Java exception: try... catch... finally

Before reading the following content, I would like to ask you a question:

Will finally statements be executed?

 

Use the Integer. valueOf method to simulate an exception to illustrate the problem between try catch and finally.

 

Example 1: no exception, normal

[Java]
Public class TryCatchFinally {
 
Public static void main (String [] args ){
Try {
System. out. println ("try statement :-)");
Integer. valueOf ("2 ");
} Catch (NumberFormatException nfe ){
System. out. println ("catch statement :-)");
} Finally {
System. out. println ("finally statement :-)");
}
}
}

Example 2: no exception, normal, but add return in the try statement
[Java]
Public class TryCatchFinally {
 
Public static void main (String [] args ){
Try {
System. out. println ("try statement :-)");
Integer. valueOf ("2 ");
Return;
} Catch (NumberFormatException nfe ){
System. out. println ("catch statement :-)");
} Finally {
System. out. println ("finally statement :-)");
}
}
}

The running results of Example 1 and Example 2 are the same:

 

 

Example 3: Manufacturing exception

[Java]
Public class TryCatchFinally {
 
Public static void main (String [] args ){
Try {
System. out. println ("try statement :-)");
Integer. valueOf ("bluetooth ");
} Catch (NumberFormatException nfe ){
System. out. println ("catch statement :-)");
} Finally {
System. out. println ("finally statement :-)");
}
}
}

Example 4: create an exception. Add return to the catch statement.

[Java]
Public class TryCatchFinally {
 
Public static void main (String [] args ){
Try {
System. out. println ("try statement :-)");
Integer. valueOf ("bluetooth ");
} Catch (NumberFormatException nfe ){
System. out. println ("catch statement :-)");
Return;
} Finally {
System. out. println ("finally statement :-)");
}
}
}

The running result of Example 3 and Example 4 is the same:

 

 

From this, we can see that the finally statements are executed in the above four cases.

 

Example 5: create an exception. Add return to the catch statement.

 

Purpose: To verify whether the code behind the finally code block is executed ??????

[Java]
Public class TryCatchFinally {
 
Public static void main (String [] args ){
Try {
System. out. println ("try statement :-)");
Integer. valueOf ("bluetooth ");
} Catch (NumberFormatException nfe ){
System. out. println ("catch statement :-)");
Return;
} Finally {
System. out. println ("finally statement :-)");
}
 
System. out. println ("out of try... catch... finally statement ");
}
}

Execution result:

 

 

If you comment out the return in the catch statement, the execution result is as follows:

 

 

Example 6: create an exception. Add return to the try statement.

[Java]
Public class TryCatchFinally {
 
Public static void main (String [] args ){
Try {
System. out. println ("try statement :-)");
Integer. valueOf ("dd ");
Return;
} Catch (NumberFormatException nfe ){
System. out. println ("catch statement :-)");
} Finally {
System. out. println ("finally statement :-)");
}
 
System. out. println ("out of try... catch... finally statement ");
}
}

Execution result:

 

 

Example 7: no exception. Add return in the try statement.

[Java]
Public class TryCatchFinally {
 
Public static void main (String [] args ){
Try {
System. out. println ("try statement :-)");
Integer. valueOf ("2 ");
Return;
} Catch (NumberFormatException nfe ){
System. out. println ("catch statement :-)");
} Finally {
System. out. println ("finally statement :-)");
}
 
System. out. println ("out of try... catch... finally statement ");
}
}

Execution result (no exception, return returns, so the statement after the finally code block will not execute :-)

 

 

The above indications indicate:

 

All finally statements have been executed, but there is another situation that has not been verified. Next let's look at it.

 

Exit JVM in try... catch:

 

[Java]
Public class TryCatchFinally {
 
Public static void main (String [] args ){
Try {
System. out. println ("try statement :-)");
Integer. valueOf ("2eer ");
System. exit (0 );
} Catch (NumberFormatException nfe ){
System. out. println ("catch statement :-)");
System. exit (0 );
} Finally {
System. out. println ("finally statement :-)");
}
 
System. out. println ("out of try... catch... finally statement ");
}
}

Execution result:

 

 

If System. exit is called in a try or catch Statement (any one), the finally statement will not be executed.

 

Author: AndroidBluetooth