英文:
Getting variable name of the variable causing the error in try catch (Java)
问题
在Java中是否有可能返回变量名？
如果是这样的话，该如何实现？
（我正在使用IntelliJ Community Edition）
编辑：
下方的评论回答了错误所在的行。我从未意识到函数名所在的行实际上是针对 精确 行而不是函数的开头。
英文:
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.
答案1
得分: 1
假设有这段代码：
public class Test{
public static void main(String[] args){
try{
throw new IllegalArgumentException();
}catch(IllegalArgumentException iae){
iae.printStackTrace(); //获取堆栈轨迹
}
String s=null;
System.exit(s.length()); //Boom
}
}
如果你使用 java Test 运行它，会得到以下输出：
java.lang.IllegalArgumentException
at Test.main(Test.java:4) //这里是行号
Exception in thread "main" java.lang.NullPointerException
at Test.main(Test.java:9) //这里是行号
如果你使用 java -XX:++ShowCodeDetailsInExceptionMessages Test 运行它，会得到以下输出：
java.lang.IllegalArgumentException
at Test.main(Test.java:4)
Exception in thread "main" java.lang.NullPointerException: 无法调用 "String.length()"，因为 "<local1>" 为空
at Test.main(Test.java:9) //您可以得到行号和为空的内容，这里是一个没有名称的局部变量
如果你使用 javac -g Test.java 进行编译，然后运行它，你会得到更多的输出：
java.lang.IllegalArgumentException
at Test.main(Test.java:4)
Exception in thread "main" java.lang.NullPointerException: 无法调用 "String.length()"，因为 "s" 为空
at Test.main(Test.java:9)
这并不适用于其他异常，但 NPE（NullPointerException，空指针异常）经常会被抛出。
注意：-XX:+ShowCodeDetailsInExceptionMessages 只在 Java 14+ 版本中起作用！
英文:
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+!
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