How to stream a csv file with header to a HashMap<String, Double> in Java?

How to stream a csv file with header to a HashMap<String, Double> in Java?

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How to stream a csv file with header to a HashMap<String, Double> in Java?
Tag : java , By : Igor Carron
Date : November 28 2020, 04:01 AM

I wish did fix the issue. I'm not going to give you the entire solution but here is a way to approach this problem,
private void convertCsvtoMap(final String filePath) {
    try (Scanner in = new Scanner(new File(filePath))) {
        String line = null;
        Map<String, Double> resMap = new HashMap<>();
        while (in.hasNextLine()) {
            line = in.readLine();
            String[] fields = line.split(",");
            String key = fields[0].trim() + "|" + fields[1].trim() + ...;
            double value = Double.parseDouble(fields[5].trim());
            resMap.put(key, value);
    } catch (Exception ex) {
        /* Handle Exception */

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How to Convert Stream Stream<HashMap<String, Object>> to HashMap Array HashMap<String, Object>[]?

Tag : java , By : Saul
Date : March 29 2020, 07:55 AM
should help you out The following should work. Unfortunately, you have to suppress the unchecked warning.
HashMap<String, Object>[] arr = imagesStream.toArray(HashMap[]::new);
@SuppressWarnings({"unchecked", "rawtypes"})
HashMap<String, Object>[] array = stream.toArray(n -> new HashMap[n]);
@SuppressWarnings({"unchecked", "rawtypes"})
HashMap<String, Object>[] array = stream.toArray(new IntFunction<HashMap[]>() {
    public HashMap[] apply(int n) {
        return new HashMap[n];

Compare HashMap<String, Double> and List<ArrayList<String>> in Java

Tag : java , By : cautionsign
Date : March 29 2020, 07:55 AM
it should still fix some issue I have a HashMap like arr1[]-{AA=0.05, BB=0.031, CC=0.056} and List> like arr2[]-[ [AA,BB,CC] , [BB, CC] , [AA, CC]]. I want to take output like List>.It will be [ [0.05,0.031,0.056] , [0.031, 0.056] , [0.05, 0.056]]. I used , , Here you go:
Map<String, Double> mappings = //get mappings
List<ArrayList<String>> source = //get source
List<ArrayList<Double>> target = new ArrayList<>();
for(ArrayList<String> sourceElement : source){
    ArrayList<Double> targetElememt = new ArrayList<>();
    for(String sourceElementString : sourceElement){

Replace String With hashmap value using java 8 stream

Tag : java , By : Hans-Inge
Date : March 29 2020, 07:55 AM
seems to work fine As this cannot be made using only forEach() (message must be effectively final), workaround could be to create a final container (e. g. List) which stores a single String that is re-written:
final List<String> msg = Arrays.asList("helloABC");
map.forEach((key, value) -> msg.set(0, msg.get(0).replace(key, value)));
String test = msg.get(0);
String test = map.entrySet()
                         (s, e) -> s.replace(e.getKey(), e.getValue()), 
                         (s1, s2) -> null);

Set of String with Stream to HashMap in Java 8

Tag : java , By : Sebastian Gift
Date : March 29 2020, 07:55 AM
To fix this issue You don't need the map() step. The logic that produces a List from a String should be passed to Collectors.toMap():
Map<String, List<String>> map = 
                                   string -> {
                                       // put logic that returns List<String> here

Java 8 stream HashMap<String, ArrayList<String>> to SortedMap<String, Integer>

Tag : java , By : Mahyar Sepehr
Date : March 29 2020, 07:55 AM
may help you . I have HashMap> professions, and I want to create a SortedMap where the first entry is a string same to the first entry of the hashmap, and second entry is an Integer equal to the size of the ArrayList in the first map corresponding to the string. I also want that the sortedMap is sorted by the first entry (the string). , You're looking for the toMap collector as opposed to the groupingBy:
Map<String, Integer> resultSet = 
                        e -> e.getValue().size(),
                        (left, right) -> left, TreeMap::new));
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