Question

当我将一个JScrollPane添加到JPanel时，JPanel中的所有按钮都会消失，它会变空。我正在关注此帖here以及其他类似帖子。

以下是没有JScrollPane的代码：

* {box-sizing:border-box}

/* Slideshow container */
.slideshow-container {
  max-width: 1000px;
  position: relative;
  margin: auto;
}

.mySlides {
    display: none;
}

/* Slide Images */

.slide-img {
  width: 100%;
}

.dot-control {
  text-align: center;
}

/* Next & previous buttons */
.prev, .next {
  cursor: pointer;
  position: absolute;
  top: 50%;
  width: auto;
  margin-top: -22px;
  padding: 16px;
  color: white;
  font-weight: bold;
  font-size: 18px;
  transition: 0.6s ease;
  border-radius: 0 3px 3px 0;
}

/* Position the "next button" to the right */
.next {
  right: 0;
  border-radius: 3px 0 0 3px;
}

/* On hover, add a black background color with a little bit see-through */
.prev:hover, .next:hover {
  background-color: rgba(0,0,0,0.8);
}

/* Caption text */
.text {
  color: #f2f2f2;
  font-size: 15px;
  padding: 8px 12px;
  position: absolute;
  bottom: 8px;
  width: 100%;
  text-align: center;
}

/* Number text (1/3 etc) */
.numbertext {
  color: #f2f2f2;
  font-size: 12px;
  padding: 8px 12px;
  position: absolute;
  top: 0;
}

/* The dots/bullets/indicators */
.dot {
  cursor:pointer;
  height: 13px;
  width: 13px;
  margin: 0 2px;
  background-color: #bbb;
  border-radius: 50%;
  display: inline-block;
  transition: background-color 0.6s ease;
}

.active, .dot:hover {
  background-color: #717171;
}

/* Fading animation */
.fade {
  -webkit-animation-name: fade;
  -webkit-animation-duration: 1.5s;
  animation-name: fade;
  animation-duration: 1.5s;
}

@-webkit-keyframes fade {
  from {opacity: .4} 
  to {opacity: 1}
}

@keyframes fade {
  from {opacity: .4} 
  to {opacity: 1}
}

给出了：

使用JScrollPane的代码，最后一行替换为：

    JPanel panel = new JPanel();
    panel.setBorder(new BevelBorder(BevelBorder.LOWERED, null, null, null, null));
    panel.setBounds(5, 5, 286, 573);
    contentPane.add(panel);
    panel.setLayout(null);

    JPanel panel_1 = new JPanel();
    panel_1.setBorder(new BevelBorder(BevelBorder.LOWERED, null, null, null, null));
    panel_1.setBounds(12, 53, 262, 484);
    panel.add(panel_1);
    panel_1.setLayout(null);

    //this panel is the one the scrollPane is being added to and contains the buttons
    JPanel panel_2 = new JPanel();
    panel_2.setBounds(12, 68, 238, 403);
    panel_2.setLayout(new BoxLayout(panel_2, BoxLayout.Y_AXIS));

    for(int i = 0; i < 50; i++) {
        JButton bttn = new JButton("TEST");
        panel_2.add(bttn);
        panel_2.revalidate();

    }
    panel_1.add(panel_2);

但是，所有按钮都会消失：

编辑：以下是完整代码：

JScrollPane scrollPane = new JScrollPane(panel_2);
panel_1.add(scrollPane);
//panel_1.add(panel_2);

这是整个应用程序的图像;结果选项卡下面的面板带有＆＃34; TEST＆＃34;按钮是滚动窗格的位置：

非常感谢任何帮助！

Answer 1

你的约束有点奇怪：

    sl_panel_1.putConstraint(SpringLayout.NORTH, scrollPane, 0, SpringLayout.NORTH, panel_1);
    sl_panel_1.putConstraint(SpringLayout.WEST, scrollPane, 0, SpringLayout.WEST, panel_1);
    sl_panel_1.putConstraint(SpringLayout.SOUTH, scrollPane, 0, SpringLayout.NORTH, panel_1);
    sl_panel_1.putConstraint(SpringLayout.EAST, scrollPane, 0, SpringLayout.WEST, panel_1);

改为，例如：

    sl_panel_1.putConstraint(SpringLayout.NORTH, scrollPane, 0, SpringLayout.SOUTH, separator);
    sl_panel_1.putConstraint(SpringLayout.WEST, scrollPane, 0, SpringLayout.WEST, panel_1);
    sl_panel_1.putConstraint(SpringLayout.SOUTH, scrollPane, 0, SpringLayout.SOUTH, panel_1);
    sl_panel_1.putConstraint(SpringLayout.EAST, scrollPane, 0, SpringLayout.EAST, panel_1);

并且不要将panel_2的约束添加到sl_panel_1。

如果您添加了带有这些约束的panel_2且没有滚动窗格，则它也不会显示

添加JScrollPane会删除JPanel中的所有组件

1 个答案: