CODEWITHSUNDEEP
java
Arneev
Arneev

Reputation: 49

Getting variable name of the variable causing the error in try catch (Java)

Is it possible to return the variable name in java?

If so, how do you do it?

(I am using IntelliJ Community Edition)

EDIT:

Comment below answered about the line of where the error is. I never realize that the function name line was actually for the exact line and not for the start of the function.

Upvotes: 0

Views: 1478

Answers (1)

JCWasmx86
JCWasmx86

Reputation: 3583

Suppose this code:

public class Test{
    public static void main(String[] args){
        try{
            throw new IllegalArgumentException();
        }catch(IllegalArgumentException iae){
            iae.printStackTrace(); //Get stacktrace
        }
        String s=null;
        System.exit(s.length()); //Boom
    }
}

If you run it with java Test, you get this output:

java.lang.IllegalArgumentException
    at Test.main(Test.java:4) //Here, the line
Exception in thread "main" java.lang.NullPointerException
    at Test.main(Test.java:9) //Here, the line

If you run it with java -XX:++ShowCodeDetailsInExceptionMessages Test, you get this output:

java.lang.IllegalArgumentException
    at Test.main(Test.java:4)
Exception in thread "main" java.lang.NullPointerException: Cannot invoke "String.length()" because "<local1>" is null
    at Test.main(Test.java:9) //You get the line and what is null, here a local with no name

If you compile with javac -g Test.java, and run it, you even get more output:

java.lang.IllegalArgumentException
    at Test.main(Test.java:4)
Exception in thread "main" java.lang.NullPointerException: Cannot invoke "String.length()" because "s" is null
    at Test.main(Test.java:9)

It doesn't work for other exceptions, but a NPE is thrown quite often.

-XX:+ShowCodeDetailsInExceptionMessages will only work in Java 14+!

Upvotes: 1

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