){
String[] sentences = o.split("\\b[.!?]\\s+");
//System.out.println(o);
String [] h = sentences;
{
BufferedReader t = new BufferedReader(new FileReader("Text to be scan.txt"));
String g;
while((g = t.readLine()) != null){
String[] set=g.split(" ");
List<String> list = Arrays.asList(set);
// System.out.println(Arrays.toString(set));
//System.out.println(o);
int sentenceNumb=1;
for (String sentence: h) {
int counter=0;
String[] words = sentence.replace(".", "").split(" ");
for(String word: words) {
if (list.contains(word)) {
counter++;
}
}
List<Integer> B= Arrays.asList(counter++);
}
}
}
}
}
}
Best approach: You have both the ArrayLists in main(), pass them as function parameters to functions(from any class) that need them.
Not so good approach: Store the ArrayLists as package protected static class variables in the cone and ctwo classes. You can access them as cone.A and ctwo.B.
Pass the same array list in the constructor of both the classes.
your program seems weird.
I would suggest reading words and adding distinct words to hashmap with key as word and value as it's count.
I'm a new french user on stack and I have a problem ^^
I use an HTML parse Jsoup for parsing a html page. For that it's ok but I can't parse more url in same time.
This is my code:
first class for parsing a web page
package test2;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.ss.usermodel.Sheet;
import org.apache.poi.ss.usermodel.Workbook;
import org.jsoup.Jsoup;
import org.jsoup.nodes.Document;
import org.jsoup.select.Elements;
public final class Utils {
public static Map<String, String> parse(String url){
Map<String, String> out = new HashMap<String, String>();
try
{
Document doc = Jsoup.connect(url).get();
doc.select("img").remove();
Elements denomination = doc.select(".AmmDenomination");
Elements composition = doc.select(".AmmComposition");
Elements corptexte = doc.select(".AmmCorpTexte");
for(int i = 0; i < denomination.size(); i++)
{
out.put("denomination" + i, denomination.get(i).text());
}
for(int i = 0; i < composition.size(); i++)
{
out.put("composition" + i, composition.get(i).text());
}
for(int i = 0; i < corptexte.size(); i++)
{
out.put("corptexte" + i, corptexte.get(i).text());
System.out.println(corptexte.get(i));
}
} catch(IOException e){
e.printStackTrace();
}
return out;
}//Fin Methode parse
public static void excelizer(int fileId, Map<String, String> values){
try
{
FileOutputStream out = new FileOutputStream("C:/Documents and Settings/c.bon/git/clinsearch/drugs/src/main/resources/META-INF/test/fichier2.xls" );
Workbook wb = new HSSFWorkbook();
Sheet mySheet = wb.createSheet();
Row row1 = mySheet.createRow(0);
Row row2 = mySheet.createRow(1);
String entete[] = {"CIS", "Denomination", "Composition", "Form pharma", "Indication therapeutiques", "Posologie", "Contre indication", "Mise en garde",
"Interraction", "Effet indesirable", "Surdosage", "Pharmacodinamie", "Liste excipients", "Incompatibilité", "Duree conservation",
"Conservation", "Emballage", "Utilisation Manipulation", "TitulaireAMM"};
for (int i = 0; i < entete.length; i++)
{
row1.createCell(i).setCellValue(entete[i]);
}
Set<String> set = values.keySet();
int rowIndexDenom = 1;
int rowIndexCompo = 1;
for(String key : set)
{
if(key.contains("denomination"))
{
mySheet.createRow(1).createCell(1).setCellValue(values.get(key));
rowIndexDenom++;
}
else if(key.contains("composition"))
{
row2.createCell(2).setCellValue(values.get(key));
rowIndexDenom++;
}
}
wb.write(out);
out.close();
}
catch(Exception e)
{
e.printStackTrace();
}
}
}
second class
package test2;
public final class Task extends Thread {
private static int fileId = 0;
private int id;
private String url;
public Task(String url)
{
this.url = url;
id = fileId;
fileId++;
}
#Override
public void run()
{
Utils.excelizer(id, Utils.parse(url));
}
}
the main class (entry point)
package test2;
import java.util.ArrayList;
public class Main {
public static void main(String[] args)
{
ArrayList<String> urls = new ArrayList<String>();
urls.add("http://base-donnees-publique.medicaments.gouv.fr/affichageDoc.php?specid=61266250&typedoc=R");
urls.add("http://base-donnees-publique.medicaments.gouv.fr/affichageDoc.php?specid=66207341&typedoc=R");
for(String url : urls)
{
new Task(url).run();
}
}
}
When the data was copied to my excel file, the second url doesn't work.
Can you help me solve my problem please?
Thanks
I think its because your main() exits before your second thread has a chance to do its job. You should wait for all spawned threads to complete using Thread.join(). Or better yet, create one of the ExecutorService's and use awaitTermination(...) to block until all URLs are parsed.
EDIT See some examples here http://www.javacodegeeks.com/2013/01/java-thread-pool-example-using-executors-and-threadpoolexecutor.html
How would I go about saving a String Vector to a file every time it is edited?
So let's say I have usernames in a vector, after I add or delete a username I'd like it to save that vector so if the program is closed, it will show the most recent elements.
This should help you get started.
As JB Nizet said, you should use an ArrayList.
I also went ahead and used Java 7 autocloseable functionality, which ensures you close file handles appropriately.
Of course, you will need to validate your input, and you will want to take care about what you persist. I suspect that you will soon want to consider a better storage strategy, however, this will get you started.
In addition, since this is acting like a collection, you should add hashcode and equals. For brevity sake, I did not add those.
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.io.Writer;
import java.util.ArrayList;
import java.util.List;
public class PersistedCollection {
private static final String NEWLINE_SEPARATOR = System.getProperty("line.separator");
private final List<String> values;
private final File file;
public PersistedCollection(File file) {
this.values = new ArrayList<>();
this.file = file;
}
public void add(String value) {
// You should validate this value. Remove carriage returns, make sure it meets your value specifications.
values.add(value);
persist();
}
public void remove(String value) {
values.remove(value);
persist();
}
private void persist() {
// Using Java 7 autocloseable to ensure that the output stream is closed, even in exceptional circumstances.
try (OutputStream outputStream = new BufferedOutputStream(new FileOutputStream(this.file), 8192); Writer writer = new PrintWriter(outputStream)) {
for (String value : values) {
writer.append(value);
writer.append(NEWLINE_SEPARATOR);
}
} catch (IOException e) {
e.printStackTrace();
}
}
#Override
public String toString() {
StringBuilder builder = new StringBuilder();
builder.append("PersistedCollection [values=");
builder.append(values);
builder.append(", file=");
builder.append(file);
builder.append("]");
return builder.toString();
}
public static void main(String[] arguments) {
PersistedCollection persistedCollection = new PersistedCollection(new File("/tmp/test.txt"));
persistedCollection.add("jazeee");
persistedCollection.add("temporary user");
persistedCollection.add("user402442");
persistedCollection.add("JB Nizet");
persistedCollection.remove("temporary user");
System.out.println(persistedCollection);
}
}
Another solution would be to create a class where you add all the methods required to read from a file of usernames (one username per line). Then you can refer to this class from anywhere (as the modifier is public) and call the methods such that you will add or remove usernames from that file.
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.util.ArrayList;
import java.io.File;
public class Test {
private static BufferedWriter bw;
private static ArrayList<String> vector=new ArrayList<String>();
private static String everything;
//add an username
public static void add(String x){
vector.add(x);
}
//remove an username
public static void remove(String x){
vector.remove(x);
}
//update the file with the new vector of usernames
public static void updateToFile() throws IOException{
File username = new File("/home/path/to/the/file");
FileWriter fw = new FileWriter(username.getAbsoluteFile());
bw= new BufferedWriter(fw);
for (String x:vector){
bw.write(x.toString());
bw.write("\n");
}
bw.close();
}
//you call this method to initialise your vector of usernames
//this implies that you already have a file of usernames
//one username per line
public static void setUsername() throws IOException{
vector=new ArrayList<String>();
BufferedReader br = new BufferedReader(new FileReader("/home/path/to/the/file"));
try {
StringBuilder sb = new StringBuilder();
String line = br.readLine();
while (line != null) {
sb.append(line);
sb.append(System.lineSeparator());
line = br.readLine();
}
everything = sb.toString();
} finally {
br.close();
}
String lines[] = everything.split("\\r?\\n");
for (String x:lines){
vector.add(x);
}
}
//print your usernames in the console
public static void printUsers(){
for (String User:vector){
System.out.println(User);
}
}
}
Then it gets as easy as this:
import java.io.IOException;
public class MainTest {
public static void main(String[] args) throws IOException{
Test.setUsername();
Test.printUsers();
Test.add("username5");
Test.remove("username2");
System.out.println("// add username5; remove username2");
Test.printUsers();
System.out.println("// file has been updated with the new state");
Test.updateToFile();
System.out.println("// veryfing update");
Test.setUsername();
Test.printUsers();
}
}
The output:
(this first 4 users is what I have in the file)
username1
username2
username3
username4
// add username5; remove username2
username1
username3
username4
username5
// file has been updated with the new state
// verifying update
username1
username3
username4
username5
I wanted to make a way so that I can load all the Images in my source folder without having to code each line for each image, but I keep getting an error and have tried different ways to do this and I still can't figure it out. Is it just impossible?
Here is how it works: I save all the images I am going to need on a text file (in this case startUp.txt), then I store the lines in the text file in a linked-list(String) then I use a loop to get the images and store those in a linked-list(Image) so that I don't need to write code for every single Image to load.
Here is my code:
package com.game.task;
import java.awt.Image;
import java.io.File;
import java.io.FileNotFoundException;
import java.util.LinkedList;
import java.util.Scanner;
import javax.swing.ImageIcon;
public class imagesTest {
public LinkedList<Image> storeImages = new LinkedList<Image>();
private LinkedList<String> storeStrings = new LinkedList<String>();
public imagesTest() {
load();
readimage();
}
public void readimage() {
for(int index = 0; index < storeStrings.size(); index++){
Image temp = new ImageIcon(this.getClass().getClassLoader().getResource("/res/"+storeStrings.get(index))).getImage();
storeImages.add(temp);
}
}
private void load() {
File file = new File("Data/startUp.txt");
try {
Scanner read = new Scanner(file);
while (read.hasNextLine()) {
storeStrings.add(read.nextLine());
}
} catch (FileNotFoundException e) {
e.printStackTrace();
}
}
public static void main(String[] arsg) {
imagesTest t = new imagesTest();
}
}
Exception:
Exception in thread "main" java.lang.NullPointerException
at javax.swing.ImageIcon.<init>(ImageIcon.java:217)
at com.game.task.imagesTest.readimage(imagesTest.java:24)
at com.game.task.imagesTest.load(imagesTest.java:41)
at com.game.task.imagesTest.<init>(imagesTest.java:17)
at com.game.task.imagesTest.main(imagesTest.java:45)
I found a way to loop through the resource folder and it was not that hard.
All i had to do use make a method and keep calling it in a loop here is the code
package com.game.task;
import java.awt.Image;
import java.io.File;
import java.io.FileNotFoundException;
import java.util.LinkedList;
import java.util.Scanner;
import javax.swing.ImageIcon;
public class imagesTest {
public LinkedList<Image> storeImages = new LinkedList<Image>();
private LinkedList<String> storeStrings = new LinkedList<String>();
public imagesTest() {
load();
start();
}
public void readimage(String f) {
Image temp = new ImageIcon(this.getClass().getResource("/res/"+f)).getImage();//looks for it
storeImages.add(temp);//put it in a linked-List(Image)
}
public void start(){
for(int index = 0; index < storeStrings.size(); index++){
readimage(storeStrings.get(index));//calling the methode to look in resource folder
}
}
//reads the text file and puts the out put in a linked-list(String)
private void load() {
File file = new File("Data/startUp.txt");
try {
Scanner read = new Scanner(file);
while (read.hasNextLine()) {
storeStrings.add(read.nextLine());
}
} catch (FileNotFoundException e) {
e.printStackTrace();
}
}
public static void main(String[] arsg) {
imagesTest t = new imagesTest();
}
}