java - JPanel : how to add buttons above table?

Question

    JPanel panel = new JPanel();
    bigbutton = new JButton("Big Button");
    clearbutton = new JButton("Clear Page");
    resetbutton = new JButton("Start Over");
    finishbutton = new JButton("Finish");


    panel.add(sometable);
    return panel; 

现在发生的是它们水平蔓延。我想要水平和 table 上方的四个按钮。

Answer 1

right now what happens is they sprawl horizontally.

除了@tulskiy 和@Andrew Thompson 的建议之外，注意 JPanel 的默认布局可能很有用。是 FlowLayout ，它将组件排列在水平行中。

附录:

change JPanel's FlowLayout to BorderLayout or some other layout?

选择布局在一定程度上取决于品味，但我会结合建议的方法，如 How to Use Tool Bars 所示。 .注意如何 ToolBarDemo扩展 JPanel然后调用父类(super class)构造函数来指定 BorderLayout() :

public class ToolBarDemo extends JPanel implements ActionListener {
    ...
    public ToolBarDemo() {
        super(new BorderLayout());
        ...
        JToolBar toolBar = new JToolBar("Still draggable");
        addButtons(toolBar);
        ...
        setPreferredSize(new Dimension(450, 130));
        add(toolBar, BorderLayout.PAGE_START);
        add(sometable, BorderLayout.CENTER);
    }
    ...
}

没有扩展，直接使用构造函数即可:

JPanel panel = new JPanel(new BorderLayout());

或者，使用 setLayout() JPanel继承的方法.

JPanel panel = new JPanel();
panel.setLayout(new BorderLayout());