Spring jdbcTemplate NPE exception [duplicate] - spring

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Why is my Spring #Autowired field null?
(21 answers)
Closed 2 years ago.
I am trying to use the jdbcTemplate to query a MySQL database to get the SYSDATE. So the query is as simple as SELECT SYSDATE()
However, I get the following error:
Exception in thread "main" java.lang.NullPointerException
at com.trade.xml.modifier.Test.<init>(Test.java:18)
at com.trade.xml.modifier.TradeModifierApplication.main(TradeModifierApplication.java:17)
Here is a bit of what I do:
I created a DatabaseConfiguration.class which should take all the connection details from the application.properties
The application.properties looks like this:
spring.datasource.url=jdbc:mysql://localhost:3306/xmlconverter
spring.datasource.username=root
spring.datasource.password=
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
spring.jpa.properties.hibernate.dialect=org.hibernate.dialect.MariaDBDialect
The DatabaseConfiguration.class looks like this
#Configuration
public class DatabaseConfiguration {
#Value("${spring.datasource.driver-class-name}")
private String driverName;
#Value("${spring.datasource.url}")
private String url;
#Value("${spring.datasource.username}")
private String userName;
#Value("${spring.datasource.password}")
private String password;
#Bean(name = "dataSource")
public DataSource dataSource() {
final DriverManagerDataSource dataSource = new DriverManagerDataSource();
dataSource.setDriverClassName(driverName);
dataSource.setUrl(url);
dataSource.setUsername(userName);
dataSource.setPassword(password);
return dataSource;
}
#Bean
public JdbcTemplate dbjdbcTemplate() {
return new JdbcTemplate(dataSource());
}
}
2.I also created a Test.class where I wrote my method for querying
#Service
public class Test {
//Since a bean is created in DatabaseConfiguration,
//"template = new JdbcTemplate()" is omitted (should be recognized automatically, right?)
#Autowired
private JdbcTemplate template;
public String getDate() {
String sql = "SELECT SYSDATE()";
return template.queryForObject(sql, String.class);
}
}
The main class looks as follows
#SpringBootApplication
public class TradeModifierApplication {
public static void main(String[] args) {
SpringApplication.run(TradeModifierApplication.class, args);
Test test = new Test();
System.out.println(test.getDate());
At this point I have read the whole Internet and I am not sure what is the root cause of this NPE. Any help/hints will be appreciated.

Answer 1

The problem should be this line in TradeModifierApplication:
Test test = new Test();
You should let the spring container to instance Test class.
One way would be to inject by:
public static void main(String[] args) {
ApplicationContext applicationContext = SpringApplication.run(TradeModifierApplication.class, args);
Test service = applicationContext.getBean(Test.class);
service.getDate());
}
}