JDBCTemplate giving Null Pointer Exception?

Question

I'm trying to insert some values into my table and I keep getting a null pointer exception. I first thought it was because some values were null, but even with the ones which are never null give me NPE.

Here's my TwitterJDBCTemplate:

@Service
public class TwitterJDBCTemplate {


@Autowired
private DataSource dataSource;
private JdbcTemplate jdbcTemplateObject;




public void storeTweet(long id, long user_id, String created_at, String language, String message, String searchterm,
        String user_description, String user_location, String user_pic, String user_screenname, String username) {

    String SQL = "insert into tweets (id, user_id, created_at, language,"
            + "message, searchterm, user_description, user_location, user_pic,"
            + "user_screenname, username) values (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)";

    jdbcTemplateObject.update(SQL, new Object[] { id, user_id, created_at, language, message, searchterm,
            user_description, user_location, user_pic, user_screenname, username });
}

Here's my Main App:

@SpringBootApplication
@EnableScheduling
public class TwitterApp {

public static void main(String[] args) {

    // TODO Auto-generated method stub
    SpringApplication.run(TwitterApp.class, args);

}
}

My application.properties file:

server.port: 9040
management.port: 9041
management.address: 127.0.0.1

spring.datasource.url=jdbc:mysql://localhost:3306/twitter

spring.datasource.username=root
spring.datasource.password=********

spring.datasource.driver-class-name=com.mysql.jdbc.Driver

spring.jpa.database-platform=org.hibernate.dialect.PostgreSQLDialect 

spring.jpa.show-sql=false

spring.jpa.hibernate.ddl-auto=create

Inside of my TweetController:

@RestController
@Scope("singleton")
public class TweetController {


@Autowired
TwitterJDBCTemplate template;

Answer 1

You did not create jdbcTemplate object at your app,that's why you are getting NPE. I think there is two posible options:

1) Add jdbcTemplate bean to spring context and autowire it.

@Bean
public JdbcTemplate getJdbcTemplate() {
   return new JdbcTemplate(dataSource());
}

And your class

@Service
public class TwitterJDBCTemplate {


@Autowired
private JdbcTemplate jdbcTemplateObject;
.....
}

2) Create jdbcTemplate inside your class

JdbcTemplate jdbcTemplate = new JdbcTemplate(dataSource);

In addition i bielive that it's not the best practice to use methods with big number of params. Maybe you should create your custom class Twit or smth like this.

Answer 2

Of course you have to create a JdbcTemplate bean in your application context before you @autowire it in your code.

You can do it for example in a @Configuration class.

  @Configuration
  public class DatabaseConfiguration {

           @Bean
           @Primary
           @ConfigurationProperties(prefix = "spring.datasource")
           public javax.sql.DataSource primaryDataSource() {
                   return DataSourceBuilder.create().build();
           }

           @Bean
           public JdbcTemplate getJdbcTemplate() {
                   return new JdbcTemplate(primaryDataSource());
           }

  }

According to this tutorial. Adding this dependency will take care of creating the JdbcTemplate for the application.

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-jdbc</artifactId>
        </dependency>

Then you can @autowire as follows,

@Autowired
private JdbcTemplate jdbcTemplate