Hierarchy of Exceptions
Unchecked Exceptions
Following Exceptions appear in the category of Unchecked exception
- ArithmeticException
- ArrayIndexOutOfBoundsException
- NullPointerException
Runtime Exceptions are the ones that are not checked at compile time. Rather they appear at the runtime .
- ArithmeticException - dividing a number from ‘0’ throws Exception in thread "main" java.lang.ArithmeticException: / by zero
- ArrayIndexOutOfBoundsException - Trying to access an index that does not exists
| int arr[] = {'0','1','2'};
System.out.println(arr[4]);
|
- NullPointerException - Trying to access a null object
| String string = null; |
| System.out.println(string.length()); |
Checked Exceptions
Exceptions that are checked at compile-time are called checked exceptions
- FileNotFoundException
- ParseException
- ClassNotFoundException
- CloneNotSupportedException
- InstantiationException
- InterruptedException
- NoSuchMethodException
- NoSuchFieldException
In certain situations (In case of Checked Exceptions) Java compiler force the programmer to write a handling code to deal with exceptions. For example let’s assume we are having a code that reads from an external file, JVM expects some handling code for the situation if the required file is not available at the run time. This is how Java maintains its integrity against code failure by allowing the programmer to write handling code for failure prone areas of code.
These are the ones for which we have already written Exception handler in the code at compile time, the Exceptions thrown in such situation are called Checked Exception.
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