Question

I have two HashMap, first one has 3149 records and the second one 5440 records, when I combine them, the result size is smaller then 3149+5440. Why and how can i solve it?

Map<String,String> bigMap = new HashMap<String, String>();
bigMap.putAll(hashMap1);
bigMap.putAll(hashMap2);

int j = 0;
for (Map.Entry<String, String> entry : bigMap.entrySet()) {
  System.out.println(j++);
}

I also cheched with this code to be sure if there is some common key.

for (Map.Entry<String, String> entry : readCsv(hashMap1).entrySet()) {
    String key = entry.getKey(); 
    String value = entry.getValue();  
    if(entry.getKey().equals(hashMap2).get(key))){
        System.out.println(i++);
    } 
}

Answer 1

Your hashMap1 and hashMap probably have a number of same keys. That’s why some entries are overridden by other entries with similar keys.