我有一个边框布局,我想在中心部分添加一个网格布局。但是,我不能声明一个网格,然后添加我的中心边框。我怎样才能做到这一点?
public Liability_Calculator(String s)
{
    super(s);
    setSize(325,200);
    
    c = getContentPane();
    c.setLayout(new BorderLayout());
    
    //the top label
    total = new JLabel("Total monthly liabilities ", JLabel.CENTER);
    c.add(total, BorderLayout.NORTH);
    
    
    //the grid
    GridLayout grid = new GridLayout(2,2);
    
    text_field1 = new JTextField(7);
    
    //I GET AN ERROR HERE!!!!!!!
    grid.add(text_field1);
    //AND ERROR HERE!!!!!!!!!!!!!
    c.add(grid, BorderLayout.CENTER);
    
    
    
    setVisible(true);
}