Difference between revisions of "Exceptions"
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| + | == Introduction == | ||
* Exceptions are a mechanism to detect and handle errors without writing special code to test return values. | * Exceptions are a mechanism to detect and handle errors without writing special code to test return values. | ||
* Error handling code for common errors can be handled in a single place. | * Error handling code for common errors can be handled in a single place. | ||
| + | |||
| + | == Structure == | ||
| + | |||
* A try clause has to have either a catch clause or a finally clause or both. | * A try clause has to have either a catch clause or a finally clause or both. | ||
* catch must follow try. | * catch must follow try. | ||
* finally must follow the last catch clause. | * finally must follow the last catch clause. | ||
| + | |||
| + | == Exception Hierarchy == | ||
| + | |||
| + | * All exception classes are subtypes of java.lang.Exception. | ||
| + | * RunTimeException is a subtype of Exception which represents unchecked exceptions. All unchecked exception will inherit from this class. | ||
| + | * Classes which derive from java.lang.Error indicate serious problems that an application should not try to catch. e.g OutOfMemory error. | ||
| + | * Both Error and Exception classes are derived from the java.lang.Throwable class. | ||
| + | |||
| + | == Exception Matching == | ||
| + | |||
| + | |||
[[Category:OCPJP]] | [[Category:OCPJP]] | ||
Revision as of 22:01, 19 July 2011
Introduction
- Exceptions are a mechanism to detect and handle errors without writing special code to test return values.
- Error handling code for common errors can be handled in a single place.
Structure
- A try clause has to have either a catch clause or a finally clause or both.
- catch must follow try.
- finally must follow the last catch clause.
Exception Hierarchy
- All exception classes are subtypes of java.lang.Exception.
- RunTimeException is a subtype of Exception which represents unchecked exceptions. All unchecked exception will inherit from this class.
- Classes which derive from java.lang.Error indicate serious problems that an application should not try to catch. e.g OutOfMemory error.
- Both Error and Exception classes are derived from the java.lang.Throwable class.
