If you're seeing this page, it's probably because you've put excessively long lines inside Code Tags.
And this applies to regular Java code AND comments.
For starters, it's bad practice. Forcing people to look at extremely long lines is just as bad as crowding all your code together, using excessively long (or short) names, or not indenting properly.
Secondly, it messes up the window formatting here, making threads hard to read; so you're basically shooting yourself in the foot. Making code easy for others to read will get you your answers quicker.
In the olden days, coding sheets were 80 characters long, and it's still a good rule of thumb to follow; so if you find you're writing lines longer than that, break them up.
In some cases this may mean breaking up long Strings into manageable pieces and concatenating them with the '+' operator, but please remember to do it.
Don't "Quote" code with long lines in it - This has exactly the same effect as the original bad code, and makes it doubly difficult to clean up the thread since now two people are involved.
Don't use TABs for indentation - They are interpreted differently on different systems, and usually create excessive space. 2-4 spaces/indent is generally preferable.
Don't simply 'cut and paste' code - At least not without checking what it's going to look like BEFORE you post it.
Indeed, you shouldalways use the 'Preview' button to check what you write before you post it.