CODEWITHSUNDEEP
javaexcelapache-poi
Kaustubh
Kaustubh

Reputation: 506

Map values are getting overridden while iterating through Map

I'm trying to fetch data from excel sheet using Apache poi jars. I have three rows and four columns in my excel. The actual data is in 2nd and 3rd row. 1st row is headers which I'm using as key for fetching the values. While I do this, the output I get always shows the 3rd row data. I have tried debugging it and observed that 2nd row data is getting overridden by 3rd row.

Here is my code snippet

public static void main(String[] args) throws IOException {

    loadExcel();
    
    Map<String, Map<String, String>> superMap = new HashMap<String, Map<String,String>>();
    
    Map<String, String> hm = new HashMap<>();

    for (int i = 1; i < excelSheet.getLastRowNum() + 1; i++) {

        int lastColnum = excelSheet.getRow(0).getLastCellNum();
        for (int j = 0; j < lastColnum; j++) {
            System.out.println("reading excel column");
            String key = excelSheet.getRow(0).getCell(j).getStringCellValue();
            String value = excelSheet.getRow(i).getCell(j).getStringCellValue();
            hm.put(key, value);
        }
        superMap.put("MASTERDATA", hm);
    }

    for (Entry<String, Map<String, String>> set : superMap.entrySet()) {
        System.out.println(set.getKey() + " : " + set.getValue());
    }
}

Output:

MASTERDATA : {Blood Group=test2bg, UserName=test2, Address=test2add, Password=test2pass}

My Data in excel:

Username | Password  | Address | Blood Group
test1    | test1pass |test1add |  test1bg
test2    | test2passs|test2add |  test2bg

I have tried putting the map into a superMap, but still no luck. Any suggestions / advise would help. Thanks in advance.

Upvotes: 2

Views: 945

Answers (3)

Eklavya
Eklavya

Reputation: 18430

You are putting every row data in the same key in the map. In HashMap single key has one value. So every time it replaces the previous value of MASTERDATA key.

superMap.put("MASTERDATA", hm);

Maybe you need to use List<Map<String, String>> instead of Map<String, Map<String, String>> to store all row data as list. And also need to create map inside in the loop for not using same map reference again.

List<Map<String, String>> list = new ArrayList<>();
for (int i = 1; i < excelSheet.getLastRowNum() + 1; i++) {
    Map<String, String> hm = new HashMap<>();
    int lastColnum = excelSheet.getRow(0).getLastCellNum();
    for (int j = 0; j < lastColnum; j++) {
        System.out.println("reading excel column");
        String key = excelSheet.getRow(0).getCell(j).getStringCellValue();
        String value = excelSheet.getRow(i).getCell(j).getStringCellValue();
        hm.put(key, value);
    }
    list.add(hm);
}

Upvotes: 2

Eritrean
Eritrean

Reputation: 16498

The issue is at this line, where you put the same key for each row

superMap.put("MASTERDATA", hm);

you could use the row number, i.e your i var of the outer loop to make it variable and unique

EDIT

Map<String, Map<String, String>> superMap = new HashMap<String, Map<String,String>>();

for (int i = 1; i < excelSheet.getLastRowNum() + 1; i++) {
    
    Map<String, String> hm = new HashMap<>();

    int lastColnum = excelSheet.getRow(0).getLastCellNum();
    for (int j = 0; j < lastColnum; j++) {
        System.out.println("reading excel column");
        String key = excelSheet.getRow(0).getCell(j).getStringCellValue();
        String value = excelSheet.getRow(i).getCell(j).getStringCellValue();
        hm.put(key, value);
    }
    superMap.put("MASTERDATA_" + i, hm);
}

to get something like

MASTERDATA_1 : {Blood Group=test1bg, UserName=test1, Address=test1add, Password=test1pass}
MASTERDATA_2 : {Blood Group=test2bg, UserName=test2, Address=test2add, Password=test2pass}

Upvotes: 3

Tymur Dadsahov
Tymur Dadsahov

Reputation: 83

You can not use the same key twice, because value will be overwritten, but you can put map in your superMap after the loop. In that case you will have "masterdata" key and map with multiple pairs as a value

Upvotes: 0

Related Questions