I want to combine these two text files
Driver details text file:
AB11; Angela
AB22; Beatrice
Journeys text file:
AB22,Edinburgh ,6
AB11,Thunderdome,1
AB11,Station,5
And I want my output to be only the names and where the person has been. It should look like this:
Angela
Thunderdone
Station
Beatrice
Edinburgh
Here is my code. I'm not sure what i'm doing wrong but i'm not getting the right output.
ArrayList<String> names = new ArrayList<String>();
TreeSet<String> destinations = new TreeSet<String>();
public TaxiReader() {
BufferedReader brName = null;
BufferedReader brDest = null;
try {
// Have the buffered readers start to read the text files
brName = new BufferedReader(new FileReader("taxi_details.txt"));
brDest = new BufferedReader(new FileReader("2017_journeys.txt"));
String line = brName.readLine();
String lines = brDest.readLine();
while (line != null && lines != null ){
// The input lines are split on the basis of certain characters that the text files use to split up the fields within them
String name [] = line.split(";");
String destination [] = lines.split(",");
// Add names and destinations to the different arraylists
String x = new String(name[1]);
//names.add(x);
String y = new String (destination[1]);
destinations.add(y);
// add arraylists to treemap
TreeMap <String, TreeSet<String>> taxiDetails = new TreeMap <String, TreeSet<String>> ();
taxiDetails.put(x, destinations);
System.out.println(taxiDetails);
// Reads the next line of the text files
line = brName.readLine();
lines = brDest.readLine();
}
// Catch blocks exist here to catch every potential error
} catch (FileNotFoundException ex) {
ex.printStackTrace();
} catch (IOException ex) {
ex.printStackTrace();
// Finally block exists to close the files and handle any potential exceptions that can happen as a result
} finally {
try {
if (brName != null)
brName.close();
} catch (IOException ex) {
ex.printStackTrace();
}
}
}
public static void main (String [] args){
TaxiReader reader = new TaxiReader();
}
You are reading 2 files in parallel, I don't think that's gonna work too well. Try reading one file at a time.
Also you might want to rethink your data structures.
The first file relates a key "AB11" to a value "Angela". A map is better than an arraylist:
Map<String, String> names = new HashMap<String, String>();
String key = line.split(",")[0]; // "AB11"
String value = line.split(",")[1]; // "Angela"
names.put(key, value)
names.get("AB11"); // "Angela"
Similarly, the second file relates a key "AB11" to multiple values "Thunderdome", "Station". You could also use a map for this:
Map<String, List<String>> destinations = new HashMap<String, List<String>>();
String key = line.split(",")[0]; // "AB11"
String value = line.split(",")[1]; // "Station"
if(map.get(key) == null) {
List<String> values = new LinkedList<String>();
values.add(value);
map.put(key, values);
} else {
// we already have a destination value stored for this key
// add a new destination to the list
List<String> values = map.get(key);
values.add(value);
}
To get the output you want:
// for each entry in the names map
for(Map.Entry<String, String> entry : names.entrySet()) {
String key = entry.getKey();
String name = entry.getValue();
// print the name
System.out.println(name);
// use the key to retrieve the list of destinations for this name
List<String> values = destinations.get(key);
for(String destination : values) {
// print each destination with a small indentation
System.out.println(" " + destination);
}
}
Related
I want to find a key(to be taken from hashmap) in a file using java 8. If any key is found in the file it should print true. Below is my code
public static void main(String[] args) {
String fileName = "C:\\Users\\ABC\\Desktop\\Paper_R2_Final.txt";
Map<String, String> myMap = new HashMap<String,String>();
myMap.put("ecological", "myFirstKey");
myMap.put("Survey", "mySecondKey");
myMap.put("Worth", "myThirdKey");
//read file into stream, try-with-resources
try (Stream<String> stream = Files.lines(Paths.get(fileName),StandardCharsets.ISO_8859_1)) {
myMap.forEach((k,v)->System.out.println("key: " + k + ", value: " + v));
//Problem in the below line
System.out.println(stream.anyMatch(line->line.contains((CharSequence) myMap.keySet())));
} catch (IOException e) {
e.printStackTrace();
}
}
Try this:
public static void main(String[] args) {
String fileName = "C:\\Users\\ABC\\Desktop\\Paper_R2_Final.txt";
Map<String, String> myMap = new HashMap<String,String>();
myMap.put("ecological", "myFirstKey");
myMap.put("Survey", "mySecondKey");
myMap.put("Worth", "myThirdKey");
List<String> myList = new ArrayList<String>(myMap.keySet());
//if the line contains any of the keys
Predicate<String> p = (str) -> myList.stream().anyMatch(key -> str.contains(key));
//read file into stream, try-with-resources
try (Stream<String> stream = Files.lines(Paths.get(fileName),StandardCharsets.ISO_8859_1)) {
boolean foundAKey = stream.anyMatch(p);
if(foundAKey) {
//a key is found
}
} catch (IOException e) {
e.printStackTrace();
}
}
myMap.keySet() is giving you a Set, which is a collection. Casting it to a CharSequence makes no sense and will not give you what you are expecting.
One way of doing what you want would be to tokenize your line (for example split on the spaces), and check if your keySet contains the tokens one by one.
Some pseudo java code :
keySet = myMap.keySet();
for each line in the file {
tokens = line.split(" ");
for each token in tokens {
if keySet.contains(token) {
// Do whatever you want
}
}
}
Try this:
Files.lines(Paths.get(fileName), StandardCharsets.ISO_8859_1)
.anyMatch(line -> myMap.keySet().stream().anyMatch(line::contains));
public class CompareCSV {
public static void main(String args[]) throws FileNotFoundException, IOException {
String path = "C:\\csv\\";
String file1 = "file1.csv";
String file2 = "file2.csv";
String file3 = "file3.csv";
ArrayList<String> al1 = new ArrayList<String>();
ArrayList<String> al2 = new ArrayList<String>();
BufferedReader CSVFile1 = new BufferedReader(new FileReader("/C:/Users/bida0916/Desktop/macro.csv"));
String dataRow1 = CSVFile1.readLine();
while (dataRow1 != null) {
String[] dataArray1 = dataRow1.split(",");
for (String item1 : dataArray1) {
al1.add(item1);
}
dataRow1 = CSVFile1.readLine();
}
CSVFile1.close();
BufferedReader CSVFile2 = new BufferedReader(new FileReader("C:/Users/bida0916/Desktop/Deprecated.csv"));
String dataRow2 = CSVFile2.readLine();
while (dataRow2 != null) {
String[] dataArray2 = dataRow2.split(",");
for (String item2 : dataArray2) {
al2.add(item2);
}
dataRow2 = CSVFile2.readLine();
}
CSVFile2.close();
for (String bs : al2) {
al1.remove(bs);
}
int size = al1.size();
System.out.println(size);
try {
FileWriter writer = new FileWriter("C:/Users/bida0916/Desktop/NewMacro.csv");
while (size != 0) {
size--;
writer.append("" + al1.get(size));
writer.append('\n');
}
writer.flush();
writer.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
I want to compare two csv files in java and want to have the complete details removed of one csv file from the other by comparing the first column of both the files. Currently I am getting a csv file with one column only having all details jumbled up.
You are adding all values of all columns to a single list, that's why you get the mess in your output:
ArrayList<String> al1=new ArrayList<String>();
//...
String[] dataArray1 = dataRow1.split(",");
for (String item1:dataArray1)
{
al1.add(item1);
}
Add the complete string array from your file to your list, then you can access your data in a structured way:
List<String[]> al1 = new ArrayList<>();
//...
String[] dataArray1 = dataRow1.split(",");
al1.add(dataArray1);
But for removal of rows I'd recommend to use Maps for faster access, where the key is the element on which you decide which row to delete and the value is the full row from your cvs file:
Map<String, String> al1 = new HashMap<>(); // or LinkedHashMap if row order is relevant
//...
String[] dataArray1 = dataRow1.split(",");
al1.put(dataArray1[0], dataRow1);
But be aware, that if two rows in a file contain the same value in the first column, only one will be preserved. If that's possible you might need to adopt that solution to store the data in a Map<String, Set<String>> or Map<String, List<String>>.
At this point I'd like to recommend to extract the file-reading to a separate method, which you can reuse to read both of your input-files and reduce duplicate code:
Map<String, String> al1 = readInputCsvFile(file1);
Map<String, String> al2 = readInputCsvFile(file2);
For the deletion of the lines which shall be removed, iterate over the key set of one of the maps and remove the entry from the other:
for (String key : al2.keySet()) {
al1.remove(key);
}
And for writing your output file, just write the row read from the original file as stored in the 'value' of your map.
for (String dataRow : al1.values()) {
writer.append(dataRow);
writer.append('\n');
}
EDIT
If you need to perform operations based on other data columns you should rather store the 'split-array' in the map instead of the full-line string read from the file. Then you have all data columns separately available:
Map<String, String[]> al2 = new HashMap<>();
//...
String[] dataArray2 = dataRow2.split(",");
al2.put(dataArray2[0], dataArray2);
You might then, e.g. add a condition for deleting:
for (Entry<String, String[]> entry : al2.entrySet()) {
String[] data = entry.getValue();
if ("delete".equals(data[17])) {
al1.remove(entry.getKey());
}
}
For writing your output file you have to rebuild the csv-format.
I'd recommend to use Apache commons-lang StringUtils for that task:
for (String[] data : al1.values()) {
writer.append(StringUtils.join(data, ","));
writer.append('\n');
}
I have a long text file.
Now I will remove duplicates from the file. The problem is that the search parameter is the first word in the list, split by ":"
For example:
The file lines:
11234567:229283:29833204:2394803
11234567:4577546765:655776:564456456
43523:455543:54335434:53445
11234567:43455:544354:5443
Now I will have this here:
11234567:229283:29833204:2394803
43523:455543:54335434:53445
I need to get the first line from the duplicates, other will be ignored.
I tried this:
Set<String> lines11;
try (BufferedReader reader11 = new BufferedReader(new FileReader("test.txt"))) {
lines11 = new HashSet<>(10000); // maybe should be bigger
String line11;
while ((line11 = reader11.readLine()) != null) {
lines11.add(line11);
}
} // maybe should be bigger
try (BufferedWriter writer11 = new BufferedWriter(new FileWriter("test.txt"))) {
for (String unique : lines11) {
writer11.write(unique);
writer11.newLine();
}
}
That is working, but it removes only when the complete line is duplicated.
How can I change it so that it looks for the first word in every line and checks for duplicates here; when no duplicate is found, save the complete line; if duplicate then ignore the line?
You need to maintain a Set<String> that holds only the first word of each line.
List<String> lines11;
Set<String> dups;
try (BufferedReader reader11 = new BufferedReader(new FileReader("test.txt"))) {
lines11 = new ArrayList<>();
dups = new HashSet<>();
String line11;
while ((line11 = reader11.readLine()) != null) {
String first = line11.split(":")[0]; // assuming your separator is :
if (!dups.contains(first)) {
lines11.add(line11);
dups.add(first);
}
}
}
try (BufferedWriter writer11 = new BufferedWriter(new FileWriter("test.txt"))) {
for (String unique : lines11) {
writer11.write(unique);
writer11.newLine();
}
}
i will write the section about adding to list
use HashMap
String tmp[] = null;
HashMap<String, String> lines = new HashMap<String, String>();
String line11 = "";
while ((line11 = reader11.readLine()) != null) {
tmp = line11.split(":");
if(!lines.containsKey(tmp[0])){
lines.put(tmp[0], line11);
}
}
so the loop will add only uinuque lines , using first word as key
You can add the data in list and take one more set in which you will add first word in that set and try add every time first of new line if it is in set, then it will not be added and return false. On that basis you can add data in list or directly in you new bufferreader.
List<String> lines11;
Set<String> uniqueRecords;
try (BufferedReader reader11 = new BufferedReader(new FileReader("test.txt"))) {
lines11 = new ArrayList<>(); // no need to give size it will increase dynamically
uniqueRecords = new HashSet<>();
String line11;
while ((line11 = reader11.readLine()) != null) {
String firstWord = line11.substring(0, firstWord.firstIndexOf(" "));
if(uniqueRecords.add(firstWord )){
lines11.add(line11);
}
}
} // maybe should be bigger
try (BufferedWriter writer11 = new BufferedWriter(new FileWriter("test.txt"))) {
for (String unique : lines11) {
writer11.write(unique);
writer11.newLine();
}
}
The idea is to have a text file with information like:
FF0001 Red
FF0002 Blue
FF0003 Yellow
....
To pull this information and store it into a tree map.
This is my code so far...
public static void main(String[] args) {
File file = new File("test.txt");
TreeMap<String, String> colors = new TreeMap<String, String>();
BufferedReader br = null;
try {
FileReader fr = new FileReader(file);
br = new BufferedReader(fr);
String line;
String line1;
while ((line = br.readLine()) != null) {
String[] splited = line.split(" ");
for (String part : splited) {
colors.put(part, part);
}
}
Set<Map.Entry<String, String>> set = colors.entrySet();
for (Map.Entry<String, String> col : set) {
System.out.println(col.getKey() + " " + col.getValue());
}
} catch (FileNotFoundException e) {
System.out.println("File does not extist: " + file.toString());
} catch (IOException e) {
System.out.println("Unable to read file: " + file.toString());
} finally {
try {
br.close();
} catch (IOException e) {
System.out.println("Unable to close file: " + file.toString());
} catch (NullPointerException ex) {
// File was never properly opened
}
}
My output is:
FF0001 FF0001
FF0002 FF0002
FF0003 FF0003
Red Red
Blue Blue
Yellow Yellow
I am new to java collections and I need the information sorted which is why I choose a treemap, but I cannot seem to figure out why it is storing all information into the key and the value.
Thanks, first time poster here.
When you will split your line using space, it will generate two values for e.g. like "FF0001 Red"
it will have
splitted [0] = "FF0001" //id
splitted [1] = "Red" //color
and you are trying to store it like:
for (String part : splited) {
colors.put(part, part);//see you are storing same key and value so in above it case like key and value entry "FF0001" and another one for color.
}
Instead you need something like:
String id = splited[0];
String color = splited[1];
colors.put(id, color);
You have mistake in code
colors.put(part, part);
So you key and value in map are same.
You can write somethink like:
String[] splited = line.split("\\s+");
colors.put(splited[0], splited[1]);
And read this answer about split space:
How do I split a string with any whitespace chars as delimiters?
You need to remove the this for loop,
for (String part : splited) {
colors.put(part, part);
}
Instead directly use array index as key and value.
colors.put(splited[0], splited[1]);
To speed-up a lookup search into a multi-record file I wish to store its elements into a String array of array so that I can just search a string like "AF" into similar strings only ("AA", "AB, ... , "AZ") and not into the whole file.
The original file is like this:
AA
ABC
AF
(...)
AP
BE
BEND
(...)
BZ
(...)
SHORT
VERYLONGRECORD
ZX
which I want to translate into
AA ABC AF (...) AP
BE BEND (...) BZ
(...)
SHORT
VERYLONGRECORD
ZX
I don't know how much records there are and how many "elements" each "row" will have as the source file can change in the time (even if, after being read into memory, the array is only read).
I tried whis solution:
in a class I defined the string array of (string) arrays, without defining its dimensions
public static String[][] tldTabData;
then, in another class, I read the file:
public static void tldLoadTable() {
String rec = null;
int previdx = 0;
int rowidx = 0;
// this will hold each row
ArrayList<String> mVector = new ArrayList<String>();
FileInputStream fStream;
BufferedReader bufRead = null;
try {
fStream = new FileInputStream(eVal.appPath+eVal.tldTabDataFilename);
// Use DataInputStream to read binary NOT text.
bufRead = new BufferedReader(new InputStreamReader(fStream));
} catch (Exception er1) {
/* if we fail the 1.st try maybe we're working into some "package" (e.g. debugging)
* so we'll try a second time with a modified path (e.g. adding "bin\") instead of
* raising an error and exiting.
*/
try {
fStream = new FileInputStream(eVal.appPath +
"bin"+ File.separatorChar + eVal.tldTabDataFilename);
// Use DataInputStream to read binary NOT text.
bufRead = new BufferedReader(new InputStreamReader(fStream));
} catch (FileNotFoundException er2) {
System.err.println("Error: " + er2.getMessage());
er2.printStackTrace();
System.exit(1);
}
}
try {
while((rec = bufRead.readLine()) != null) {
// strip comments and short (empty) rows
if(!rec.startsWith("#") && rec.length() > 1) {
// work with uppercase only (maybe unuseful)
//rec.toUpperCase();
// use the 1st char as a row index
rowidx = rec.charAt(0);
// if row changes (e.g. A->B and is not the 1.st line we read)
if(previdx != rowidx && previdx != 0)
{
// store the (completed) collection into the Array
eVal.tldTabData[previdx] = mVector.toArray(new String[mVector.size()]);
// clear the collection itself
mVector.clear();
// and restart to fill it from scratch
mVector.add(rec);
} else
{
// continue filling the collection
mVector.add(rec);
}
// and sync the indexes
previdx = rowidx;
}
}
streamIn.close();
// globally flag the table as loaded
eVal.tldTabLoaded = true;
} catch (Exception er2) {
System.err.println("Error: " + er2.getMessage());
er2.printStackTrace();
System.exit(1);
}
}
When executing the program, it correctly accumulates the strings into mVector but, when trying to copy them into the eVal.tldTabData I get a NullPointerException.
I bet I have to create/initialize the array at some point but having problems to figure where and how.
First time I'm coding in Java... helloworld apart. :-)
you can use a Map to store your strings per row;
here something that you'll need :
//Assuming that mVector already holds all you input strings
Map<String,List<String>> map = new HashMap<String,List<String>>();
for (String str : mVector){
List<String> storedList;
if (map.containsKey(str.substring(0, 1))){
storedList = map.get(str.substring(0, 1));
}else{
storedList = new ArrayList<String>();
map.put(str.substring(0, 1), storedList);
}
storedList.add(str);
}
Set<String> unOrdered = map.keySet();
List<String> orderedIndexes = new ArrayList<String>(unOrdered);
Collections.sort(orderedIndexes);
for (String key : orderedIndexes){//get strings for every row
List<String> values = map.get(key);
for (String value : values){//writing strings on the same row
System.out.print(value + "\t"); // change this to writing to some file
}
System.out.println(); // add new line at the end of the row
}