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What is exception chaining in Java?

Tarun Telang

Grokking Modern System Design Interview for Engineers & Managers

Ace your System Design Interview and take your career to the next level. Learn to handle the design of applications like Netflix, Quora, Facebook, Uber, and many more in a 45-min interview. Learn the RESHADED framework for architecting web-scale applications by determining requirements, constraints, and assumptions before diving into a step-by-step design process.

Overview

Exception chaining occurs when one exception causes another exception. The original exception is the cause of the second exception.

In Java, a chained exception is an exception that is caused by another exception. Chained exceptions are associated such that the previous exception causes each exception in the chain. It can help debug, as it can help us track down the root cause of an error.

Exception chaining

We can use exception chaining in situations where another exception causes one exception. However, it's important to note that chaining can make our code more difficult to read and understand. Therefore, we should use exception chaining sparingly and only when necessary.

If we use chained exceptions, it is a good idea to document the chain in our code. It'll help others understand our code and make it easier to debug if an error occurs.

Example

For example, if an InputStream throws an IOException, and the InputStream's read() method throws an EOFException, then the EOFException is the cause of the IOException. The following code demonstrates the use of chained exceptions:

main.java
file.txt
import java.io.*;
class ChainedExceptionDemo {
public static void main(String[] args) throws IOException{
try {
throw new IOException("IOException encountered")
.initCause(new EOFException("root cause is EOFException"));
} catch (Throwable e) {
// Handle the IOException
System.out.println("Caught exception -> " + e);
// Handle the EOFException here
EOFException eof = (EOFException) e.getCause();
System.out.println("The cause is -> " + eof);
}
}
}
Code example showing usage of exception chaining

In the above code, exception chaining allows us to handle both exceptions in a single catch block. If we want to access the original exception (the "cause"), we can use the getCause() method.

Conclusion

In this Answer, we learned about chained exceptions in Java, how they are useful for debugging, and how to create a chain of exceptions. We also learned how to access the original exception (the "cause") by calling the getCause() method on the exception.

RELATED TAGS

java

Grokking Modern System Design Interview for Engineers & Managers

Ace your System Design Interview and take your career to the next level. Learn to handle the design of applications like Netflix, Quora, Facebook, Uber, and many more in a 45-min interview. Learn the RESHADED framework for architecting web-scale applications by determining requirements, constraints, and assumptions before diving into a step-by-step design process.

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