Cleaned code and added comments

components/device-mgt/org.wso2.carbon.device.mgt.common/src/main/java/org/wso2/carbon/device/mgt/common/EnrolmentInfo.java

@@ -96,19 +96,14 @@ public class EnrolmentInfo {
     public boolean equals(Object obj) {
         if (obj instanceof EnrolmentInfo) {
             EnrolmentInfo tempInfo = (EnrolmentInfo) obj;
-            if (owner != null && ownership != null
+            if (owner != null && ownership != null) {
-                && tempInfo.getOwner() != null && tempInfo.getOwnership() != null) {
+                if (tempInfo.getOwner() != null && tempInfo.getOwnership() != null) {
-
                     if (owner.equals(tempInfo.getOwner()) && ownership.equals(tempInfo.getOwnership())) {
                         return true;
-                } else {
-                    return false;
                     }
-            } else {
-                return false;
                 }
-        } else {
-            return false;
             }
         }
+        return false;
+    }
 }

components/device-mgt/org.wso2.carbon.device.mgt.core/src/main/java/org/wso2/carbon/device/mgt/core/dao/DeviceDAO.java

@@ -31,38 +31,160 @@ import java.util.List;
  */
 public interface DeviceDAO {
 
+    /**
+     * This method is used to add a device.
+     *
+     * @param typeId device type id.
+     * @param device device object.
+     * @param tenantId tenant id.
+     * @return returns the id of the persisted device record.
+     * @throws DeviceManagementDAOException
+     */
     int addDevice(int typeId, Device device, int tenantId) throws DeviceManagementDAOException;
 
+    /**
+     * This method is used to update a given device.
+     *
+     * @param typeId device type id.
+     * @param device device object.
+     * @param tenantId tenant id.
+     * @return returns the id of updated device.
+     * @throws DeviceManagementDAOException
+     */
     int updateDevice(int typeId, Device device, int tenantId) throws DeviceManagementDAOException;
 
+    /**
+     * This method is used to remove a device.
+     *
+     * @param deviceId id of the device that should be removed.
+     * @param tenantId tenant id.
+     * @return returns the id of removed device.
+     * @throws DeviceManagementDAOException
+     */
     int removeDevice(DeviceIdentifier deviceId, int tenantId) throws DeviceManagementDAOException;
 
+    /**
+     * This method is used to retrieve a device of a given id.
+     *
+     * @param deviceId device id.
+     * @param tenantId tenant id.
+     * @return returns the device object.
+     * @throws DeviceManagementDAOException
+     */
     Device getDevice(DeviceIdentifier deviceId, int tenantId) throws DeviceManagementDAOException;
 
+    /**
+     * This method is used to retrieve all the devices of a given tenant.
+     *
+     * @param tenantId tenant id.
+     * @return returns a list of devices.
+     * @throws DeviceManagementDAOException
+     */
     List<Device> getDevices(int tenantId) throws DeviceManagementDAOException;
 
+    /**
+     * This method is used to retrieve all the devices of a given tenant and device type.
+     *
+     * @param type device type.
+     * @param tenantId tenant id.
+     * @return returns list of devices.
+     * @throws DeviceManagementDAOException
+     */
     List<Device> getDevices(String type, int tenantId) throws DeviceManagementDAOException;
 
+    /**
+     * This method is used to retrieve devices of a given user.
+     * @param username user name.
+     * @param tenantId tenant id.
+     * @return returns list of devices.
+     * @throws DeviceManagementDAOException
+     */
     List<Device> getDevicesOfUser(String username, int tenantId) throws DeviceManagementDAOException;
 
+    /**
+     * This method is used to retrieve the device count of a given tenant.
+     *
+     * @param tenantId tenant id.
+     * @return returns the device count.
+     * @throws DeviceManagementDAOException
+     */
     int getDeviceCount(int tenantId) throws DeviceManagementDAOException;
 
+    /**
+     * This method is used to retrieve devices of a given device name.
+     * @param deviceName device name.
+     * @param tenantId tenant id.
+     * @return returns list of devices.
+     * @throws DeviceManagementDAOException
+     */
     List<Device> getDevicesByName(String deviceName, int tenantId) throws DeviceManagementDAOException;
 
+    /**
+     * This method is used to add an enrollment information of a given device.
+     *
+     * @param device device object.
+     * @param tenantId tenant id.
+     * @return returns the id of the enrollment.
+     * @throws DeviceManagementDAOException
+     */
     int addEnrollment(Device device, int tenantId) throws DeviceManagementDAOException;
 
+    /**
+     * This method is used to set the current enrollment status of given device and user.
+     *
+     * @param deviceId device id.
+     * @param currentOwner current user name.
+     * @param status device status.
+     * @param tenantId tenant id.
+     * @return returns true if success.
+     * @throws DeviceManagementDAOException
+     */
     boolean setEnrolmentStatus(DeviceIdentifier deviceId, String currentOwner, Status status,
                       int tenantId) throws DeviceManagementDAOException;
 
+    /**
+     * This method is used to get the status of current enrollment of a given user and device.
+     *
+     * @param deviceId device id.
+     * @param currentOwner device owner.
+     * @param tenantId tenant id.
+     * @return returns current enrollment status.
+     * @throws DeviceManagementDAOException
+     */
     Status getEnrolmentStatus(DeviceIdentifier deviceId, String currentOwner,
                               int tenantId) throws DeviceManagementDAOException;
 
+    /**
+     * This method is used to retrieve current enrollment of a given device and user.
+     *
+     * @param deviceId device id.
+     * @param currentUser user name.
+     * @param tenantId tenant id.
+     * @return returns EnrolmentInfo object.
+     * @throws DeviceManagementDAOException
+     */
     EnrolmentInfo getEnrolment(DeviceIdentifier deviceId, String currentUser,
                                int tenantId) throws DeviceManagementDAOException;
 
-
+    /**
+     * This method is used to retrieve devices of a given enrollment status.
+     *
+     * @param status enrollment status.
+     * @param tenantId tenant id.
+     * @return returns list of devices.
+     * @throws DeviceManagementDAOException
+     */
     List<Device> getDevicesByStatus(EnrolmentInfo.Status status, int tenantId) throws DeviceManagementDAOException;
 
+    /**
+     * This method is used to retrieve the enrollment id of a given device and status.
+     *
+     * @param deviceId device id.
+     * @param status enrollment status.
+     * @param tenantId tenant id.
+     * @return returns the id of current enrollment.
+     * @throws DeviceManagementDAOException
+     */
     int getEnrolmentByStatus(DeviceIdentifier deviceId, Status status,
                                     int tenantId) throws DeviceManagementDAOException;
 }

components/device-mgt/org.wso2.carbon.device.mgt.core/src/main/java/org/wso2/carbon/device/mgt/core/operation/mgt/dao/impl/CommandOperationDAOImpl.java

@@ -120,9 +120,11 @@ public class CommandOperationDAOImpl extends OperationDAOImpl {
         List<CommandOperation> commandOperations = new ArrayList<>();
         try {
             Connection conn = OperationManagementDAOFactory.getConnection();
-            String sql = "SELECT o.ID, co1.ENABLED, co1.STATUS, o.TYPE, o.CREATED_TIMESTAMP, o.RECEIVED_TIMESTAMP, o.OPERATION_CODE FROM (SELECT co.OPERATION_ID, co.ENABLED, dm.STATUS FROM DM_COMMAND_OPERATION co " +
+            String sql = "SELECT o.ID, co1.ENABLED, co1.STATUS, o.TYPE, o.CREATED_TIMESTAMP, o.RECEIVED_TIMESTAMP, " +
-                    "INNER JOIN (SELECT ENROLMENT_ID, OPERATION_ID, STATUS FROM DM_ENROLMENT_OPERATION_MAPPING WHERE ENROLMENT_ID = ? " +
+                    "o.OPERATION_CODE FROM (SELECT co.OPERATION_ID, co.ENABLED, dm.STATUS " +
-                    "AND STATUS = ?) dm ON dm.OPERATION_ID = co.OPERATION_ID) co1 INNER JOIN DM_OPERATION o ON co1.OPERATION_ID = o.ID";
+                    "FROM DM_COMMAND_OPERATION co INNER JOIN (SELECT ENROLMENT_ID, OPERATION_ID, STATUS " +
+                    "FROM DM_ENROLMENT_OPERATION_MAPPING WHERE ENROLMENT_ID = ? AND STATUS = ?) dm " +
+                    "ON dm.OPERATION_ID = co.OPERATION_ID) co1 INNER JOIN DM_OPERATION o ON co1.OPERATION_ID = o.ID";
 
             stmt = conn.prepareStatement(sql);
             stmt.setInt(1, enrolmentId);