You replace the data for a database record by using Cursor.putCurrent().

import com.sleepycat.db.Cursor;
import com.sleepycat.db.Database;
import com.sleepycat.db.DatabaseEntry;
import com.sleepycat.db.LockMode;
import com.sleepycat.db.OperationStatus; 

...
Cursor cursor = null;
Database myDatabase = null;
try {
    ...
    // Database open omitted for brevity
    ...
    // Create DatabaseEntry objects
    // searchKey is some String.
    DatabaseEntry theKey = new DatabaseEntry(searchKey.getBytes("UTF-8"));
    DatabaseEntry theData = new DatabaseEntry();

    // Open a cursor using a database handle
    cursor = myDatabase.openCursor(null, null);

    // Position the cursor. Ignoring the return value for clarity
    OperationStatus retVal = cursor.getSearchKey(theKey, theData, 
                                                 LockMode.DEFAULT);
    
    // Replacement data
    String replaceStr = "My replacement string";
    DatabaseEntry replacementData = 
        new DatabaseEntry(replaceStr.getBytes("UTF-8"));
    cursor.putCurrent(replacementData);
} catch (Exception e) {
    // Exception handling goes here
} finally {
   // Make sure to close the cursor
   cursor.close();
}

Note that you cannot change a record's key using this method; the key parameter is always ignored when you replace a record.

When replacing the data portion of a record, if you are replacing a record that is a member of a sorted duplicates set, then the replacement will be successful only if the new record sorts identically to the old record. This means that if you are replacing a record that is a member of a sorted duplicates set, and if you are using the default lexicographic sort, then the replacement will fail due to violating the sort order. However, if you provide a custom sort routine that, for example, sorts based on just a few bytes out of the data item, then potentially you can perform a direct replacement and still not violate the restrictions described here.

Under these circumstances, if you want to replace the data contained by a duplicate record, and you are not using a custom sort routine, then delete the record and create a new record with the desired key and data.