Java Look and Feel Layout Guidelines

All illustrations borrowed from the Java Look and Feel Design Guidelines, Second Edition, available online or in bookstores.
Alignment of Related Options and Vertical Separation of Component Groups

Horizontal Separation of User Interface Elements

Spacing and Padding in Command Button Groups

Perceived and Actual Spacing of Available and Unavailable Components

Spacing of Multiple Groups of Components

Toolbar Button Spacing

Spacing Between Independent Toggle Buttons

Vertical Separation of Command Buttons

Spacing Between Border and Components of a Dialog Box

Checkbox Layout

Spacing Between a Label and a Component

Label Placement

Spacing for a Panel With Titled Border

Checkbox and Radio Button Spacing

Spacing of Exclusive Toggle Buttons