JPanelのは、いわゆる「汚い」ピクセルを除去することを含むそのハウスキーピンググラフィックスを、行いますようにスーパーのメソッド最初のものを呼び出す必要がありますあなたのpaintComponentメソッド。だから、：
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g); // *** add this ***
g.setColor(color);
g.fillOval(100, 100, 100, 100);
}
私自身、私はあなたが考えるかすることはできませんいくつかの提案で、少し違ったものにしてください：
- を単に描画し、他には何のためにあるのJPanel、ノーボタンを作成し、いいえ、別に。
- JButtonを別のJPanelに配置します。
- ColorをStringと組み合わせ、ボタンを作成するときに使用するための、おそらくLightColorと呼ばれる列挙型を使用します。
- paintComponentメソッドでGraphicsオブジェクトをGraphics2Dオブジェクトにキャストし、RenderingHintsを使用して円滑な円を描くことができます。
- サイズを設定しないでください。その代わりに、必要に応じてsetPreferredSizeをオーバーライドし、アプリケーションのコンポーネントとレイアウトマネージャーを、JFrameを作成した後、表示する前に、
pack()を呼び出してサイズを変更します。たとえば、
：
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GridLayout;
import java.awt.RenderingHints;
import java.awt.event.ActionEvent;
import javax.swing.*;
// main GUI JPanel that holds the light drawing JPanel as well as the buttons
@SuppressWarnings("serial")
public class TrafficLightPanel2 extends JPanel {
private static final int LIGHT_SIZE = 200; // size of the circle
private static final int GAP = 10; // border gap around the jpanel
// the Jlight drawing JPanel that draws the circles
private LightDrawingPanel lightDrawingPanel = new LightDrawingPanel(null, LIGHT_SIZE);
public TrafficLightPanel2() {
// JPanel to hold the buttons, 1 row, variable number of columns, gap between buttons
JPanel buttonPanel = new JPanel(new GridLayout(1, 0, GAP, 0));
for (LightColor lightColor : LightColor.values()) {
// create each button within the loop, giving it an Action -- an ActionListener "on steroids"
buttonPanel.add(new JButton(new LightColorAction(lightColor, lightDrawingPanel)));
}
setBorder(BorderFactory.createEmptyBorder(GAP, GAP, GAP, GAP));
setLayout(new BorderLayout(GAP, GAP));
add(lightDrawingPanel, BorderLayout.CENTER); // add the light drawer to the center
add(buttonPanel, BorderLayout.PAGE_END); // and the buttons to the bottom
}
private static void createAndShowGui() {
TrafficLightPanel2 mainPanel = new TrafficLightPanel2();
JFrame frame = new JFrame("Traffic Light");
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
frame.getContentPane().add(mainPanel);
frame.pack(); // have layout managers do their thing
frame.setLocationRelativeTo(null); // center
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(() -> createAndShowGui());
}
}
// just acts as a class that connects a Color with a String
enum LightColor {
RED(Color.RED, "Red"), YELLOW(Color.YELLOW, "Yellow"), GREEN(Color.GREEN, "Green");
private LightColor(Color color, String text) {
this.color = color;
this.text = text;
}
private Color color;
private String text;
public Color getColor() {
return color;
}
public String getText() {
return text;
}
@Override
public String toString() {
return text;
}
}
// create a class that only draws the circle, and that's it
@SuppressWarnings("serial")
class LightDrawingPanel extends JPanel {
private Color color;
private int size;
public LightDrawingPanel(Color color, int size) {
this.color = color;
this.size = size;
}
public void setColor(Color color) {
this.color = color;
repaint();
}
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g); // again, the super must be called
// if no color defined, get out of here
if (color == null) {
return;
}
g.setColor(color);
// make for smooth rendering
Graphics2D g2 = (Graphics2D) g;
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
// center the circle
int x = (getWidth() - size)/2;
int y = (getHeight() - size)/2;
g2.fillOval(x, y, size, size);
}
// make our JPanel at least as large as the circle
@Override
public Dimension getPreferredSize() {
if (isPreferredSizeSet()) {
return super.getPreferredSize();
}
return new Dimension(size, size);
}
}
// AbstractAction for our buttons
// like an ActionListener "on steroids"
@SuppressWarnings("serial")
class LightColorAction extends AbstractAction {
private LightColor lightColor;
private LightDrawingPanel lightDrawingPanel;
public LightColorAction(LightColor lightColor, LightDrawingPanel lightDrawingPanel) {
super(lightColor.getText()); // text for the button to show
// initialize our fields
this.lightColor = lightColor;
this.lightDrawingPanel = lightDrawingPanel;
// alt-key mnemonic derived from the text String
int mnemonic = (int) lightColor.getText().charAt(0);
putValue(MNEMONIC_KEY, mnemonic);
}
@Override
public void actionPerformed(ActionEvent e) {
// set the color of the drawing panel
lightDrawingPanel.setColor(lightColor.getColor());
}
}
答えるように編集内容を参照してください。 –