NullPointerException

[paulinasta]

Hi everyone,

As mentioned before, I’m a complete beginner, so any advice is greatly appreciated.

I wrote a simple rule:

package com.solibri.rule;
import java.text.MessageFormat;
import java.util.Collection;
import java.util.Collections;
import com.solibri.smc.api.checking.IntParameter;
import com.solibri.smc.api.checking.OneByOneRule;
import com.solibri.smc.api.checking.Result;
import com.solibri.smc.api.checking.ResultFactory;
import com.solibri.smc.api.checking.RuleParameters;
import com.solibri.smc.api.checking.StringParameter;
import com.solibri.smc.api.model.Component;
import com.solibri.smc.api.model.components.Space;
import com.solibri.smc.api.model.components.Window;

public class NumberOfWindowsInSpace2 extends OneByOneRule {
	
	private final RuleParameters params = RuleParameters.of(this);
	final IntParameter minimumAmountOfWindows = params.createInt("MinAmount");
	final StringParameter resultNameStringParameter = params.createString("ResultName");

	@Override
	public Collection<Result> check(Component component, ResultFactory resultFactory) {

		if (!(component instanceof Space)) {
			
			return null;
		}
		
		Space space = (Space) component;
		Collection<Window> windows = space.getWindows();
		int amountOfWindows = windows.size();

		int minimumAllowedAmount = minimumAmountOfWindows.getValue();

		if (amountOfWindows >= minimumAllowedAmount) {
			return Collections.emptyList();
		}

		String resultName = resultNameStringParameter.getValue();
		String resultDescription = MessageFormat
			.format("The amount of windows in space {0} is less than allowed.",
				component.getName());

		Result result = resultFactory.create(resultName, resultDescription);
		return Collections.singleton(result);
	}
}

But I keep getting the same error in Solibri:

Please send this error message and application information to [email protected] (see File->Help). 
Error Message: java.lang.NullPointerException: Cannot invoke "java.util.Collection.isEmpty()" because " " is null 
at com.solibri.smc.api.checking.OneByOneRule.a(Unknown Source) 
at java.basejava.lang.Iterable.forEach(Iterable.java:75) 
at com.solibri.smc.api.checking.OneByOneRule.check(Unknown Source)
at com.solibri.saf.plugins.checkingplugin.rule.RuleSerializedState.check(Unknown Source) 
at com.solibri.sae.greenox.Constraint.d(Unknown Source) 
at com.solibri.sae.greenox.Constraint.runCheck(Unknown Source) 
at com.solibri.saf.plugins.checkingplugin.ui.CheckingViewPanel$CheckTask.compute(Unknown Source) 
at com.solibri.saf.plugins.checkingplugin.ui.CheckingViewPanel$CheckTask.compute(Unknown Source) 
at java.base/java.util.concurrent.RecursiveTask.exec(RecursiveTask.java:95) 
at java.base/java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:290) 
at java.base/java.util.concurrent.ForkJoinPool$WorkQueue.topLevelExec(ForkJoinPool.java:1016) 
at java.base/java.util.concurrent.ForkJoinPool.scan(ForkJoinPool.java:1665) 
at java.base/java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1598) 
at java.base/java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:183)

After model checking. Could anyone explain what’s wrong with the code? Thanks!

[hlg]

@paulinasta said in NullPointerException:

   if (!(component instanceof Space)) {
  	return null;
  }

I guess this is making problems downstream.
You may want to return an empty list instead of null (like you do when amountOfWindows >= minimumAllowedAmount). The code that calls the OneByOneRule.check method tries to iterate over the result, with null that fails as you see.

[paulinasta]

@hlg thanks, did this before, but turns out the rules didn’t update in Solibri it was the problem indeed