我正在制作一个绘制形状的程序。单击菜单中的形状后，它会根据 jSlider 中的值绘制下面的形状。
我正在尝试创建一个异常，以便当用户尝试将框架调整为小于 DrawPanel 上绘制的形状时。
为此，我想创建一个 if 语句，因此如果框架的宽度或高度小于 xy 位置加上滑块的值，它将引发异常。
绘图：
package ShapesProgram;
//adding the imports
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import javax.swing.JPanel;
/**
*
* @
*/
public class DrawShape extends JPanel {
//Declaring variables
private boolean isCircle;
private boolean isSquare;
private boolean isTriangle;
private int xPosition = 50;
private int yPosition = 50;
MyFrame shapeFrame;
int length;
//making the frame
public DrawShape(MyFrame f) {
shapeFrame = f;
initComponents();
isCircle = false;
isSquare = false;
isTriangle = false;
this.setBackground(Color.LIGHT_GRAY);
repaint();
}
public void setLength(int length) {
this.length = length;
}
//setting the shapes to false
public void setIsCircle(boolean isCircle) {
this.isCircle = isCircle;
this.isSquare = false;
this.isTriangle = false;
}
public void setIsSquare(boolean isSquare) {
this.isSquare = isSquare;
this.isCircle = false;
this.isTriangle = false;
}
public void setIsTriangle(boolean isTriangle) {
this.isTriangle = isTriangle;
this.isSquare = false;
this.isCircle = false;
}
@Override
public void paintComponent(Graphics g) {
Graphics2D g2 = (Graphics2D) g;
super.paintComponent(g);
if (isSquare == true) {
// draw a Square
g2.drawRect(xPosition, yPosition, length, length);
repaint();
} else if (isCircle == true) {
// draw a Circle
g2.drawOval(xPosition, yPosition, length, length);
repaint();
} else if (isTriangle == true) {
// draw a Trianlge
int[] xPoints = new int[3];
int[] yPoints = new int[3];
xPoints[0] = xPosition;
xPoints[1] = xPoints[0];
xPoints[2] = xPoints[1] + length;
yPoints[0] = yPosition;
yPoints[1] = yPoints[0] + length;
yPoints[2] = yPoints[1];
g2.drawPolyline(xPoints, yPoints, xPoints.length);
g2.drawLine(xPoints[0], yPoints[0], xPoints[2], yPoints[2]);
repaint();
}
}
/**
* This method is called from within the constructor to initialize the form.
* WARNING: Do NOT modify this code. The content of this method is always
* regenerated by the Form Editor.
*/
@SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">
private void initComponents() {
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(this);
this.setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGap(0, 400, Short.MAX_VALUE)
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGap(0, 300, Short.MAX_VALUE)
);
}// </editor-fold>
// Variables declaration - do not modify
// End of variables declaration
}
我的控制面板：
package ShapesProgram;
//adding the imports
import java.awt.Color;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.text.DecimalFormat;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JSlider;
import javax.swing.JTextField;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;
/**
*
* @
*/
public class MyControlPanel extends JPanel {
//making a new slider
private ChangeListener sliderAction = new MyChangeAction();
JSlider thejSlider = new JSlider(0, 100);
//creating the labels for Boundary Length, Slider and Area
JLabel lblLenght = new JLabel("Boundary Length");
JLabel lblSlider = new JLabel("Slider");
JLabel lblArea = new JLabel("Area");
//creating the textFields for the Area and Boundary Lengrth
JTextField txtArea = new JTextField(8);
JTextField txtBLength = new JTextField(8);
MyFrame MyControlPanelFrame;
//Constraints required for GridBagLayout
GridBagConstraints gbc = new GridBagConstraints();
public MyControlPanel(MyFrame f) {
MyControlPanelFrame = f;
initComponents();
//setting background color and layout for the frame
this.setBackground(Color.gray);
this.setLayout(new GridBagLayout());
//setting up slider and adding it to the frame
thejSlider.setMajorTickSpacing(10);
thejSlider.setPaintLabels(true);
thejSlider.setPaintTicks(true);
gbc.gridx = 14;
gbc.gridy = 11;
this.add(thejSlider, gbc);
//addig the label for the slider to the frame
this.add(lblSlider, gbc);
gbc.gridx = 4;
gbc.gridy = 11;
//adding the label for the area to the frame
this.add(lblArea, gbc);
gbc.gridx = 10;
gbc.gridy = 11;
//adding the textField for area to the frame
this.add(txtArea, gbc);
gbc.gridx = 2;
gbc.gridy = 10;
gbc.gridwidth = 4;
//adding the label for boundary length to the frame
this.add(lblLenght, gbc);
gbc.gridx = 10;
gbc.gridy = 10;
//adding the textField for boundary length to the frame
this.add(txtBLength, gbc);
gbc.gridx = 14;
gbc.gridy = 10;
linkEventHandler();
}
//creating the event handler for the slider action
public void linkEventHandler() {
thejSlider.addChangeListener(sliderAction);
}
class MyChangeAction implements ChangeListener {
@Override
public void stateChanged(ChangeEvent e) {
//obtain jslider value
int currentValue = thejSlider.getValue();
//passing the value of the slider to the draw panel
MyControlPanelFrame.getDrawPanel().setLength(currentValue);
//setting the format for the numbers
DecimalFormat df = new DecimalFormat("0.0");
//obtain the shape
//calculate Area
double x = MyControlPanelFrame.getMyShape().computeArea(currentValue);
//display area
txtArea.setText(df.format(x));
//obtain the shape
//calculate boundary length
double y = MyControlPanelFrame.getMyShape().computeBLength(currentValue);
//display boundary length
txtBLength.setText(df.format(y));
//repaint the shape
MyControlPanelFrame.getDrawPanel().repaint();
}
}
/**
* This method is called from within the constructor to initialize the form.
* WARNING: Do NOT modify this code. The content of this method is always
* regenerated by the Form Editor.
*/
@SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">
private void initComponents() {
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(this);
this.setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGap(0, 400, Short.MAX_VALUE)
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGap(0, 300, Short.MAX_VALUE)
);
}// </editor-fold>
// Variables declaration - do not modify
// End of variables declaration
}
我的框架：
package ShapesProgram;
//adding the imports
import MyShape.Circle;
import MyShape.MyShape;
import MyShape.Square;
import MyShape.Triangle;
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.text.DecimalFormat;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
/**
*
* @
*/
public final class MyFrame extends javax.swing.JFrame {
MyShape myShape = new MyShape();
//creating a new JMenuBar
JMenuBar jMenuBar1 = new JMenuBar();
JMenu shape = new JMenu("Shape");
//creating new JMenuItems dor the shapes
JMenuItem circle = new JMenuItem("Circle");
JMenuItem square = new JMenuItem("Square");
JMenuItem triangle = new JMenuItem("Triangle");
MyControlPanel panel1 = new MyControlPanel(this);
DrawShape drawPanel = new DrawShape(this);
//Creates new form MyFrame
public MyFrame() {
//setting the size, title and minimum size of the frame
this.setSize(400, 400);
this.setMinimumSize(new Dimension(400, 400));
this.setTitle("Shapes Program");
initComponents();
linkListeners();
//setting the layout for the frame
this.setLayout(new BorderLayout());
//adding the components to the frame
shape.add(square);
shape.add(circle);
shape.add(triangle);
jMenuBar1.add(shape);
setJMenuBar(jMenuBar1);
//adding the panels to the frame
this.add(panel1, BorderLayout.SOUTH);
this.add(drawPanel, BorderLayout.CENTER);
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
}
//creating a new action listener for the shapes
public void linkListeners() {
MyActionListener l = new MyActionListener();
circle.addActionListener(l);
square.addActionListener(l);
triangle.addActionListener(l);
}
class MyActionListener implements ActionListener {
@Override
public void actionPerformed(ActionEvent e) {
Object obj = e.getSource();
//when square is selected, it is set to visable
//and outputs "Square Selected
if ((JMenuItem) obj == square) {
myShape = new Square();
drawPanel.setIsSquare(true);
System.out.println("Square Selected");
//when circle is selected, it is set to visable
//and outputs "Circle Selected
} else if ((JMenuItem) obj == circle) {
myShape = new Circle();
drawPanel.setIsCircle(true);
System.out.println("Circle Selected");
}
//when triangle is selected, it is set to visable
//and outputs "Triangle Selected
else if ((JMenuItem) obj == triangle) {
myShape = new Triangle();
drawPanel.setIsTriangle(true);
System.out.println("Triangle Selected");
}
}
}
public DrawShape getDrawPanel() {
return drawPanel;
}
public MyShape getMyShape() {
return myShape;
}
/**
* This method is called from within the constructor to initialize the form.
* WARNING: Do NOT modify this code. The content of this method is always
* regenerated by the Form Editor.
*/
@SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">
private void initComponents() {
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGap(0, 400, Short.MAX_VALUE)
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGap(0, 300, Short.MAX_VALUE)
);
pack();
}// </editor-fold>
/**
* @param args the command line arguments
*/
public static void main(String args[]) {
/* Set the Nimbus look and feel */
//<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
/* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
* For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html
*/
try {
for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
if ("Nimbus".equals(info.getName())) {
javax.swing.UIManager.setLookAndFeel(info.getClassName());
break;
}
}
} catch (ClassNotFoundException ex) {
java.util.logging.Logger.getLogger(MyFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (InstantiationException ex) {
java.util.logging.Logger.getLogger(MyFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (IllegalAccessException ex) {
java.util.logging.Logger.getLogger(MyFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (javax.swing.UnsupportedLookAndFeelException ex) {
java.util.logging.Logger.getLogger(MyFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
}
//</editor-fold>
/* Create and display the form */
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
new MyFrame().setVisible(true);
DecimalFormat oneDigit = new DecimalFormat("#,##0.0");
}
});
}
// Variables declaration - do not modify
// End of variables declaration
}
我的框架：
package ShapesProgram;
//adding the imports
import MyShape.Circle;
import MyShape.MyShape;
import MyShape.Square;
import MyShape.Triangle;
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.text.DecimalFormat;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
/**
*
* @
*/
public final class MyFrame extends javax.swing.JFrame {
MyShape myShape = new MyShape();
//creating a new JMenuBar
JMenuBar jMenuBar1 = new JMenuBar();
JMenu shape = new JMenu("Shape");
//creating new JMenuItems dor the shapes
JMenuItem circle = new JMenuItem("Circle");
JMenuItem square = new JMenuItem("Square");
JMenuItem triangle = new JMenuItem("Triangle");
MyControlPanel panel1 = new MyControlPanel(this);
DrawShape drawPanel = new DrawShape(this);
//Creates new form MyFrame
public MyFrame() {
//setting the size, title and minimum size of the frame
this.setSize(400, 400);
this.setMinimumSize(new Dimension(400, 400));
this.setTitle("Shapes Program");
initComponents();
linkListeners();
//setting the layout for the frame
this.setLayout(new BorderLayout());
//adding the components to the frame
shape.add(square);
shape.add(circle);
shape.add(triangle);
jMenuBar1.add(shape);
setJMenuBar(jMenuBar1);
//adding the panels to the frame
this.add(panel1, BorderLayout.SOUTH);
this.add(drawPanel, BorderLayout.CENTER);
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
}
//creating a new action listener for the shapes
public void linkListeners() {
MyActionListener l = new MyActionListener();
circle.addActionListener(l);
square.addActionListener(l);
triangle.addActionListener(l);
}
class MyActionListener implements ActionListener {
@Override
public void actionPerformed(ActionEvent e) {
Object obj = e.getSource();
//when square is selected, it is set to visable
//and outputs "Square Selected
if ((JMenuItem) obj == square) {
myShape = new Square();
drawPanel.setIsSquare(true);
System.out.println("Square Selected");
//when circle is selected, it is set to visable
//and outputs "Circle Selected
} else if ((JMenuItem) obj == circle) {
myShape = new Circle();
drawPanel.setIsCircle(true);
System.out.println("Circle Selected");
}
//when triangle is selected, it is set to visable
//and outputs "Triangle Selected
else if ((JMenuItem) obj == triangle) {
myShape = new Triangle();
drawPanel.setIsTriangle(true);
System.out.println("Triangle Selected");
}
}
}
public DrawShape getDrawPanel() {
return drawPanel;
}
public MyShape getMyShape() {
return myShape;
}
/**
* This method is called from within the constructor to initialize the form.
* WARNING: Do NOT modify this code. The content of this method is always
* regenerated by the Form Editor.
*/
@SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">
private void initComponents() {
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGap(0, 400, Short.MAX_VALUE)
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGap(0, 300, Short.MAX_VALUE)
);
pack();
}// </editor-fold>
/**
* @param args the command line arguments
*/
public static void main(String args[]) {
/* Set the Nimbus look and feel */
//<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
/* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
* For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html
*/
try {
for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
if ("Nimbus".equals(info.getName())) {
javax.swing.UIManager.setLookAndFeel(info.getClassName());
break;
}
}
} catch (ClassNotFoundException ex) {
java.util.logging.Logger.getLogger(MyFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (InstantiationException ex) {
java.util.logging.Logger.getLogger(MyFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (IllegalAccessException ex) {
java.util.logging.Logger.getLogger(MyFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (javax.swing.UnsupportedLookAndFeelException ex) {
java.util.logging.Logger.getLogger(MyFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
}
//</editor-fold>
/* Create and display the form */
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
new MyFrame().setVisible(true);
DecimalFormat oneDigit = new DecimalFormat("#,##0.0");
}
});
}
// Variables declaration - do not modify
// End of variables declaration
}
圆圈：
package MyShape;
/**
*
* @
*/
public class Circle extends MyShape {
@Override
public double computeArea(int length) {
return length*length*Math.PI;
}
@Override
public double computeBLength(int length) {
return 2*length*Math.PI;
}
}
正方形：
package MyShape;
/**
*
* @
*/
public class Square extends MyShape {
@Override
public double computeArea(int length) {
return length*length;
}
@Override
public double computeBLength(int length) {
return 4*length;
}
}
三角形：
package MyShape;
/**
*
* @
*/
public class Triangle extends MyShape {
@Override
public double computeArea(int length) {
return length * 2 + Math.sqrt (2 * length * length);
}
@Override
public double computeBLength(int length) {
return length * length / 2;
}
}