How to embed a grid layout inside a border layout in java

You're trying to add a component to a layout, and that simply cannot be done. Instead use a JPanel, give it a GridLayout, and then add the component to the JPanel (acting as the "container" here).

In general, you will want to nest JPanels with each using the best layout for the GUI, here the inner JPanel using GridLayout and the outer one using BorderLayout. Then you simply add the inner JPanel to the outer one (here your contentPane) in the BorderLayout.CENTER position.

Providing code visualization derived from Hovercraft's answer:

Display class:

public class Display extends JFrame     {

JPanel gridHolder = new JPanel(); // panel to store the grid
private GridLayout buttonsGrid; // space containing a buttons
private JButton myButtons[]; // grid is to be filled with these buttons
private BorderLayout mainGUILayout; // main gui layout
private Container mainGuiContainer;

public Display()     {
    mainGUILayout = new BorderLayout(5,5); // Border layout option
    mainGuiContainer = getContentPane(); // getting content pane
    mainGuiContainer.setLayout(mainFrameLayout); // setting main layout
    buttonsGrid = new GridLayout(4, 1, 5, 5); // 4 buttons one over the other
    myButtons = new JButton[4]; // player's hand represented with buttons
    gridHolder.setLayout(buttonsGrid);

                for (int x = 0; x < 4; x++)     {
                
                myButtons[x] = new JButton (" ");
                gridHolder.add(myButtons[x]);     }

            add(gridHolder, BorderLayout.WEST);
            setVisible(true);     }     }

MainGUILaunch class:

public class MainGUILaunch     {
    public static void main (String args[])     {
        Display myApplication = new Display();
        myApplication.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        myApplication.setSize(1024, 1024);
        myApplication.setVisible(true); // displaying application     }
} // End of MainGUILaunch