[英]Image not loading onto JPanel?
我一直在试图找出如何将图像添加到JPanel作为背景,但是仍然完全控制JButton,JLabel等的放置。这是我发现的一种方法,但是它崩溃了并且没有加载图像或按钮。 这是代码:
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JButton;
import java.awt.BorderLayout;
import java.awt.FlowLayout;
import java.awt.GridLayout;
public class PanelDemo extends JFrame {
private static final long serialVersionUID = 1L;
private JButton btn1 = new JButton("EASY");
private JButton btn2 = new JButton("MEDIUM");
private JButton btn3 = new JButton("HARD");
private JButton btn4 = new JButton("High Score");
public PanelDemo() {
super("Image Panel Demo");
JPanel panel = new ImagePanel(
new FlowLayout(FlowLayout.CENTER, 50, 180));
JPanel panelbtn = new JPanel(new GridLayout(4, 1));
btn1.setBackground(new java.awt.Color(0, 0, 0));
btn1.setFont(new java.awt.Font("Showcard Gothic", 1, 24));
btn1.setForeground(new java.awt.Color(0, 255, 102));
btn2.setBackground(new java.awt.Color(0, 0, 0));
btn2.setFont(new java.awt.Font("Showcard Gothic", 1, 24));
btn2.setForeground(new java.awt.Color(0, 255, 102));
btn3.setBackground(new java.awt.Color(0, 0, 0));
btn3.setFont(new java.awt.Font("Showcard Gothic", 1, 24));
btn3.setForeground(new java.awt.Color(0, 255, 102));
btn4.setBackground(new java.awt.Color(0, 0, 0));
btn4.setFont(new java.awt.Font("Showcard Gothic", 1, 24));
btn4.setForeground(new java.awt.Color(0, 255, 102));
panel.add(panelbtn);
panelbtn.add(btn1);
panelbtn.add(btn2);
panelbtn.add(btn3);
panelbtn.add(btn4);
add(panel, BorderLayout.CENTER);
setSize(640, 480);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
public static void main(String... args) {
new PanelDemo().setVisible(true);
}
}
ImagePanel.java
import java.awt.Graphics;
import java.awt.Image;
import java.awt.LayoutManager;
import javax.swing.ImageIcon;
import javax.swing.JPanel;
public class ImagePanel extends JPanel {
private static final long serialVersionUID = 1L;
String imageFile = "/rsc/img/background.jpg";
public ImagePanel() {
super();
}
public ImagePanel(String image) {
super();
this.imageFile = image;
}
public ImagePanel(LayoutManager layout) {
super(layout);
}
public void paintComponent(Graphics g) {
ImageIcon imageicon = new ImageIcon(getClass().getResource(imageFile));
Image image = imageicon.getImage();
super.paintComponent(g);
if (image != null)
g.drawImage(image, 0, 0, getWidth(), getHeight(), this);
}
}
错误:
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at javax.swing.ImageIcon.<init>(Unknown Source)
at ImagePanel.paintComponent(ImagePanel.java:27)
at javax.swing.JComponent.paint(Unknown Source)
at javax.swing.JComponent.paintChildren(Unknown Source)
at javax.swing.JComponent.paint(Unknown Source)
at javax.swing.JComponent.paintChildren(Unknown Source)
at javax.swing.JComponent.paint(Unknown Source)
at javax.swing.JLayeredPane.paint(Unknown Source)
at javax.swing.JComponent.paintChildren(Unknown Source)
at javax.swing.JComponent.paintToOffscreen(Unknown Source)
at javax.swing.RepaintManager$PaintManager.paintDoubleBuffered(Unknown Source)
at javax.swing.RepaintManager$PaintManager.paint(Unknown Source)
at javax.swing.RepaintManager.paint(Unknown Source)
at javax.swing.JComponent.paint(Unknown Source)
at java.awt.GraphicsCallback$PaintCallback.run(Unknown Source)
at sun.awt.SunGraphicsCallback.runOneComponent(Unknown Source)
at sun.awt.SunGraphicsCallback.runComponents(Unknown Source)
at java.awt.Container.paint(Unknown Source)
at java.awt.Window.paint(Unknown Source)
at javax.swing.RepaintManager$3.run(Unknown Source)
at javax.swing.RepaintManager$3.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at javax.swing.RepaintManager.paintDirtyRegions(Unknown Source)
at javax.swing.RepaintManager.paintDirtyRegions(Unknown Source)
at javax.swing.RepaintManager.prePaintDirtyRegions(Unknown Source)
at javax.swing.RepaintManager.access$1000(Unknown Source)
at javax.swing.RepaintManager$ProcessingRunnable.run(Unknown Source)
at java.awt.event.InvocationEvent.dispatch(Unknown Source)
at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
at java.awt.EventQueue.access$200(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)
另外,如果有人知道将背景图像放在JPanel上的更好方法,请告诉我。 先感谢您。
String imageFile = "/rsc/img/background.jpg";
我认为您不应使用前导“ /”。 这意味着在C:驱动器的根目录下查找目录“ rsc”。
有关加载图像的示例,请参见有关如何使用图标的Swing教程。
btn1.setFont(new java.awt.Font("Showcard Gothic", 1, 24));
作为旁注,为什么要为每个按钮创建一个新的Font对象。 您可以创建一个实例,然后将该实例添加到所有按钮中。
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.