Question

我正在尝试实现一个按钮，用于激活在另一个窗口中绘制的线条。

我投了3个班：

Table_Workspace - 扩展JFrame类包含按钮;

Table_graph - 扩展JFrame类。除了其他之外，它还包含一个ActiveZone类型的元素

ActiveZone - 扩展JPanel类，它覆盖paintComponent函数：

=============================================== =================================

public class ActiveZone extends JPanel {
    @Override
    public void paintComponent(Graphics g) {
        // TODO Auto-generated method stub
        super.paintComponent(g);
        g.drawLine(1, 1, 20, 20);
        System.out.print("Add img");
    }
}

public class Table_Workspace extends JFrame {
//.....
btnBuild = new JButton("Build");
contentPane.add(btnBuild);
btnBuild.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                // TODO Auto-generated method stub
                ActiveZone activezone = new ActiveZone();
                Table_graph table_graph = new Table_graph(); //window in which we draw
                //sl_contentPane = SpringLayout() from Table_graph
                table_graph.sl_contentPane.putConstraint(SpringLayout.NORTH,
                        activezone, 0, SpringLayout.NORTH,
                        table_graph.GridPanel);
                table_graph.sl_contentPane
                        .putConstraint(SpringLayout.EAST, activezone, 0,
                                SpringLayout.EAST, table_graph.GridPanel);
                table_graph.sl_contentPane.putConstraint(SpringLayout.SOUTH,
                        activezone, 0, SpringLayout.SOUTH,
                        table_graph.GridPanel);
                table_graph.sl_contentPane
                        .putConstraint(SpringLayout.WEST, activezone, 0,
                                SpringLayout.WEST, table_graph.GridPanel);

                table_graph.contentPane.add(activezone, 0);
                table_graph.contentPane.revalidate();
                table_graph.contentPane.repaint();
                activezone.setOpaque(false);


            }
        });

=============================================== =================================

在执行期间，它不输出任何内容，在System.out中没有输出，也没有任何错误消息。

但是如果我从Table_Workspace获取组件创建代码把它放到Table_graph一切正常，然后绘制线条。像这样：

=============================================== ==================================

activezone = new ActiveZone();

sl_contentPane.putConstraint(SpringLayout.NORTH, activezone, 0,
                SpringLayout.NORTH, GridPanel);
sl_contentPane.putConstraint(SpringLayout.EAST, activezone, 0,
                SpringLayout.EAST, GridPanel);
sl_contentPane.putConstraint(SpringLayout.SOUTH, activezone, 0,
                SpringLayout.SOUTH, GridPanel);
sl_contentPane.putConstraint(SpringLayout.WEST, activezone, 0,
                SpringLayout.WEST, GridPanel);
contentPane.add(activezone, 0);
activezone.setOpaque(false);

=============================================== ===================================

请告诉我，什么是错的，我怎么能实现这个想法？

事先先谢谢你！

在另一个窗口中绘图

0 个答案: