我有一个两个类项目，一个类读取一个文件，并根据网站检查所述文件中的每个条目，并将返回数据发布到另一个文件中。
如果返回数据为真（例如），则文件中的数据点将在屏幕上闪烁。此功能有效。
我通过while循环中的以下if语句调用它。
if (!query.text().contains("unavailable") && !query.text().contains("at least 3 characters long to acquire.") && line != null) {
HitBox h = new HitBox(line); //GUI Class.
fos.write(query.text().getBytes());
fos.write("\n".getBytes());
fos.flush();
}
以下是我的GUI类。
import java.awt.AlphaComposite;
import java.awt.Color;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.io.IOException;
import javax.swing.ImageIcon;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JWindow;
import javax.swing.SwingUtilities;
import javax.swing.Timer;
import javax.swing.UIManager;
public class HitBox {
private Timer t;
JWindow frame = new JWindow();
public HitBox(String s) {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager
.getSystemLookAndFeelClassName());
} catch (Exception ex) {
}
frame.setAlwaysOnTop(true);
t = new Timer(1000 * 5, new ActionListener() {
public void actionPerformed(ActionEvent e2) {
SwingUtilities.getWindowAncestor(frame.getComponent(0))
.dispose();
}
});
}
});
frame.setBackground(new Color(0, 0, 0, 0));
TranslucentPane tp = new TranslucentPane(s);
frame.setContentPane(tp);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
t.start();
}
}
class TranslucentPane extends JPanel {
public TranslucentPane(String s) {
add(new JLabel(s));
setOpaque(false);
}
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
g2d.setComposite(AlphaComposite.SrcOver.derive(0.85f));
g2d.setColor(getBackground());
g2d.fillRect(0, 0, getWidth(), getHeight());
}
}
使用同一组输入数据会发生这种情况，即使我覆盖了Web查询，只返回一个设定值，@在运行时的随机点，JWindow将出现，将抛出一个nullpointer（@ my call of我的计时器对象的start方法。）
这让我相信我错误地实施了计时器;我对如何使用一致的数据和返回感兴趣，它会引发空指针的变化。
Exception in thread "main" java.lang.NullPointerException
at HitBox.<init>(HitBox.java:51)
at OriginalGangster.main(OriginalGangster.java:38)
答案 0 :(得分：4)
您没有在GUI线程上启动GUI。您需要将其移动到Runnable中，并确保在构建之后启动Timer 。
如，
import java.awt.AlphaComposite;
import java.awt.Color;
import java.awt.EventQueue;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JWindow;
import javax.swing.Timer;
import javax.swing.UIManager;
public class TestHitBox {
public static void main(String[] args) {
String text = "Hello world! This is Hovercraft!";
int seconds = 5;
float composite = 0.85f;
float points = 48f;
HitBox.showMessage(text, seconds, composite, points);
}
}
class HitBox {
public static void showMessage(final String text, final int seconds, final float composite, final float points) {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager
.getSystemLookAndFeelClassName());
} catch (Exception ex) {
ex.printStackTrace();
}
final JWindow frame = new JWindow();
frame.setBackground(new Color(0, 0, 0, 0));
TranslucentPane tp = new TranslucentPane(text, composite, points);
frame.setContentPane(tp);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
frame.setAlwaysOnTop(true);
new Timer(1000 * seconds, new TimerListener(frame)).start();
}
});
}
}
class TimerListener implements ActionListener {
private JWindow frame;
public TimerListener(JWindow frame) {
this.frame = frame;
}
@Override
public void actionPerformed(ActionEvent e) {
frame.dispose();
((Timer) e.getSource()).stop();
}
}
@SuppressWarnings("serial")
class TranslucentPane extends JPanel {
private float composite;
public TranslucentPane(String s, float composite, float points) {
this.composite = composite;
JLabel label = new JLabel(s);
label.setFont(label.getFont().deriveFont(Font.BOLD, points));
add(label);
setOpaque(false); // this breaks a rule
}
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
g2d.setComposite(AlphaComposite.SrcOver.derive(composite));
g2d.setColor(getBackground());
g2d.fillRect(0, 0, getWidth(), getHeight());
g2d.dispose(); // dispose of any graphics we create
}
}
代码已更新。