Question

问题是我有多个面板在那个mainpane停留在centre.using一个for循环我添加了1000个按钮到主面板。我添加了一个主窗格的滚动窗格。但我无法滚动。我尝试了来自stackoverflow的很多帖子的解决方案，但我无法解决请帮帮我

  public class Products extends Applet {

private static final long serialVersionUID = -5897268039244126279L;
JPanel mainpane=new JPanel();
JPanel toppane=new JPanel();
JPanel leftpane=new JPanel()
{
    public void paintComponent(Graphics g)
    {
        g.drawImage(img.getI![enter image description here][1]mage(),0,0,200,500,null);
    }
}
;
JPanel total=new JPanel();
JPanel rightpane=new JPanel();
ImageIcon img=new ImageIcon(getClass().getResource("biskate.jpg"));
private void initialise() {

    total.setPreferredSize(new Dimension(1366,650));
         leftpane.setPreferredSize(new Dimension(200,500));
         rightpane.setPreferredSize(new Dimension(266,500));
         mainpane.setPreferredSize(new Dimension(900,500));
         mainpane.setLayout(new FlowLayout());
         toppane.setPreferredSize(new Dimension(1366,150));
         total.setLayout(new BorderLayout());
         leftpane.setBackground(Color.WHITE);   
         mainpane.setBackground(Color.BLUE);

         toppane.setBackground(Color.WHITE);
         rightpane.setBackground(Color.magenta);

         total.add(leftpane,BorderLayout.WEST);
            total.add(rightpane,BorderLayout.EAST);

JScrollPane scroll=new JScrollPane(mainpane,ScrollPaneConstants.VERTICAL_SCROLLBAR_AS_NEEDED,ScrollPaneConstants.HORIZONTAL_SCROLLBAR_NEVER);
        //  scroll.setPreferredSize(new Dimension(600,600));
            //scroll.getViewport().add(mainpane);
            total.add(scroll,BorderLayout.CENTER);

            total.add(toppane,BorderLayout.NORTH);
            add(total);

}


             JCheckBox arr[];
            BufferedImage image;
            JLabel look=new JLabel(img);
             public void init()
             {
               this.setSize(1366,650);

        initialise();
                arr=new JCheckBox[6];

    String []s={"Rs. 2000 and Below","Rs. 2001 - Rs. 5000","Rs. 5001 - Rs. 10000","Rs. 10001 - Rs. 18000",
            "Rs. 18001 - Rs. 25000","Rs. 25001 - Rs. 35000"};
    leftpane.add(new JLabel("Choose price range"));

    for(int i=0;i<6;i++)
    {
     arr[i]=new JCheckBox(s[i]);
     arr[i].setBackground(Color.YELLOW);
     leftpane.add(arr[i]);
    }
    addgrid();
        }
        private void addgrid()
        {
          for(int i=0;i<1000;i++)
            {
           mainpane.add(new JButton("holy"+" "+i));
            } 

         }

Answer 1

//leftpane.setPreferredSize(new Dimension(200,500));
//rightpane.setPreferredSize(new Dimension(266,500));
//mainpane.setPreferredSize(new Dimension(900,500));
//mainpane.setLayout(new FlowLayout());
//toppane.setPreferredSize(new Dimension(1366,150));

不要在任何组件上使用setPreferredSize（）。面板的布局管理器确定面板的首选大小。然后，滚动条将在需要时自动显示。

此外，FlowLayout是面板的默认布局，因此您无需再次手动设置布局。

我无法在java中滚动面板的内容

1 个答案: