如何解决Java“绘画”应用程序
我正在设计这个类似于绘画的 Java 程序，虽然它快完成了，但我需要一些帮助。我的问题是： 该程序应该能够使用剪贴板进行复制和粘贴。如您所见，我一直无法弄清楚如何使用剪贴板进行操作，所以我做了一个替代品，它不能 100% 正确运行。你能帮我处理剪贴板吗？ 我写的代码只显示 1 个复制的形状......但不显示很多形状...... 我已经尝试过 LinkedList、vector、ArrayList，但没有任何效果 请指教！
** 显示由形状组成的场景的组件。 **
import java.awt.*;
import javax.swing.*;
import java.util.*;
public class SceneComponent extends JPanel {
private final ArrayList<Sceneshape> shapes;
private Sceneshape copiedShape;
private ArrayList<Sceneshape> copiedShapesList;
public void add(Sceneshape s) {
shapes.add(s);
s.setSelected(false);
repaint();
}
public void copySelectedShapes() {
for (Sceneshape s : shapes) {
copiedShape = s.copy();
copiedShapesList.add(copiedShape);
System.out.println("shapes copied number === " + copiedShapesList.size());
}
}
public void pasteSelectedShapes() {
shapes.addAll(copiedShapesList);
System.out.println("shapes size === " + shapes.size());
repaint();
}
void selectAll() {
for (Sceneshape s : shapes) {
s.setSelected(true);
}
repaint();
}
public void removeSelected() {
shapes.removeIf(Sceneshape::isSelected);
repaint();
}
void deleteall() {
shapes.clear();
repaint();
}
public SceneComponent() {
shapes = new ArrayList<>();
copiedShapesList = new ArrayList<>();
setBackground(Color.white);
}
public void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2 = (Graphics2D) g;
for (Sceneshape s : shapes) {
s.draw(g2);
if (s.isSelected()) {
s.drawSelection(g2);
}
}
}
}
**
A house shape.
**
import java.awt.*;
import java.awt.geom.*;
/**
* A house shape.
*/
public class HouseShape extends SelectableShape {
private int x,y;
public HouseShape(int x,int y,int width) {
this.x = x;
this.y = y;
this.width = width;
}
public void draw(Graphics2D g2) {
Rectangle2D.Double base
= new Rectangle2D.Double(x,y + width,width,width);
// The left bottom of the roof
Point2D.Double r1
= new Point2D.Double(x,y + width);
// The top of the roof
Point2D.Double r2
= new Point2D.Double(x + width / 2,y);
// The right bottom of the roof
Point2D.Double r3
= new Point2D.Double(x + width,y + width);
Line2D.Double roofLeft
= new Line2D.Double(r1,r2);
Line2D.Double roofRight
= new Line2D.Double(r2,r3);
g2.draw(base);
g2.draw(roofLeft);
g2.draw(roofRight);
}
@Override
public void drawSelection(Graphics2D g2) {
Rectangle2D.Double base = new Rectangle2D.Double(x,width);
g2.fill(base);
}
public boolean contains(Point2D p) {
return x <= p.getX() && p.getX() <= x + width
&& y <= p.getY() && p.getY() <= y + 2 * width;
}
private final int width;
@Override
public Sceneshape copy() {
int i=10;i=i+20;
return new HouseShape(i,100,50);
}
}
/***
the main program
**/
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class SceneEditor {
public static void main(String[] args) {
int i = 0;
JFrame frame = new JFrame();
frame.setDefaultCloSEOperation(JFrame.EXIT_ON_CLOSE);
final SceneComponent scene = new SceneComponent();
JButton houseButton = new JButton("House");
houseButton.addActionListener(new ActionListener() {
int i = 0;
@Override
public void actionPerformed(ActionEvent event) {
scene.add(new HouseShape(i,50,50) {
});
i = i + 100;
}
});
JButton selectButton = new JButton("delete All");
selectButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent event) {
scene.deleteall();
}
});
JButton selectAllButton = new JButton("select All");
selectAllButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent event) {
scene.selectAll();
}
});
JButton copyButton = new JButton("copy");
selectAllButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent event) {
scene.copySelectedShapes();
}
});
JButton pasteButton = new JButton("Paste");
pasteButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent event) {
scene.pasteSelectedShapes();
}
});
JPanel buttons = new JPanel();
buttons.add(houseButton);
buttons.add(selectAllButton);
buttons.add(selectButton);
buttons.add(copyButton);
buttons.add(pasteButton);
frame.setBackground(Color.black);
frame.add(scene,BorderLayout.CENTER);
frame.add(buttons,BorderLayout.norTH);
frame.setSize(800,800);
frame.setLocation(300,100);
frame.setVisible(true);
}
}
the interface for the common methodes that must be implemented
import java.awt.*;
public interface Sceneshape
{
abstract Sceneshape copy();
void draw(Graphics2D g2);
void drawSelection(Graphics2D g2);
void setSelected(boolean b);
boolean isSelected();
}
import java.awt.*;
import java.awt.geom.*;
public class SelectableShape implements Sceneshape {
Rectangle2D rectangle;
Color color;
protected Point upperLeft;
public void setSelected(boolean b) {
selected = b;
}
public boolean isSelected() {
return selected;
}
private boolean selected = false;
@Override
public Sceneshape copy() {
throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods,choose Tools | Templates.
}
@Override
public void draw(Graphics2D g2) {
throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods,choose Tools | Templates.
}
@Override
public void drawSelection(Graphics2D g2) {
throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods,choose Tools | Templates.
}
}
解决方法
您的问题似乎是由创建按钮时的拼写错误引起的：
JButton copyButton = new JButton("Copy");
selectAllButton.addActionListener(new ActionListener() {
//...
注意您如何创建 copyButton，然后向 selectAllButton 添加动作侦听器。要解决此问题，您应该使用：
JButton copyButton = new JButton("Copy");
//Now creating an action listener for the correct button
copyButton.addActionListener(new ActionListener() {
//...
调试此类问题的一种方法是在每一步都将更多信息打印到控制台，例如下面的 te 将向我们展示从未调用过 copySelectedShapes 方法，并且向后工作您将能够找到上面的错字：
public void copySelectedShapes() {
//Ad print statement outside the loop so it works even if there are zero shapes
System.out.println("Copy method called for " + shapes.size() + "shapes");
for (SceneShape s : shapes) {
copiedShape = s.copy();
copiedShapesList.add(copiedShape);
//Print out the shape toString ID
System.out.println("Copied shape " + s.toString());
}
}
注意：在您的 SceneComponent 类中，您覆盖了 add 方法，但是，JPanel 类已经具有用于添加新 Swing 组件的默认 add 方法，您应该重命名您的add 方法 addShape 像这样：
//Method name changed to avoid issues
public void addShape(SceneShape s) {
shapes.add(s);
s.setSelected(false);
repaint();
}
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