Eclipse format question

When I format in eclipse long lines become from this :

String str = instance.someMethod("jhdajhajsha").someOtherMethod("sakjsaksja"); 

to this :

String str = instance.someMethod("jhdajhajsha")
                         .someOtherMethod("sakjsaksja"); 

How do I prevent this?

Good practice is to place line-break like that.
Any way you can edit you format setting

Window > Preferences   

It will show the Preferences Window
In that Expand the Java then Code Style and select Formatter
Here you can edit Active profile
In the edit, Line Wrapping tab, The General Settings there is a option to set the
Maximum line width give the maximum limit here, When you format, it will break the line more than this limit

windows > preferences > java > code style > formatter

Create a new profile. in the profile setting, select Line Wrapping [tab]

disable line wrapping for all . (class declaration, constructor declaration etc etc etc.. )