CODEWITHSUNDEEP
javamysqljakarta-eejdbcjdbctemplate
String
String

Reputation: 3728

JDBC ResultSet Data to HashMap

I am not able to set the data from ResultSet to HashMap.

My Query is returning 4 records, but HashMap is holding Last 2 records only. However, in the loop I am able to print 4 records data. Can any one help?

Here is my code:

workOrderMap=new HashMap<String, Integer>();

Statement statement = serviceconnection.createStatement();
ResultSet rs = statement.executeQuery("SELECT OPERATION,WORKORDERID FROM History WHERE OPERATION='CREATE'OR OPERATION='UPDATE'");
workOrderMap=new HashMap<String, Integer>();

while (rs.next()) {
    workOrderMap.put(rs.getString("OPERATION"), rs.getInt("WORKORDERID"));
    System.out.println(rs.getString("OPERATION")); // loops 4 times
}

System.out.println("List of Workorder id's" + workOrderMap.size()); // prints 2

Upvotes: 1

Views: 3343

Answers (2)

Bohemian
Bohemian

Reputation: 424983

There are only 2 distinct values returned from rs.getString("OPERATION").

This is hardly surprising, considering your WHERE clause only allows there to be 2 values:

WHERE OPERATION='CREATE' OR OPERATION='UPDATE'

In a Map, the keys are unique, so calling put() with the same key value will overwrite the value previously there.

When converting rowsets to a POJO, I prefer creating a List<Map<String, Object>> - each element of the list is a row, each entry in the associated Map are the column names and their values.

FYI, your WHERE clause can be written more elegantly as:

WHERE OPERATION IN ('CREATE', 'UPDATE')

Upvotes: 1

Sunil Rajashekar
Sunil Rajashekar

Reputation: 350

Since the keys are same, You will see only 2 values in hashmap.

Example

Map<String,Integer>  workOrderMap=new HashMap<String, Integer>();

workOrderMap.put("S", 1);
workOrderMap.put("S", 1);
workOrderMap.put("S2", 1);

System.out.println(workOrderMap.size());

OUTPUT : 2

Upvotes: 1

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