- 你从来没有真正添加
C2F
任何能够绘制它的东西,因此你的paint
方法永远不会被调用。
- 你应该覆盖
paintComponent
代替paint
,因为您已经破坏了组件的油漆链,这可能会导致无穷无尽的问题,带来美妙而有趣的油漆故障。公约还建议您致电super.paintComponent
(当覆盖paintComponent
)以及在进行任何定制绘画之前
See 在 AWT 和 Swing 中绘画 http://www.oracle.com/technetwork/java/painting-140037.html and 进行定制绘画 http://docs.oracle.com/javase/tutorial/uiswing/painting/更多细节
作为一般建议,我不鼓励您在另一个组件的构造函数中创建框架,这将使该组件几乎再次无法使用(例如,如果您想在另一个容器上重复使用它)
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class C2F extends JComponent {
public C2F() {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
JFrame frame = new JFrame("Testing");
TestPane center = new TestPane();
JPanel top = new JPanel();
JPanel east = new JPanel();
JPanel south = new JPanel();
//give specific location
JLabel L1 = new JLabel("Please input Celcius or Fahrenheit to Convert");
top.add(L1);
JLabel l1 = new JLabel("Cel -> Fah");
south.add(l1);
JTextField T1 = new JTextField(12);
south.add(T1);
JButton B1 = new JButton("Convert");
south.add(B1);
JLabel l2 = new JLabel("Fah -> Cel");
south.add(l2);
JTextField T2 = new JTextField(12);
south.add(T2);
JButton B2 = new JButton("Convert");
south.add(B2);
//to create buttons and labels to give an answer
B1.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
double input1 = Double.parseDouble(T1.getText());
double output1 = input1 * (9 / 5) + 32;
T2.setText("" + output1);
center.setOutput1(output1);
}
});
B2.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
double input2 = Double.parseDouble(T2.getText());
double output2 = (input2 - 32) / 9 * 5;
T1.setText("" + output2);
center.setOutput2(output2);
}
});
//making events
frame.getContentPane().add(top, BorderLayout.NORTH);
frame.getContentPane().add(center, BorderLayout.CENTER);
frame.getContentPane().add(south, BorderLayout.SOUTH);
frame.getContentPane().add(east, BorderLayout.EAST);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
private double output1, output2;
public TestPane() {
}
@Override
public Dimension getPreferredSize() {
return new Dimension(200, 600);
}
public void setOutput1(double output1) {
this.output1 = output1;
repaint();
}
public void setOutput2(double output2) {
this.output2 = output2;
repaint();
}
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g;
g2d.setColor(Color.BLACK);
g2d.drawOval(350, 500, 12, 12);
g2d.setColor(Color.RED);
g2d.fillRect(350, 0, 10, (int) output1);
g2d.fillOval(350, 0, 10, 10);
g2d.setColor(Color.BLUE);
g2d.fillRect(350, 0, 10, (int) output2);
g2d.fillOval(350, 0, 10, 10);
g2d.dispose();
}
}
public static void main(String[] args) {//to run the program
new C2F();
}
}