javax.inject @Inject not working as expected

Question

I am trying to understand how javax.inject gonna work, but it seems not working as expected.

package demo333;

import javax.inject.Inject;
import javax.inject.Named;

public class Demo2452 {

    @Inject private @Named("AA1") AA aa;

    public static void main(String[] args) {
        new Demo2452().m2();
    }

    private void m2() {
        System.out.println(aa.hello());
    }

}


interface AA{
    String hello();
}

@Named("AA1")
class AA1 implements AA{

    @Override
    public String hello() {
        return "helllllooooo";
    }

}

I am getting NullPointerException as below stacktrace:

Exception in thread "main" java.lang.NullPointerException at demo333.Demo2452.m2(Demo2452.java:15) at demo333.Demo2452.main(Demo2452.java:11)

Could anyone please tell me what went wrong in above code?

You must not call `new` yourself for objects for which injection should happen. For spring create a context, and ask it for an instance of this object class. — Thorbjørn Ravn Andersen, Oct 13 '19 at 16:38
@ThorbjørnRavnAndersen i didnt used new , please check my code — john, Oct 13 '19 at 16:55
Possible duplicate of [What is a NullPointerException, and how do I fix it?](https://stackoverflow.com/questions/218384/what-is-a-nullpointerexception-and-how-do-i-fix-it) — gnat, Oct 13 '19 at 18:12

score 1 · Accepted Answer · edited Oct 13 '19 at 21:03

1

You need to add @Component on the class .

@Component
Class Example{}

edited Oct 13 '19 at 21:03

pvpkiran

25,582
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answered Oct 13 '19 at 18:12

shubhendra sen

176
11

iam not using spring – john Oct 13 '19 at 18:13
1

As far as my knowledge goes your application must use any framework or cdi to use @inject – shubhendra sen Oct 13 '19 at 18:23
hey i had another issue, could you please check here: https://stackoverflow.com/questions/58367436/javax-inject-issue-getting-null – john Oct 13 '19 at 20:12

javax.inject @Inject not working as expected

1 Answers1