Unable to retrieve the value from DB using Liferay Service Builder

I am learning Liferay and have been stuck in a place where I don't know what to do.

I will just brief out what I am doing.

Creating a Library Management System using service builder and have the following Code in Service.xml file.

<entity name="LMSBook" local-service="true" remote-service="false">
    <!-- PK fields -->
    <column name="bookId" type="long" primary="true" id-type="increment"/>
    <!-- UI fields -->
    <column name="bookTitle" type="String" />
    <column name="author" type="String" />
    <!-- Audit fields -->
    <column name="dateAdded" type="Date" />
</entity>

The Service build was successful without any errors. Now I am using following code to display the data from the table.

See the java below code:

List <LMSBook> books = LMSBookLocalServiceUtil.getLMSBooks(0, -1);
if(books.isEmpty()) {
    System.out.println("Empty");
} else {
    //Some Code Here
}

Here the books value is always null. I don't know why and DB has 3 rows in it but still its returning null. When I retrieve single value I am able to retrieve but when it come to multiple values it just returning NULL.

I am using following java code for single value retrieval:

LMSBook book = LMSBookLocalServiceUtil.getLMSBook(1);   

Please help me solve this problem.

There is an issue in your code part below:

List <LMSBook> books = LMSBookLocalServiceUtil.getLMSBooks(0, -1);

It says limit 0 to -1 which is not correct.

In order to get all records you should use below code:

List <LMSBook> books = LMSBookLocalServiceUtil.getLMSBooks(-1, -1);

If you use -1 as start and end, it will return all the records.