What are generic exceptions in Java?

It refers to exception class that is near the top of the exception class hierarchy. Note that an exception class cannot be a generic class in the Java sense of generic types. The JLS says: “Note that a subclass of Throwable cannot be generic (§8.1.2).” –

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Can we create generic exception in Java?

In order to make the generic type on the exception class useful it should be possible to create different catch blocks for different generic types. This however, is not possible because of type erasure. At runtime all the generic type information will be lost and MyException will just be MyException.

Can exception types be made generic?

Since type parameters of generics are erased at runtime, there is no way to distinguish between generic exceptions with different type parameters in the catch clause, thus generic exceptions are not supported.

Should I catch generic exceptions?

So in general, catching generic exceptions is bad unless you are 100% sure that you know exactly which kinds of exceptions will be thrown and under which circumstances. If in doubt, let them bubble up to the top level exception handler instead. A similar rule here is never throw exceptions of type System. Exception.

Is it bad to throw a generic exception?

The primary reason why one should avoid throwing Generic Exceptions, Throwable, Error etc is that doing in this way prevents classes from catching the intended exceptions. Thus, a caller cannot examine the exception to determine why it was thrown and consequently cannot attempt recovery.

Why does Java not allow generic exception classes?

It’s essentially because it was designed in a bad way. The fact that a catch clause would fail for generics are not reified is no excuse for that. The compiler could simply disallow concrete generic types that extend Throwable or disallow generics inside catch clauses.

Why catching all exceptions is bad?

Also when you catch all exceptions, you may get an exception that cannot deal with and prevent code that is upper in the stack to handle it properly. The general principal is to catch the most specific type you can. catch(Exception) is a bad practice because it catches all RuntimeException (unchecked exception) too.

Is it good to use printStackTrace?

printStackTrace() is actually useful, it often turns out that invoking it is a bad practice. Extending the argument in the one of the previous paragraphs, it is also a poor choice to use Throwable. printStackTrace in conjunction with a logger that writes to the console.

Why do we need generic in Java?

In a nutshell, generics enable types (classes and interfaces) to be parameters when defining classes, interfaces and methods. Much like the more familiar formal parameters used in method declarations, type parameters provide a way for you to re-use the same code with different inputs.

What are the benefits of generics in Java?

Generics allow the programmer to use the same method for Integer arrays, Double arrays, and even String arrays. Another advantage of using generics is that Individual typecasting isn’t required. The programmer defines the initial type and then lets the code do its job. It allows us to implement non-generic algorithms.

How do you declare a generic variable in Java?

A Generic Version of the Box Class To update the Box class to use generics, you create a generic type declaration by changing the code “public class Box” to “public class Box”. This introduces the type variable, T, that can be used anywhere inside the class.

Is it good to catch generic exception?

Can we use try inside catch?

Yes, we can declare a try-catch block within another try-catch block, this is called nested try-catch block.

Can we write try-catch inside finally block?

A try-finally block is possible without catch block. Which means a try block can be used with finally without having a catch block.

Should I throw generic exception?

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