heap

public class CustomResultHandler implements ResultHandler {

    private ArrayList<HashMap<String,String>> recordList;
    private CallbackInterface callbackClass;
    private int MAX_COUNT= 100;

    public CustomResultHandler() {
        super();
        this.recordList = new ArrayList<HashMap<String,String>>();
    }

    @Override
    public void handleResult(ResultContext resultContext) {

        recordList.add((HashMap<String, String>) resultContext.getResultObject());

        if(recordList.size() == MAX_COUNT) {
            System.out.println("Invoking Callback method");
            callbackClass.processData(recordList);
            recordList.clear();
        }


    }

    public ArrayList<HashMap<String,String>> getRecordList() {
        return recordList;
    }

    public void setRecordList(ArrayList<HashMap<String,String>> recordList) {
        this.recordList = recordList;
    }

    public Object getCallbackClass() {
        return callbackClass;
    }

    public void setCallbackClass(CallbackInterface callbackClass) {
        this.callbackClass = callbackClass;
    }


}

public interface CallbackInterface {

    public void processData(ArrayList<HashMap<String,String>> recordList);

}

public class CallbackImpl implements CallbackInterface {

    @Override
    public void processData(ArrayList<HashMap<String, String>> recordList) {
        System.out.println("Callback operation invoked for list size: " + recordList.size());

    }

}

public ArrayList<HashMap<String, String>> getAllUsers(CustomResultHandler objCustomResultHandler) {
        //set the custom result handler in sql session
        sqlSession.select("com.memoryleak.poc.persistence.UserMapper.getAllUsers", objCustomResultHandler);

        return userMapper.getAllUsers(objCustomResultHandler);
}

public static void main(String[] args) {

        ApplicationContext context = new ClassPathXmlApplicationContext("Beans.xml");

        UserService userService = (UserService) context.getBean("userService");

        CustomResultHandler objResultHandler = new CustomResultHandler();
        CallbackInterface objCallback = new CallbackImpl();
        objResultHandler.setCallbackClass(objCallback);

        System.out.println("Users List: " + userService.getAllUsers(objResultHandler));



}