Exception Handling
What is an exception in Java?
Exception is abnormal behaviour that occurs at time of execution of an application which could get terminated if not handled properly.
What is exception handling in Java and what are the advantages of exception handling?
Exception handling is techniques provided by Java to avoid termination of application and maintain normal execution flow.
How are exceptions handled in Java?
try-catch block - Section where code is normally executed and monitored for any possible executions
finally block
- If any exception is thrown or not, it will get executed.
- It will not execute if System.exit(0) is present in either try or catch block
try-with-resources
If code ran properly or not, we want to close the resources. We can use like below.
try (Scanner sc = new Scanner(System.in)) {
return Integer.parseInt(sc.nextLine());
} catch (Exception e) {
log.info("Exception Handled");
}What is exception propagation in Java?
If an exception happens and it is not handled in the method where it was called, it goes down the call stack of preceding method and if it's still not caught, it propagates down to main method. If it's not handled in main method, program gets terminated.
What are the important methods defined in Java’s Exception Class?
String getMessage() - Returns the throwable message of type string
synchronized Throwable getCause() - Returns exception case if present else null
String toString() - Returns throwable information in string format
void printStackTrace() - Prints stack trace data to standard error stream. Default - Console, overloaded - PrintWriter or PrintStream
What are runtime exceptions in Java?
Exceptions that are not detected during compile time. They occur during execution of program.
They are also called unchecked exceptions.
All subclasses of java.lang.RunTimeException class and java.lang.Error class belongs to runtime exceptions.
What is the difference between the throw and throws keywords in Java?
throw - It can be used by programmer to throw exception object to interrup normal program flow. throws - It is used along with method signature to specify exceptions that method could throw during exception.
How do you handle checked exceptions?
It can be handled using try-catch block or by using throws clauses in method declaration. If not handled properly, then program would not compile.