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I'm trying to extract a certain character from a buffer that isn't ASCII. I'm reading in a file that contains movie names that have some non ASCII character sprinkled in it like so.
1|Tóy Story (1995)
2|GoldenEye (1995)
3|Four Rooms (1995)
4|Gét Shorty (1995)
I was able to pick off the lines that contained the non ASCII characters, but I'm trying to figure out how to get that particular character from the lines that have said non ASCII character and replace it with an ACSII character from the map I've made.
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
public class Main {
public static void main(String[] args) {
HashMap<Character, Character>Char_Map = new HashMap<>();
Char_Map.put('o','ó');
Char_Map.put('e','é');
Char_Map.put('i','ï');
for(Map.Entry<Character,Character> entry: Char_Map.entrySet())
{
System.out.println(entry.getKey() + " -> "+ entry.getValue());
}
try
{
BufferedReader br = new BufferedReader(new FileReader("movie-names.txt"));
String contentLine= br.readLine();
while(contentLine != null)
{
String[] contents = contentLine.split("\\|");
boolean result = contents[1].matches("\\A\\p{ASCII}*\\z");
if(!result)
{
System.out.println(contentLine);
//System.out.println();
}
contentLine= br.readLine();
}
}
catch (IOException ioe)
{
System.out.println("Cannot open file as it doesn't exist");
}
}
}
I tried using something along the lines of:
if((contentLine.charAt(i) == something
But I'm not sure.
You can just use replaceAll. Put this in the while loop, so that it works on each line you read from the file. With this change, you won't need the split and if (... matches) anymore.
contentLine.replaceAll("ó", "o");
contentLine.replaceAll("é", "e");
contentLine.replaceAll("ï", "i");
If you want to keep a map, just iterate over its keys and replace with the values you want to map to:
Map<String, String> map = new HashMap<>();
map.put("ó", "o");
// ... and all the others
Later, in your loop reading the contents, you replace all the characters:
for (Map.Entry<String, String> entry : map.entrySet())
{
String oldChar = entry.getKey();
String newChar = entry.getValue();
contentLine = contentLine.replaceAll(oldChar, newChar);
}
Here is a complete example:
import java.io.BufferedReader;
import java.io.FileReader;
import java.util.HashMap;
import java.util.Map;
public class Main {
public static void main(String[] args) throws Exception {
HashMap<String, String> nonAsciiToAscii = new HashMap<>();
nonAsciiToAscii.put("ó", "o");
nonAsciiToAscii.put("é", "e");
nonAsciiToAscii.put("ï", "i");
BufferedReader br = new BufferedReader(new FileReader("movie-names.txt"));
String contentLine = br.readLine();
while (contentLine != null)
{
for (Map.Entry<String, String> entry : nonAsciiToAscii.entrySet())
{
String oldChar = entry.getKey();
String newChar = entry.getValue();
contentLine = contentLine.replaceAll(oldChar, newChar);
}
System.out.println(contentLine); // or whatever else you want to do with the cleaned lines
contentLine = br.readLine();
}
}
}
This prints:
robert:~$ javac Main.java && java Main
1|Toy Story (1995)
2|GoldenEye (1995)
3|Four Rooms (1995)
4|Get Shorty (1995)
robert:~$
You want to flip your keys and values:
Map<Character, Character> charMap = new HashMap<>();
charMap.put('ó','o');
charMap.put('é','e');
charMap.put('ï','i');
and then get the mapped character:
char mappedChar = charMap.getOrDefault(inputChar, inputChar);
To get the chars for a string, call String#toCharArray()
I have a little problem of understanding, I will put the code here and try to explain my problem.
I have a first class, ReadSymptomFromDataFile :
package com.hemebiotech.analytics;
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
/**
* Simple brute force implementation
*
*/
public class ReadSymptomDataFromFile implements ISymptomReader {
private final String filepath;
/**
*
* #param filepath a full or partial path to file with symptom strings in it, one per line
*/
public ReadSymptomDataFromFile (String filepath) {
this.filepath = filepath;
}
#Override
public List<String> getSymptoms () {
ArrayList<String> result = new ArrayList<>();
if (filepath != null) {
try {
BufferedReader reader = new BufferedReader (new FileReader(filepath));
String line = reader.readLine();
while (line != null) {
result.add(line);
line = reader.readLine();
}
reader.close();
} catch (IOException e) {
e.printStackTrace();
}
}
return result;
}
}
This class is used to read a txt file which contains a list of symptoms, with several times the same symptoms inside, hence the value of the TreeMap, a symptom associated with the number of times it appears. (Value, Key)
So far so good.
Then I have this code that I made myself but it happens from the class ReadSymptomData :
package com.hemebiotech.analytics.Test;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.util.*;
public class MainAppTest2 {
public static void main (String[] args) {
try {
File file = new File ("Project02Eclipse\\symptoms.txt");
Scanner scan = new Scanner (file);
Map<String, Integer> wordCount = new TreeMap<> ();
while (scan.hasNext ()) {
String word = scan.next ();
if (!wordCount.containsKey (word)) {
wordCount.put (word, 1);
} else {
wordCount.put (word, wordCount.get (word) + 1);
}
}
// Result in console & Write file output
FileWriter writer = new FileWriter ("resultat2.out");
BufferedWriter out = new BufferedWriter (writer);
for (Map.Entry<String, Integer> entry : wordCount.entrySet ()) {
System.out.println ("Valeur: " + entry.getKey () + "| Occurence: " + entry.getValue ());
out.write (entry.getKey () + " = " + entry.getValue () + " \n");
out.flush (); // Force write
}
} catch (IOException e) {
System.out.println ("Fichier introuvable");
}
}
}
This code does much the same thing, it reads a txt file, saves it in a TreeMap, displays it on the console and saves it in a resultat file.
Now my problem is that I am trying to split my code into several classes while using the already existing class ReadSymptomData, one class to read the text file, another to convert it all to TreeMap, another class to write the results in an output file, and a final one for exception handling.
I started with this FileToTreeMap class, but it's ugly, it's not clean, and I'm sure it can be done better to convert my ReadSymptomDataFromFile object to a TreeMap:
package com.hemebiotech.analytics.Test.read;
import com.hemebiotech.analytics.ReadSymptomDataFromFile;
import java.util.*;
public class FileToTreeMap {
// Read file
public Map<String, Integer> readFile () {
ReadSymptomDataFromFile list = new ReadSymptomDataFromFile ("Project02Eclipse\\symptoms.txt");
Map<String, Integer> listSort = new TreeMap<> ();
ArrayList<String> test = new ArrayList<> (list.getSymptoms ());
Scanner scan = new Scanner (String.valueOf (test));
while (scan.hasNext ()) {
String word = scan.next ();
if (!listSort.containsKey (word)) {
listSort.put (word, 1);
} else {
listSort.put (word, listSort.get (word) + 1);
}
}
for (Map.Entry<String, Integer> entry : listSort.entrySet ()) {
System.out.println ("Valeur: " + entry.getKey () + " Occurence: " + entry.getValue ());
}
return listSort;
}
}
Here, I am a little lost in cutting my code, and the main problem I have is to convert my ArrayList to a TreeMap.
Sorry for the length of the post, but I would appreciate any help I get, thanks in advance.
To convert a list into a map, what you can do is use a for loop, which goes through the list and adds each item one by one:
ReadSymptomDataFromFile list = new ReadSymptomDataFromFile("Project02Eclipse\\symptoms.txt");
Map<String, Integer> listSort = new TreeMap<>();
List<String> test = list.getSymptoms();
for (String word : test) {
if (!listSort.containsKey(word)) {
listSort.put(word, 1);
} else {
listSort.put(word, listSort.get(word) + 1);
}
}
Try in Java 8
final List<String> symptomList;
final Map<String, Integer> countedSymptoms;
symptoms.forEach((symptom) ->
countedSymptoms.put(symptom, Collections.frequency(symptomList, symptom)));
You iterate through list and put the elements in the map. Since this is an arrayList duplicate elements would stay. But beforehand couldn't get why you have to read some data to a list and some to treeMap? You have already been loading your symptoms data to a treeMap. So the code stub is more like
for(String el : test) {
if(!listSort.containsKey(el))
listSort.put(el,1);
else
listSort.put(el, listSort.get(el)+1));
}
You could use the merge method of Map:
List<String> symptoms = List.of("a", "b", "c", "b", "c", "a", "b", "b", "c");
Map<String, Integer> counts = new TreeMap<>();
symptoms.forEach(s -> counts.merge(s, 1, Integer::sum));
counts.forEach((k, v) -> System.out.println(k + ": " + v));
This prints:
a: 2
b: 4
c: 3
I have a CSV file with this content:
2017-10-29 00:00:00.0,"1005",-10227,0,0,0,332894,0,0,222,332894,222,332894 2017-10-29 00:00:00.0,"1010",-125529,0,0,0,420743,0,0,256,420743,256,420743 2017-10-29 00:00:00.0,"1005",-10227,0,0,0,332894,0,0,222,332894,222,332894 2017-10-29 00:00:00.0,"1013",-10625,0,0,-687,599098,0,0,379,599098,379,599098 2017-10-29 00:00:00.0,"1604",-1794.9,0,0,-3.99,4081.07,0,0,361,4081.07,361,4081.07
So lines 1 and 3 are duplicates.
Now I want to read the file in and print out duplicate lines in the console.
I set up this Java code reading the file in and throwing it line by line into an ArrayList. Then I create an immutable
copy, loop through the ArrayList and in the binarySearch I use the immutable copy of the ArrayList:
import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
public class ReadValidationFile {
public static void main(String[] args) {
List<String> validationFile = new ArrayList<>();
try(BufferedReader br = new BufferedReader(new FileReader("validation_small.csv"));){
String line;
while((line = br.readLine())!= null){
validationFile.add(line);
}
} catch (FileNotFoundException e) {
//e.printStackTrace();
System.out.println("file not found " + e.getMessage());
} catch (IOException e) {
e.printStackTrace();
}
List<String> validationFileCopy = Collections.unmodifiableList(validationFile);
for(String line : validationFile){
int comp = Collections.binarySearch(validationFileCopy,line,new ComparatorLine());
if (comp <= 0){
System.out.println(line);
}
}
}
}
Comparator Class:
import java.util.Comparator;
public class ComparatorLine implements Comparator<String> {
#Override
public int compare(String s1, String s2) {
return s1.compareToIgnoreCase(s2);
}
}
I expect this line to be printed:
2017-10-29 00:00:00.0,"1005",-10227,0,0,0,332894,0,0,222,332894,222,332894
But the output I get is this:
2017-10-29 00:00:00.0,"1010",-125529,0,0,0,420743,0,0,256,420743,256,420743
Can you help me please to see what I am doing wrong? My comparator I think is okay. What is wrong with my
ArrayLists?
The other answer(s) correctly state that you should be using Set instead of List. But for the sake of learning, let's have a look at your code and see where you went wrong.
public class ReadValidationFile {
public static void main(String[] args) {
List<String> validationFile = new ArrayList<>();
try(BufferedReader br = new BufferedReader(new FileReader("validation_small.csv"));){
Semicolon is unnecessary.
String line;
while((line = br.readLine())!= null){
validationFile.add(line);
}
This can all be achieved in just one line: List<String> validationFile = Files.readAllLines(Paths.get("validation_small.csv"), "utf-8");
} catch (FileNotFoundException e) {
//e.printStackTrace();
System.out.println("file not found " + e.getMessage());
} catch (IOException e) {
e.printStackTrace();
}
List<String> validationFileCopy = Collections.unmodifiableList(validationFile);
Actually, this is not a copy. It is just an unmodifiable view of the same list.
for(String line : validationFile){
int comp = Collections.binarySearch(validationFileCopy,line,new ComparatorLine());
You might as well just search validationFile itself. However, you are calling binarySearch which only works on sorted lists, but your list is not sorted. See documentation.
if (comp <= 0){
System.out.println(line);
}
You are printing when it's not found (comp <= 0). If the search succeeds, it will return a non-negative number (comp >= 0). But another problem is that you are searching the whole list for each element, and the search will obviously always succeed (that is, if your list was sorted).
Save yourself all the trouble and use a Set instead. And, using Java 8 streams, the whole program can be reduced to the following:
public static void main(String[] args) throws Exception {
Set<String> uniqueLines = new HashSet<>();
Files.lines(Paths.get("", "utf-8"))
.filter(line -> !uniqueLines.add(line))
.forEach(System.out::println);
}
If you really need to ignore case when comparing strings (from your given data, it looks like it doesn't make any difference since it's just numbers), then store each unique line by first uppercasing and then lowercasing it. This apparently cumbersome technique is necessary because just lowercasing is not enough if dealing with non-English language text. The equalsIgnoreCase method also does this.
public static void main(String[] args) throws Exception {
Set<String> uniqueLines = new HashSet<>();
Files.lines(Paths.get("", "utf-8"))
.filter(line -> !uniqueLines.add(line.toUpperCase().toLowerCase()))
.forEach(System.out::println);
}
Create a Set while reading lines from the input csv file, anytime add() element to set returns false print the line as it is duplicate line.
If you want list of all duplicate lines then create a List which will have lines that returned false when tried add() to Set.
NOTE:
I have simulated your file reading by using a static data.
Small note, if your data only contains numbers and no alphabets then you do not need case-insensitive comparison.
If your data contains alphabets then also you do not need a special Comparator as you can insert data into Set using add(line.toLowerCase()) which will ensure that all lines are compared with lower case and then added to Set.
import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
import java.util.stream.Collectors;
public class ReadValidationFile {
static List<String> validationFile = new ArrayList<>();
static {
validationFile.add("2017-10-29 00:00:00.0,\"1005\",-10227,0,0,0,332894,0,0,222,332894,222,332894");
validationFile.add("2017-10-29 00:00:00.0,\"1010\",-125529,0,0,0,420743,0,0,256,420743,256,420743");
validationFile.add("2017-10-29 00:00:00.0,\"1005\",-10227,0,0,0,332894,0,0,222,332894,222,332894");
validationFile.add("2017-10-29 00:00:00.0,\"1013\",-10625,0,0,-687,599098,0,0,379,599098,379,599098");
validationFile.add("2017-10-29 00:00:00.0,\"1604\",-1794.9,0,0,-3.99,4081.07,0,0,361,4081.07,361,4081.07");
}
public static void main(String[] args) {
// Option 1 : unique lines only
Set<String> uniqueLinesOnly = new HashSet<>(validationFile);
// Option 2 : unique lines and duplicate lines
Set<String> uniqueLines = new HashSet<>();
Set<String> duplicateLines = new HashSet<>();
for (String line : validationFile) {
if (!uniqueLines.add(line.toLowerCase())) {
duplicateLines.add(line.toLowerCase());
}
}
// Option 3 : unique lines and duplicate lines by Java Streams
Set<String> uniquesJava8 = new HashSet<>();
List<String> duplicatesJava8 = validationFile
.stream()
.filter(element -> !uniquesJava8.add(element.toLowerCase()))
.map(element -> element.toLowerCase())
.collect(Collectors.toList());
}
}
import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
import java.util.stream.Collectors;
public class ReadValidationFile {
public static void main(String[] args){
List<String> validationFile = new ArrayList<>();
try(BufferedReader br = new BufferedReader(new FileReader("validation_small.csv"));){
String line;
while((line = br.readLine())!= null){
validationFile.add(line);
}
} catch (FileNotFoundException e) {
//e.printStackTrace();
System.out.println("file not found " + e.getMessage());
} catch (IOException e) {
e.printStackTrace();
}
Set<String> uniques = new HashSet<>();
List<String> duplicates = validationFile.stream().filter(i->!uniques.add(i)).collect(Collectors.toList());
System.out.println(duplicates);
}
}
I try to get my code to work however when I run it there is nothing getting printed on my screen. I would like the user to enter a course code and then be presented with the name of the course. I want to use a HashMap to do this, however after some struggles thought id ask here for some suggestion.
import java.io.BufferedReader;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.util.HashMap;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.Scanner;
import java.util.Set;
import java.util.*;
import java.io.*;
public class reading_a_file {
static void pull_info(String courseCode) throws IOException{
BufferedReader read = new BufferedReader( new FileReader("CourseSample.txt"));
Map<String, String> course_info = new HashMap<String, String>();
String line;
String[] data;
while(((line = read.readLine()) != null))
{
line = read.readLine();
data = line.split(" ");
String courseID = data[0];
String courseName = data[1];
course_info.put(courseID, courseName);
if(courseCode==courseID){
System.out.println(course_info.get(courseName));
}
}
}
public static void main(String[] args) throws IOException{
Scanner console = new Scanner (System.in);
String course_code;
System.out.println("--------------------------------------------------");
System.out.println("Welcome to text file formatter by XM21");
System.out.println("--------------------------------------------------");
System.out.println("");
System.out.println("Please enter course id to see description (-1 to exit):");
System.out.println("CourseCode:");
course_code = console.nextLine();
pull_info(course_code);
}
}
and this is what my text file looks like :
sample of text file (just copy and paste to notepad) :
ITE221 Database Management System
ITE222 Web Development I Pre: ITE221 ITE232
ITE223 Cloud Technology Pre: ITE222
ITE224 Mobile Application Development I Pre: ITE 222
You cannot compare two String variables with == operator, you have to use equals().
And there are other different errors, like "line = read.readLine()" inside the while loop and the course_info.get(courseName) as you should use the key to get the value in your HashMap, and not the value to get the key.
Edit your block like this:
while ((line = read.readLine()) != null) {
// line = read.readLine(); // no need for this
data = line.split(" ");
String courseID = data[0];
String courseName = data[1];
course_info.put(courseID, courseName);
if (courseCode.equals(courseID)) { // correct comparation between String variables
System.out.println(course_info.get(courseID)); // the hashmap retreives the right value now
}
}
Edit
If you want to output all the strings after the Id you just have to add something really easy like
data = line.split(" ");
String courseID = data[0];
StringBuilder sb = new StringBuilder();
for (int i = 1; i < data.length; i++) {
sb.append(data[i]);
if (i < data.length - 1) {
sb.append(" ");
}
}
String courseName = sb.toString();
There are 3 major issues in your code.
1st issue:-
I see, you have put multiple readLine in your code
while(((line = read.readLine()) != null))
{
line = read.readLine(); // No need for this.
2nd issue:-
You should use String equal method
if(courseCode==courseID) // this is not good, as it's object comparsion.
Following code should be used. It will compare the string value.
if( courseCode.equals(courseID))
3rd issue:- You are not using right key for getting element from hashmap. Use CourseID
if (courseCode.equals(courseID)) {
System.out.println(course_info.get(courseID));
}
This is the complete program for you. This can be optimized further.
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
import java.util.Scanner;
public class reading_a_file {
static void pull_info(String courseCode) throws IOException {
BufferedReader read = new BufferedReader(new FileReader("CourseSample.txt"));
Map<String, String> course_info = new HashMap<String, String>();
String line;
String[] data;
while ((line = read.readLine()) != null) {
data = line.split(" ");
String courseID = data[0];
String courseName = data[1];
course_info.put(courseID, courseName);
if (courseCode.equals(courseID)) {
System.out.println(course_info.get(courseID));
}
}
}
public static void main(String[] args) throws IOException {
Scanner console = new Scanner(System.in);
String course_code;
System.out.println("--------------------------------------------------");
System.out.println("Welcome to text file formatter by XM21");
System.out.println("--------------------------------------------------");
System.out.println("");
System.out.println("Please enter course id to see description (-1 to exit):");
System.out.println("CourseCode:");
course_code = console.nextLine();
pull_info(course_code);
}
}
You have a few errors in this code that can cause this issue.
1) You're calling line = read.nextLine() twice in a row, so you're only looking at every second line.
2) Most of your course names have a space in them - meaning that even when you happen to land on the course you wanted during your search, you will only print out the first word of the course name.
3) Strings should be compared with equals, or equalsIngnoreCase - not the "==" sign which is for other comparisons.
4) Scanners are a resource - remember to close it!
5) when printing a value of the Map - use get(key) with the key, not the value.
You could improve the code by changing a few things:
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
import java.util.Scanner;
public class reading_a_file {
static void pull_info(String courseCode) throws IOException {
BufferedReader read = new BufferedReader(new FileReader("CourseSample.txt"));
Map<String, String> course_info = new HashMap<String, String>();
String line;
String[] data;
while ((line = read.readLine()) != null) {
data = line.split(" ");
String courseID = data[0];
String courseName = line.substring(line.indexOf(" ")+1);
course_info.put(courseID, courseName);
if (courseCode.equalsIgnoreCase(courseID)) {
System.out.println(courseName);
}
}
}
public static void main(String[] args) throws IOException {
Scanner console = new Scanner(System.in);
String course_code;
System.out.println("--------------------------------------------------");
System.out.println("Welcome to text file formatter by XM21");
System.out.println("--------------------------------------------------");
System.out.println();
System.out.println("Please enter course id to see description (-1 to exit):");
System.out.println("CourseCode:");
course_code = console.nextLine();
pull_info(course_code);
console.close();
}
}
Don't use the '==' operator for comparing String instances. This only checks if the two String instances share the same reference.
Replace '==' for the equals() method.
courseID.equals(courseCode)
Use "courseCode.equals(courseID)" instead of "courseCode==courseID". "==" compares references and it can be used for string literals, not for the strings created as "new String()", probably String.split() give you the array of strings created as "new String()" for each word. Be careful with the character casing also when putting it in a map.
Besides the already pointed out issues, you will most likely have to provide a full path to the file.
BufferedReader read = new BufferedReader( new FileReader("CourseSample.txt"));
To something like this
BufferedReader br = new BufferedReader(new FileReader("Drive/Folder/User/Desktop/file.txt"));
I have a txt file with the form:
Key:value
Key:value
Key:value
...
I want to put all the keys with their value in a hashMap that I've created. How do I get a FileReader(file) or Scanner(file) to know when to split up the keys and values at the colon (:) ? :-)
I've tried:
Scanner scanner = new scanner(file).useDelimiter(":");
HashMap<String, String> map = new Hashmap<>();
while(scanner.hasNext()){
map.put(scanner.next(), scanner.next());
}
Read your file line-by-line using a BufferedReader, and for each line perform a split on the first occurrence of : within the line (and if there is no : then we ignore that line).
Here is some example code - it avoids the use of Scanner (which has some subtle behaviors and imho is actually more trouble than its worth).
public static void main( String[] args ) throws IOException
{
String filePath = "test.txt";
HashMap<String, String> map = new HashMap<String, String>();
String line;
BufferedReader reader = new BufferedReader(new FileReader(filePath));
while ((line = reader.readLine()) != null)
{
String[] parts = line.split(":", 2);
if (parts.length >= 2)
{
String key = parts[0];
String value = parts[1];
map.put(key, value);
} else {
System.out.println("ignoring line: " + line);
}
}
for (String key : map.keySet())
{
System.out.println(key + ":" + map.get(key));
}
reader.close();
}
The below will work in java 8.
The .filter(s -> s.matches("^\\w+:\\w+$")) will mean it only attempts to work on line in the file which are two strings separated by :, obviously fidling with this regex will change what it will allow through.
The .collect(Collectors.toMap(k -> k.split(":")[0], v -> v.split(":")[1])) will work on any lines which match the previous filter, split them on : then use the first part of that split as the key in a map entry, then the second part of that split as the value in the map entry.
import java.io.IOException;
import java.nio.file.FileSystems;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.Map;
import java.util.stream.Collectors;
public class Foo {
public static void main(String[] args) throws IOException {
String filePath = "src/main/resources/somefile.txt";
Path path = FileSystems.getDefault().getPath(filePath);
Map<String, String> mapFromFile = Files.lines(path)
.filter(s -> s.matches("^\\w+:\\w+"))
.collect(Collectors.toMap(k -> k.split(":")[0], v -> v.split(":")[1]));
}
}
One more JDK 1.8 implementation.
I suggest using try-with-resources and forEach iterator with putIfAbsent() method to avoid java.lang.IllegalStateException: Duplicate key value if there are some duplicate values in the file.
FileToHashMap.java
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.Map;
import java.util.HashMap;
import java.util.stream.Stream;
public class FileToHashMap {
public static void main(String[] args) throws IOException {
String delimiter = ":";
Map<String, String> map = new HashMap<>();
try(Stream<String> lines = Files.lines(Paths.get("in.txt"))){
lines.filter(line -> line.contains(delimiter)).forEach(
line -> map.putIfAbsent(line.split(delimiter)[0], line.split(delimiter)[1])
);
}
System.out.println(map);
}
}
in.txt
Key1:value 1
Key1:duplicate key
Key2:value 2
Key3:value 3
The output is:
{Key1=value 1, Key2=value 2, Key3=value 3}
I would do it like this
Properties properties = new Properties();
properties.load(new FileInputStream(Path of the File));
for (Map.Entry<Object, Object> entry : properties.entrySet()) {
myMap.put((String) entry.getKey(), (String) entry.getValue());
}