列表<hashmap> list = new ArrayList<>(); java</hashmap>

Question

In java, Is this wrong? Whenever I tried to add something my old value is replaced with new value. Is it not possible to store data in list of hashmap like below statement? When I store data as string List list = new ArrayList<>(); like this.. it is working properly but when I tried to write hashmap in generic it is not returning old data.. I need your advice.

List<HashMap> dataArrayList = new ArrayList<>();
LinkedHashMap<String, String> hashMap = new LinkedHashMap<>();
for (int j = 0; j < name.length; j++) {
    System.out.print("Enter " + name[j] + ":");
    storedata[j] = scanner.next();
    hashMap.put(name[j], storedata[j]);
}

dataArrayList.add(hashMap);

Answer 1

Based on the code snippet provided the values in hashMap will only get updated in case there are duplicates in your name array. I am not getting why you are creating a List of hashmap as you are only adding one hashmap in the list.

I think what you are trying to say is as below name array ={tom, jerry, tom, jerry, duck} storedata array ={d1, d2, d3, d4, d5}

output: {[tom,{d1,d3}],[jerry,{d2,d4}],[duck,{d5}]}

So if you want something like this then create a HashMap as below

LinkedHashMap<String,List<String>> hashMap=new LinkedHashMap<>();
for (int j = 0; j < name.length; j++) {
    System.out.print("Enter " + name[j] + ":");
    storedata[j] = scanner.next();
    if(!hashMap.containsKey(name[j])
       hashMap.put(name[j],new ArrayList<>());
    hashMap.put(name[j],storedata[j]);
}
System.out.println(hashMap);