My json file looks like this [actually it has more, I am just putting 2 blocks for example]
[{
"answerValue": "2021-02-01",
"parentId": "Policy",
"instance": 1,
"fieldId": "PolicyEffectiveDate"
},
{
"answerValue": "2012",
"parentId": "Insured",
"instance": 1,
"fieldId": "DateBusinessStarted"
}
]
I want to store them in a HashMap and print them.
public void MapCheck() {
Map<String, Object> dataMap = new HashMap<>();
List<Map> lstMap = new ArrayList<>();
dataMap.put("answerValue:", "2021-02-01");
dataMap.put("parentId:", "Policy");
dataMap.put("instance:", 1);
dataMap.put("fieldId:", "PolicyEffectiveDate");
lstMap.add(dataMap);
dataMap.put("answerValue:", "Assurestart LLC");
dataMap.put("parentId:", "Insured");
dataMap.put("instance:", 1);
dataMap.put("fieldId:", "Business_Name");
lstMap.add(dataMap);
System.out.println(lstMap);
}
public static void main(String[] args) {
Test t = new Test();
t.MapCheck();
}
}
Expected: I wanted it to print
[{parentId:=Policy, fieldId:=PolicyEffectiveDate, answerValue:=2021-02-01, instance:=1}, {parentId:=Insured, fieldId:=Business_Name, answerValue:=Assurestart LLC, instance:=1}]
Actual: It is printing, the last value twice.
[{parentId:=Insured, fieldId:=Business_Name, answerValue:=Assurestart LLC, instance:=1}, {parentId:=Insured, fieldId:=Business_Name, answerValue:=Assurestart LLC, instance:=1}]
How can I make it print 2 different values? Thanks in advance for your time and ideas.
You should create a new map for the second entry instead of overwriting the first entry's values. Add
dataMap = new HashMap<>();
After adding the first entry to the list.
You should create a new map for the second map in the list:
Map<String, Object> dataMap = new HashMap<>();
List<Map<String, Object>> lstMap = new ArrayList<>();
dataMap.put("answerValue:", "2021-02-01");
dataMap.put("parentId:", "Policy");
dataMap.put("instance:", 1);
dataMap.put("fieldId:", "PolicyEffectiveDate");
lstMap.add(dataMap);
dataMap = new HashMap<>(); // create a new map!
dataMap.put("answerValue:", "Assurestart LLC");
dataMap.put("parentId:", "Insured");
dataMap.put("instance:", 1);
dataMap.put("fieldId:", "Business_Name");
lstMap.add(dataMap);
That said, if you actually want to generate JSON, or read a JSON file, I recommend using a JSON serialisation/deserialisation library, such as GSON . That way, you can represent your data not as hash maps, but a class like this:
class MyObject {
private String answerValue;
private String parentId;
private int instance;
private String fieldId;
// getters & setters...
}
HashMap as you know is a data structure that works based on unique key and value pair property. In the example above when you perform dataMap.put("answerValue:", "2021-02-01"); it saves the value for this key in the HashMap. However when you perform, dataMap.put("answerValue:", "Assurestart LLC"); the second time, it will override the value of "answerValue:" key as it already exists there.
A better approach is to create a new class that can contain all this data in it and then you can decide on a unique key to store this data in. Thus your values will be an object that contains this entire block of data. For example,
public class MyData {
private String answerValue;
private String parentId;
private Integer instance;
private String fieldId;
//Setters and getters
...
}
The technical post webpages of this site follow the CC BY-SA 4.0 protocol. If you need to reprint, please indicate the site URL or the original address.Any question please contact:yoyou2525@163.com.