我目前正在使用 AWT Package 和 Swing 在 java 中制作模擬時鐘。但數字時鐘覆蓋目前每隔一段時間就會閃爍一次，我想解決這個問題。我讀過有關與 repaint() 結合實現雙緩沖的內容，但我對如何實現它感到困惑。import java.applet.Applet;import java.awt.BorderLayout;import java.awt.Color;import java.awt.Dimension;import java.awt.Font;import java.awt.Graphics;import java.text.SimpleDateFormat;import java.util.Calendar;import java.util.GregorianCalendar;import java.util.TimeZone;import java.util.Timer;import java.util.TimerTask;import javax.swing.JFrame;public class Clock2d extends Applet { GregorianCalendar cal; Timer clockTimer = new Timer(); TimeZone clockTimeZone = TimeZone.getDefault(); public Clock2d() { clockTimer.schedule(new TickTimerTask(), 0, 1000); } @Override public void init() { } public void paint(Graphics g) { g.setColor(Color.BLUE); g.fillOval(40, 40, 220, 220); g.setColor(Color.WHITE); g.fillOval(50, 50, 200, 200); double second = cal.get(Calendar.SECOND); double minute = cal.get(Calendar.MINUTE); double hours = cal.get(Calendar.HOUR); for (int i = 0; i < 60; i++) { int length = 90; double rad = (i * 6) * (Math.PI) / 180; if (i % 5 == 0) { length = 82; g.setColor(Color.BLUE); } else { g.setColor(Color.GRAY); } int x = 150 + (int) (95 * Math.cos(rad - (Math.PI / 2))); int y = 150 + (int) (95 * Math.sin(rad - (Math.PI / 2))); int x1 = 150 + (int) (length * Math.cos(rad - (Math.PI / 2))); int y1 = 150 + (int) (length * Math.sin(rad - (Math.PI / 2))); g.drawLine(x, y, x1, y1); }除了編號數字時鐘偶爾閃爍之外，代碼完全按照預期工作。
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猛跑小豬
TA貢獻1858條經驗 獲得超8個贊
public class Clock2d extends AppletAjava.awt.Applet不僅已被棄用，而且默認情況下也不是雙緩沖的。更改它以擴展 aJPanel（即）。然后改為
public void paint(Graphics g) {尊重public void paintComponent(Graphics g) { super.paintComponent(g);油漆鏈。class TickTimerTask extends TimerTask使用 ajavax.swing.Timer代替。它在事件調度線程上運行，對 GUI 的任何調用都應在 EDT 上進行。
這是代碼中表達的這三點。您在這個版本中看到“閃爍”的偽像嗎？
import java.awt.*;
import java.awt.event.*;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.GregorianCalendar;
import java.util.TimeZone;
import javax.swing.*;
public class Clock2d extends JPanel {
TimeZone clockTimeZone = TimeZone.getDefault();
GregorianCalendar cal =
(GregorianCalendar) GregorianCalendar.getInstance(clockTimeZone);
ActionListener repaintListener = (ActionEvent e) -> {
cal = (GregorianCalendar) GregorianCalendar.getInstance(clockTimeZone);
repaint();
};
Timer clockTimer = new Timer(100, repaintListener);
public Clock2d() {
clockTimer.start();
}
@Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
g.setColor(Color.BLUE);
g.fillOval(40, 40, 220, 220);
g.setColor(Color.WHITE);
g.fillOval(50, 50, 200, 200);
double second = cal.get(Calendar.SECOND);
double minute = cal.get(Calendar.MINUTE);
double hours = cal.get(Calendar.HOUR);
for (int i = 0; i < 60; i++) {
int length = 90;
double rad = (i * 6) * (Math.PI) / 180;
if (i % 5 == 0) {
length = 82;
g.setColor(Color.BLUE);
} else {
g.setColor(Color.GRAY);
}
int x = 150 + (int) (95 * Math.cos(rad - (Math.PI / 2)));
int y = 150 + (int) (95 * Math.sin(rad - (Math.PI / 2)));
int x1 = 150 + (int) (length * Math.cos(rad - (Math.PI / 2)));
int y1 = 150 + (int) (length * Math.sin(rad - (Math.PI / 2)));
g.drawLine(x, y, x1, y1);
}
drawHands(g, second, minute, hours);
SimpleDateFormat sdf = new SimpleDateFormat("hh:mm:ss");
g.setColor(Color.BLUE);
g.setFont(new Font("Tahoma", Font.BOLD, 16));
g.drawString(sdf.format(cal.getTime()), 120, 20);
g.setFont(new Font("Arial", Font.BOLD, 10));
}
public void drawHands(Graphics g, double second, double minute, double hours) {
double rSecond = (second * 6) * (Math.PI) / 180;
double rMinute = ((minute + (second / 60)) * 6) * (Math.PI) / 180;
double rHours = ((hours + (minute / 60)) * 30) * (Math.PI) / 180;
g.setColor(Color.RED);
g.drawLine(150, 150, 150 + (int) (100 * Math.cos(rSecond - (Math.PI / 2))), 150 + (int) (100 * Math.sin(rSecond - (Math.PI / 2))));
g.setColor(Color.BLACK);
g.drawLine(150, 150, 150 + (int) (70 * Math.cos(rMinute - (Math.PI / 2))), 150 + (int) (70 * Math.sin((rMinute - (Math.PI / 2)))));
g.drawLine(150, 150, 150 + (int) (50 * Math.cos(rHours - (Math.PI / 2))), 150 + (int) (50 * Math.sin(rHours - (Math.PI / 2))));
}
public static void main(String[] args) {
// Swing / AWT GUIs should be created & changed on the EDT ..
Runnable r = () -> {
JFrame frame = new JFrame("Clock 2D");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setPreferredSize(new Dimension(330, 330));
Clock2d clock2d = new Clock2d();
clock2d.setPreferredSize(new Dimension(320, 320));
frame.setLayout(new BorderLayout());
frame.getContentPane().add(clock2d, BorderLayout.CENTER);
frame.pack();
frame.setVisible(true);
};
// .. this is how we ensure that Runnable is on the EDT.
SwingUtilities.invokeLater(r);
}
}
關于字體的更多提示：
g.setFont(new Font("Arial", Font.BOLD, 10));
鑒于 Paint 方法被重復調用，最好在構造類時建立字體（兩者）并將它們存儲為類的屬性（可以在方法中引用）。
但最好使用邏輯字體而不是“Arial”之類的字體，如下所示：
g.setFont(new Font(Font.SANS_SERIF, Font.BOLD, 10));
這不僅提供編譯時檢查，而且可以跨操作系統平臺進行調整。例如，該SANS_SERIF字體在 Windows 上會生成 Arial，可能在大多數 *nix 盒子上，但在 OS X 上默認SANS_SERIF（未修飾的）字體是 Helvetica。
另一種字體 Tahoma 的問題更大。同樣，它可能出現在許多 Windows 機器上，但最好要么對其進行測試并擁有備份列表，要么在時鐘應用程序中提供字體。（假設您擁有發行權）。
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