checked-exceptions

If it possible to write byte code for a method that is supposed to throw a checked exception? For instance the following Java class doesn't compile unless the method declares it throws the checked exception: public class CheckedExceptionJava { public Class<?> testChecked(String s) throws ClassNotFoundException { return Class.forName(s); } } While the following Scala equivalent does ( because Scala doesn't have checked exceptions ) : class CheckedException { def testChecked( s : String ) = Class.forName( s ) } Even if the bytecode generated are almost identical: Compiled from

I have a method like this: public void getSomething(){ ... } I want to throw an Exception inside getSomething() . The compiler will not allow me to do that because my method doesn't allow Exception to be thrown in there. But I need to throw a subclass of Exception for my testing (I can't throw Unchecked Exception ) . This is clearly a hack but I need it for my testing. I tried EasyMock but it doesn't allow me to do that either. Any ideas how to do that? Thanks, Sean Nguyen Paul Bellora Method 1: This post by Alexey Ragozin describes how to use a generics trick to throw an undeclared checked

This question already has an answer here: Understanding checked vs unchecked exceptions in Java 21 answers I want to know how does one know to create and throw a checked exception or an unchecked exception. For example I have a service which takes some data and validates it before using it. During validation a certain field did not meet the rules and I want to throw an exception say ValidationException(). How will I know of decide it should be checked or unchecked. In another case I am calling an external web service from my code for example the google stock api. Let's assume i have a timeout

I was reading an article about checked and unchecked Exceptions in Java and found this article/link: https://projectlombok.org/disableCheckedExceptions.html According to the article it's just a hack developed for javac. Consider the code snippet below: import java.io.*; class Example { public static void main(String args[]) throws IOException { FileInputStream fis = null; fis = new FileInputStream("myfile.txt"); int k; while(( k = fis.read() ) != -1) { System.out.print((char)k); } fis.close(); } } Here I have to write public static void main(String args[]) throws IOException because I am

While creating custom exceptions, If we want to create a checked Exception we extend the Exception class and for unchecked exception we extend the RuntimeException class. My question is, how JVM handles subClasses of RuntimeException and Exception differently when they all are sub classes of the Exception class. It doesn't. The only difference is in requirements enforced by the compiler. You are mistaken that the JVM handles the exceptions differently, but your question is still valid if you are asking how the compiler treats them differently. And this has a simple answer: the rule does not

Why does it make sense to have Runtime Exceptions UnChecked (as opposed to if they were Checked )? If you didn't you would have to have try/catch blocks every time you accessed an array element, did a division operation and many other common scenarios. To put it another way, imagine this code: Map map = ... int i = ... (int[])map.get("foo")[3] = 2334 / i; would have to check for ClassCastException , ArrayIndexOutofBoundsException , ArithmeticException , UnsupportedOperationException and NullPointerException just off the top of my head. With Java the issue isn't unchecked exceptions. Checked

I noticed by accident that this throw statement (extracted from some more complex code) compiles: void foo() { try { } catch (Throwable t) { throw t; } } For a brief but happy moment I thought that checked exceptions had finally decided to just die already, but it still gets uppity at this: void foo() { try { } catch (Throwable t) { Throwable t1 = t; throw t1; } } The try block doesn't have to be empty; it seems it can have code so long as that code doesn't throw a checked exception. That seems reasonable, but my question is, what rule in the language specification describes this behavior? As