BorderLayout

BorderLayout is a layout manager used in Java AWT and Swing that arranges components into five regions: North, South, East, West, and Center. It is part of java.awt.BorderLayout and is commonly used as the default layout for containers such as a JFrame’s content pane. The layout responds to container resizing by adjusting the size of components in each region, with the Center region taking any remaining space after the others are laid out.

Each region has specific sizing behavior: North and South extend horizontally across the full width, preserving their preferred height; East and West extend vertically along the sides, preserving their preferred width; Center expands to fill the remaining space. If a region is empty, others resize as needed; only one component should occupy a given region, though a region can host a nested container with its own layout.

Components are placed in a region by providing a constraint such as BorderLayout.NORTH when adding: container.setLayout(new BorderLayout()); container.add(someComponent, BorderLayout.NORTH); You can also use strings like "North" as constraints. The layout manager implements LayoutManager and LayoutManager2, and supports standard methods for computing preferred and minimum sizes and performing the actual positioning in layoutContainer.

Because of its simplicity, BorderLayout is a common choice for top-level frames and panels that require a stable, region-based arrangement. For more complex interfaces, it is common to nest panels with different layouts inside the regions.