The difference between Java exception and error

The abstract class of exceptions in Java is Throwable, which is based on the derivation of two main classes: Error and exception.

Error is a serious error in the program and should not be included with Try...catch. Javadoc's instructions are as follows:

An Error was a subclass of Throwable that indicates serious problems, a reasonable application should not a try to catch. Most such errors is abnormal conditions.

Common error is: Assertionerror, OutOfMemoryError, Stackoverflowerror.

Exception is divided into two categories: Checked Exception and unchecked Exception.
The base class of unchecked Exception is runtimeexception, and all Exception inherited from runtimeexception belong to unchecked Exception, such as: NullPointerException, ArrayIndexOutOfBoundsException.
Checked Exception directly inherits from Exception, all Exception that do not inherit runtimeexception belong to Checked Exception, such as: FileNotFoundException.

Checked exception and unchecked exception can all be included with Try...catch. Where Checked exception checks for the desired catch handling at compile time, it is necessary to have try...catch included, or the corresponding exception is thrown at the method signature. And unchecked exception is judged at run time, so it doesn't have to be try...catch included. Moreover, unchecked exception is often a bug in the program itself, generally does not catch such errors.

Note 1:
Executing a return statement in a try will still execute a finally statement block unless the JVM process is ended in a try statement (System.exit (0))

public  class  hello  { public  static  void  main  (string[] args) {try  {System.out.println            ( "in Try" );        return ; }catch  (Exception e) {}finally  {syste        M.out.println ( "finally" );    } System.out.println ( "end" ); }}//output  in try   Finally   

Note 2:
do not call return in the Finally statement block, otherwise the exception thrown in the try statement block cannot be captured by the caller, as follows:

 try  {dosomething (); System.    out . println ( "No Exception caught!" ); } catch  (runtimeexception e) {system.. println (); }} public  static   void  dosomething  () {try  {throw  new  runtimeexception ();    } finally  {return ; }}//output  No Exception caught!  

Note 3:
The difference between throw and throws:
Throw is in the statement block, and the programmer actively throws an exception.
Throws is the signature of the method that describes the exception that the method might throw. When multiple exceptions are thrown, separate them with commas.

Note 4:
Starting with JDK7, multiple catch corresponding to the same try can be written together.

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The difference between Java exception and error