java - 将多个 JPanel 放置在彼此之上

Question

我有这段代码，它创建一个 JPanel 并将其添加到 JScrollPanel 中。它工作正常，但是当我尝试添加第二个 JPanel 时，它会删除第一个 JPanel 并添加第二个 JPanel。我希望能够将 JPanel 放置在 JPanel 之上，我该怎么做？

// Location of an image:
String file = wfc.getSelectedFile().getPath();

// Creates images from different types:
ImageHandler image = new ImageHandler();
BufferedImage imageData = image.imageData(file);

// Extends JPanel, Layer is a JPanel
Layer layer = new Layer(image.width(), image.height());
layer.setImage(imageData);
layer.setSizeFromLoaded();
// A list of all the JPanels added
Layers.set(Layers.layers.size(), layer);

// Adds a JPanel to the JScrollPanel
imagePane.getViewport().add(layer, BorderLayout.CENTER);

这是完整的方法，它打开一个文件浏览器，然后当选择图像时运行上面的代码

private void jMenuItem1ActionPerformed(java.awt.event.ActionEvent evt) {
    WebFileChooser wfc = null;
    if(wfc == null){
        wfc = new WebFileChooser(this, "Open an Image");
        wfc.setSelectionMode(SelectionMode.SINGLE_SELECTION);
        wfc.setAvailableFilter(GlobalConstants.IMAGES_AND_FOLDERS_FILTER);
        wfc.setChooseFilter(GlobalConstants.IMAGES_FILTER);
        wfc.setCurrentDirectory("/Users");
    }
    wfc.setVisible(true);

    if(wfc.getResult() == StyleConstants.OK_OPTION){
        String file = wfc.getSelectedFile().getPath();

        ImageHandler image = new ImageHandler();
        BufferedImage imageData = image.imageData(file);

        Layer layer = new Layer(image.width(), image.height());
        layer.setImage(imageData);
        layer.setSizeFromLoaded();
        Layers.set(Layers.layers.size(), layer);

        imagePane.getViewport().add(layer, BorderLayout.CENTER);
    }
}

Answer 1

您可能希望考虑将面板放入使用 CardLayout 的单个主面板中。 .

这将允许您轻松地在面板之间切换，从而产生分层面板的错觉，而无需手动执行此操作的麻烦。

类似...

JPanel master = new JPanel(new CardLayout());
master.add(new ChildPane()); // Or what ever child you want to add
master.add(new ChildPane()); // Or what ever child you want to add
//...
JScrollPane scrollPane = new JScrollPane(master);