Convert CSV values to a HashMap key value pairs in JAVA

Question

HI I have a csv called test.csv . I am trying to read the csv line by line and convert the values into a hash key value pairs . Here is the code :-

Answer 1

Using FasterXML's CSV package: https://github.com/FasterXML/jackson-dataformats-text/tree/master/csv

public static List<Map<String, String>> read(File file) throws JsonProcessingException, IOException {
    List<Map<String, String>> response = new LinkedList<Map<String, String>>();
    CsvMapper mapper = new CsvMapper();
    CsvSchema schema = CsvSchema.emptySchema().withHeader();
    MappingIterator<Map<String, String>> iterator = mapper.reader(Map.class)
            .with(schema)
            .readValues(file);
    while (iterator.hasNext()) {
        response.add(iterator.next());
    }
    return response;
}

Answer 2

The problem is that when you split your str, the first element in each line is alone (i.e 1 and 2). So arr only contains ["1"], and hence arr[1] doesn't exists.

I.e for the example input :

1,"testCaseName":"ACLTest"

split by , => str contains {1, testCaseName:ACLTest}
split by : at the first iteration => arr contains {1}

Example :

String s = "1,testCaseName:ACLTest";
String str[] = s.split(",");
System.out.println(Arrays.toString(str));
for(String p : str){
    String arr[] = p.split(":");
    System.out.println(Arrays.toString(arr));
}

Output :

[1, testCaseName:ACLTest]
[1] //<- here arr[1] doesn't exists, you only have arr[0] and hence the ArrayIndexOutOfBoundsException when trying to access arr[1]
[testCaseName, ACLTest]

---

To fix your code (if you don't want to use a CSV parser), make your loop starting at 1 :

for(int i=1;i<str.length;i++){
      String arr[] = str[i].split(":");
      map.put(arr[0], arr[1]);
}

---

Another problem is that the HashMap use the hashCode of the keys to store the (key, value) pairs.

So when insering "testCaseName":"ACLTest" and "testCaseName":"DCLAddTest", the first value will be erased and replace by the second one :

Map<String, String> map = new HashMap<>();
map.put("testCaseName","ACLTest");
map.put("testCaseName","DCLAddTest");
System.out.println(map);

Output :

{testCaseName=DCLAddTest}

So you have to fix that too.