FAQ How do I stop the Java editor from showing a single method at once?
Activate the editor area, and then click the toolbar button labeled Show Source of Selected Element Only.
People sometimes click this button by accident and end up stuck in a state in which the Java editor will show only a single method or field at once. This feature of the Java editor makes it much easier to work in large Java files. By focusing on a single method at once, you have a much less cluttered editor area. Note that you can still view the entire file when in this state by deselecting the selected element in the Outline view. Smalltalkers will recognize this as one of the many innovations Eclipse inherited from its non file-centric Smalltalk IDE ancestors.