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Java Java Objects (Retired) Harnessing the Power of Objects Exceptions

Steven Wheeler
Steven Wheeler
2,330 Points
Posted by Steven Wheeler
Steven Wheeler
2,330 Points

Why does "println" not work but "printf" does in "Exceptions" lesson?

Hey there!

Out of interest why does "printf" work here (3rd line): "catch (IllegalArgumentException iae) { System.out.println("Woah there!"); System.out.printf("There was an error: %s", iae.getMessage()); }"

but if we were to use "println" it goes crazy?

Thanks! :)

3 Answers

Craig Dennis
STAFF
Craig Dennis
Treehouse Teacher
Craig Dennis
Craig Dennis
Treehouse Teacher

printf is for printing formatted text and takes additional parameters. println is for printing lines of text and does not do substitution.

Make sense?

Mario Blokland
Mario Blokland
19,750 Points
Mario Blokland
Mario Blokland
19,750 Points

Hi Steven Wheeler, 

System.out.println("")

can only print an unformatted string. Thus, if you would leave the %s out of the String everything would work as expected. 

System.out.printf("") // The f in printf stands for formatted

this version can print regular strings and formatted strings e.g. %s, %d and so on. If you put %s in the string you are using the formatted version and replace the placeholder %s with some string.

I hope that cleared things up a little bit for you.

Mario Blokland
Mario Blokland
19,750 Points

Oh, just saw that Craig was faster than me and already answered your question :-)

Steven Wheeler
Steven Wheeler
2,330 Points
Steven Wheeler
Steven Wheeler
2,330 Points

Excellent, makes sense! Thanks guys!