Java - Improper warning - Potential null pointer access

[ravindragullapalli]

In Java, Visual Studio Code is not recognizing "Objects.isNull" check statement while giving warning of Potential null pointer access (Java 536871364).

Environment

• Operating System: Kubuntu 22.04 (Linux x64 5.15.0-32-generic)
• JDK version: 1.8
• Visual Studio Code version: 1.78.2
• Java extension version: Language Support for java v1.18.0

Steps To Reproduce

For example, if the code is like

if (Objects.isNull(obj)){
System.out.println("obj is null");
return null;
}
return obj.toString();// Code is giving warning at this statment.

However, if I do this the warning disappears

if (obj == null){
System.out.println("obj is null");
return null;
}
return obj.toString();// No warning at this statement.

Current Result

"Potential null pointer access: The variable obj may be null at this locationJava(536871364)" warning is displayed

Expected Result

No warning should be there as null check is already done using Objects.isNull

Additional Informations

[snjeza]

@ravindragullapalli I can't reproduce the issue.
Could you attach a project example reproducing the error?

[ravindragullapalli]

@snjeza Please find the attached file. Hope this helps

JavaNullTest.zip

[ravindragullapalli]

Added another method nullTest3 where I am not getting that Potential Null Pointer Access. Please find attached zip file.

JavaNullTest.zip

[liuhaoXD]

Null check will also get misleading result in Assert.notNull scenary, here is an another example code snippet:

import javax.annotation.Nullable;

@Data
public class Request<T> {
    @Nullable
    private T data;
}

public class PageMonitorConfigController {
    @GetMapping("/xxx")
    public Object doSth (@RequestBody  Request<Sth> req) {
        Assert.notNull(pageableRequest.getData(), "data is null");
        // got 'Potential null pointer access' here ⬇️
        java.lang.System.out.println(pageableRequest.getData().getContent()); 
        return "done";
    }
}

AFAK, Intellj idea provides an annotation @Contract("null -> fail") for developer to tell static code analyzer annotated method will throw exception when given parameter is null

[iggycoder]

also with AssertJ:

@SuppressWarnings("unchecked")
ResponseEntity<Response> castedResult = (ResponseEntity<Response>)result.getResult();
assertThat(castedResult).isNotNull();
assertThat(castedResult.getStatusCode()).isEqualTo(HttpStatus.OK);

castedResult in second assertThat has warning Potential null pointer access: The variable castedResult may be null at this location

[mcavigelli]

This issue is marked with "upstream".

It seems @snjeza has fixed this issue in the eclipse.jdt.core project in the middle of December 2023, see mentioned issue.

What needs to be done to have this fix in the vscode-java extension?
It would be very useful to have it in our daily work.

[fbricon]

AFAICT it's already fixed in vscode-java, but the issue was not closed. I can't reproduce the issue with @ravindragullapalli's test project.
@mcavigelli are you still experiencing the problem? In which case you should definitely add a new sample project.

Else I'll close this issue.

[mcavigelli]

I can't reproduce it with the exact same code either. So, yes it's fixed and the issue can be closed.

[ravindragullapalli]

I can confirm that I am not getting this warning now. Thank you for fixing it.