If you want both halves of the split pane to share in the split pane’s extra or removed space, set the resize weight to 0.5: (Tutorial) JSplitPane mainSplittedPane = new JSplitPane(JSplitPane.VERTICAL_SPLIT, upperPanel,bottomPanel); mainSplittedPane.setOneTouchExpandable(true); mainSplittedPane.setResizeWeight(0.5);
Instead of setPreferredSize(), let your components calculate their own preferred size and pack() the enclosing Window to accommodate. The example below adds an instance of draw.GraphPanel to the top and a corresponding control panel to the bottom. import draw.GraphPanel; import java.awt.EventQueue; import java.awt.GridLayout; import javax.swing.JFrame; import javax.swing.JPanel; import javax.swing.JScrollPane; import javax.swing.JSplitPane; /** * @see https://stackoverflow.com/q/11942961/230513 … Read more