绘制用户选择的形状 [英] Draw Shapes That User Selects
问题描述
我需要创建一个程序来绘制形状（用户使用单选按钮选择），以及是否填充形状（用户使用复选框选择）。这是我到目前为止的代码：
I need to create a program to draw shapes(user chooses with radio button), and whether or not the shape is filled(user chooses with check box). This is the code I have so far:
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class SelectShape extends JFrame implements ItemListener{
private JRadioButton line = new JRadioButton("Line");
private JRadioButton rect = new JRadioButton("Rectangle");
private JRadioButton oval = new JRadioButton("Oval");
private JCheckBox fill = new JCheckBox("Filled");
private FigurePanel fp;
public static void main(String[] args) {
SelectShape frame = new SelectShape();
frame.setTitle("Select Shape");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLocationRelativeTo(null);
frame.setSize(400,400);
frame.setVisible(true);
}
public SelectShape() {
JPanel p1 = new JPanel();
p1.add(fp);
fp.setBackground(Color.WHITE);
p1.setSize(200,400);
JPanel p2 = new JPanel();
p2.setLayout(new FlowLayout());
p2.add(line);
p2.add(rect);
p2.add(oval);
p2.add(fill);
add(p2, "South");
line.addItemListener(this);
rect.addItemListener(this);
oval.addItemListener(this);
fill.addItemListener(this);
}
public void ItemStateChanged(ItemEvent e) {
if(rect.isSelected()) {
FigurePanel.dRect();
repaint();
}
else if(oval.isSelected()) {
FigurePanel.dOval();
repaint();
}
else if(line.isSelected()) {
FigurePanel.dLine();
repaint();
}
if(fill.isSelected()) {
FigurePanel.fill();
repaint();
}
else {
FigurePanel.erase();
repaint();
}
}
}
class FigurePanel extends JPanel {
public void paintComponent(Graphics g) {
super.paintComponent(g);
public void dLine(Graphics g) {
g.drawLine(10,10,160,10);
}
public void dRect(Graphics g) {
g.drawRect(10,10,150,50);
}
public void dOval(Graphics g) {
g.drawOval(10,10,150,50);
}
public void fill(Graphics g) {
g.setColor(Color.GREEN);
if(rect.isSelected()) {
g.fillRect(10,10,150,50);
}
else if(oval.isSelected()) {
g.fillOval(10,10,150,50);
}
}
public void erase(Graphics g) {
g.setColor(Color.WHITE);
if(rect.isSelected()) {
g.fillRect(10,10,150,50);
}
else if(oval.isSelected()) {
g.fillOval(10,10,150,50);
}
}
}
}
我遇到的错误是表达式和标识符的非法开头。如果我应该采用其他方式，请告诉。
The errors I am getting are illegal start of expression and identifier expected. If I should approach this another way, please tell.
推荐答案
我认为您需要回到基础知识...
I think you need to go back to basics...
这不起作用...
fp.setBackground("white");
Component＃setBackground String 作为参数，它需要 Color
Component#setBackground doesn't take a String as a parameter, it takes a Color
您所有的 addItemListener 调用都不会起作用，因为您尚未实现 ItemListener
All your addItemListener calls arn't going to work, because you've not implement a ItemListener
我不确定您希望通过此操作实现什么...
I'm not sure what it is you hope to achieve by doing this...
@Override
fp.dRect();
但这是行不通的。 @Override用于指示某个方法已被祖先覆盖，您只是在调用 FigurePanel
But it won't work. @Override is used to indicate that a method was overridden by an ancestor, you are simply calling the method of FigurePanel
Java，像C和C ++一样，区分大小写；
Java, like C and C++ is case sensitive;
没有这样的类 itemEvent ...它是 ItemEvent
There is no such class itemEvent...it's ItemEvent
public void ItemStateChanged(itemEvent e) {
没有这样的类 graphics ，它是图形
public void paintComponent(graphics g) {
我什至不会尝试猜测您希望通过以下方式实现的目标...
And I'm not even going to try and guess what it is you were hoping to achieve with the following...
public void paintComponent(graphics g) {
super.paintComponent(g);
dLine() {
g.drawLine(10, 10, 160, 10);
}
dRect() {
g.drawRect(10, 10, 150, 50);
}
dOval() {
g.drawOval(10, 10, 150, 50);
}
fill() {
g.setColor(Color.GREEN);
if (rect.isSelected()) {
g.fillRect(10, 10, 150, 50);
} else if (oval.isSelected()) {
g.fillOval(10, 10, 150, 50);
}
}
erase() {
g.setColor(Color.WHITE);
if (rect.isSelected()) {
g.fillRect(10, 10, 150, 50);
} else if (oval.isSelected()) {
g.fillOval(10, 10, 150, 50);
}
}
}
Java不支持内联方法（或者您想要调用的方法），并且不会，使它们成为方法也不会实现您要尝试执行的操作...
Java doesn't support "inline methods" (or what ever you want to call them) and no, making them methods would also not achieve what you are trying to do...
实际上你做得很好的一件事是重写 paintComponent 并调用 super.paintComponent ...做得好：D！
In fact the one thing you did very well, was to override paintComponent and call super.paintComponent...well done :D !
已更新
我鼓励您通读...
- The Java路径，尤其是那些涉及基础知识的路径，尤其是那些涉及继承的路径
- 自定义绘画
- 2D图形
- The Java Trails, especially those covering the basics, especially those covering inheritance
- Custom Painting
- 2D Graphics
已更新了可能的运行示例
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.Shape;
import java.awt.event.ActionEvent;
import java.awt.geom.Ellipse2D;
import java.awt.geom.Line2D;
import java.awt.geom.Rectangle2D;
import javax.swing.AbstractAction;
import javax.swing.ButtonGroup;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JRadioButton;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class DrawShapes {
public static void main(String[] args) {
new DrawShapes();
}
public DrawShapes() {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new BorderLayout());
frame.add(new DrawPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class DrawPane extends JPanel {
public DrawPane() {
setLayout(new BorderLayout());
RenderPane rp = new RenderPane();
add(new ControlsPane(rp), BorderLayout.NORTH);
add(rp);
}
}
public class ControlsPane extends JPanel {
public ControlsPane(RenderPane rp) {
JRadioButton[] btns = new JRadioButton[4];
btns[0] = new JRadioButton(new LineAction(rp));
btns[1] = new JRadioButton(new RectangleAction(rp));
btns[2] = new JRadioButton(new OvalAction(rp));
btns[3] = new JRadioButton(new ClearAction(rp));
ButtonGroup bg = new ButtonGroup();
for (JRadioButton btn : btns) {
bg.add(btn);
add(btn);
}
}
}
public class RenderPane extends JPanel {
private Shape shape;
@Override
public Dimension getPreferredSize() {
return new Dimension(400, 400);
}
public void setShape(Shape shape) {
this.shape = shape;
repaint();
}
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
if (shape != null) {
g2d.setColor(Color.RED);
g2d.draw(shape);
}
g2d.dispose();
}
}
public class LineAction extends AbstractRenderAction {
public LineAction(RenderPane renderPane) {
super(renderPane);
putValue(NAME, "Line");
}
@Override
public Shape getShape() {
return new Line2D.Float(0f, 0f, getRenderPane().getWidth(), getRenderPane().getHeight());
}
}
public class RectangleAction extends AbstractRenderAction {
public RectangleAction(RenderPane renderPane) {
super(renderPane);
putValue(NAME, "Rectangle");
}
@Override
public Shape getShape() {
return new Rectangle2D.Float(10, 10, getRenderPane().getWidth() - 20, getRenderPane().getHeight() - 20);
}
}
public class OvalAction extends AbstractRenderAction {
public OvalAction(RenderPane renderPane) {
super(renderPane);
putValue(NAME, "Oval");
}
@Override
public Shape getShape() {
float radius = Math.min(getRenderPane().getWidth() - 20, getRenderPane().getHeight() - 20);
return new Ellipse2D.Float(10, 10, radius, radius);
}
}
public class ClearAction extends AbstractRenderAction {
public ClearAction(RenderPane renderPane) {
super(renderPane);
putValue(NAME, "Clear");
}
@Override
public Shape getShape() {
return null;
}
}
public abstract class AbstractRenderAction extends AbstractAction {
private RenderPane renderPane;
public AbstractRenderAction(RenderPane renderPane) {
this.renderPane = renderPane;
}
public RenderPane getRenderPane() {
return renderPane;
}
public abstract Shape getShape();
@Override
public void actionPerformed(ActionEvent e) {
getRenderPane().setShape(getShape());
}
}
}
这篇关于绘制用户选择的形状的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
