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我的问题是,在哪里说“triangle.addActionListener(new ShapeAction());” 在我的代码中有一个错误说找不到 ShapeAction 符号,我在这里做错了什么?有人可以看看我的 If 语句,它的任务是:一旦单击菜单项,它就会从另一个类创建该形状的实例

public class MyFrame extends javax.swing.JFrame {
    public MyFrame() {
        // Create the menu
        JMenuBar topMenu = new JMenuBar();
        this.setJMenuBar(topMenu);

        //create the menu button "shapes"
        JMenu shapes = new JMenu("Shapes");
        topMenu.add(shapes);
        //Create the 3 shapes for the menu
        JMenuItem square = new JMenuItem("Square");
        square.addActionListener(new ShapeAction());

        JMenuItem circle = new JMenuItem("Circle");      
        circle.addActionListener(new ShapeAction());

        JMenuItem triangle = new JMenuItem("Triangle");
        triangle.addActionListener(new ShapeAction());

        //add shapes to menu
        shapes.add(circle);
        shapes.add(triangle);
        shapes.add(square);

        //add the menu
        setJMenuBar(topMenu);


        MyControlPanel pane = new MyControlPanel();
        getContentPane().add(pane);

        this.add(pane);
    }

    /**
     * @param args the command line arguments
     */
    public static void main(String args[]) {
        // <snip>

        /* Create and display the form */
        java.awt.EventQueue.invokeLater(new Runnable() {
                public void run() {
                new MyFrame().setVisible(true);
                }
                });

        class ShapeAction implements ActionListener{
            public void actionPerformed(ActionEvent e){
                JMenuItem clickedMenu = (JMenuItem)e.getSource();

                if (clickedMenu.getText().equals("Square")){
                    //implement abstract methods                
                    MyShape aSquare = new ASquare();

                }
                else if (clickedMenu.getText().equals("Circle")){ 
                    //implement abstract methods
                    MyShape ACircle = new ACircle();

                }
                else if (clickedMenu.getText().equals("Triangle")){ 
                    //implement abstract methods
                    MyShape ATriangle = new ATriangle();

                }
            }          
        }
    }

package assignment;

//import java.awt.FlowLayout;
import java.awt.BorderLayout;
import java.awt.FlowLayout;
import javax.swing.GroupLayout;
import javax.swing.GroupLayout.Alignment;
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 javax.swing.JPanel {

JSlider slider;
JLabel sliderLabel;
JLabel sliderdimension;
JLabel blank;
JLabel dl;
JLabel area1;

/**
 * Creates new form MyControlPanel
 */
public MyControlPanel() {


    slider = new JSlider();
    slider.setValue(50);
    slider.addChangeListener(new MyChangeAction());
    slider.setMajorTickSpacing(10);
    slider.setPaintLabels(true);
    slider.setPaintTicks(true);
    slider.setBounds(300, 50, 100, 50);

    sliderLabel = new JLabel("50");
    blank = new JLabel("     ");
    sliderdimension = new JLabel("Shape Dimension:");

    JTextField boundary_length = new JTextField("Boundary Length");
    JTextField area = new JTextField("Area");

    dl = new JLabel("Boundary Length =");
    area1 = new JLabel("Area =");

    setLayout(new BorderLayout());


    JPanel sliderPanel = new JPanel();
    sliderPanel.setLayout(new FlowLayout(FlowLayout.CENTER, 10, 0));


    sliderPanel.add(sliderdimension);
    sliderPanel.add(sliderLabel);
    sliderPanel.add(slider);
    sliderPanel.add(dl);
    sliderPanel.add(boundary_length);
    sliderPanel.add(area1);
    sliderPanel.add(area);
    this.add(sliderPanel, BorderLayout.PAGE_END);



}

/**
 * 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.
 */
// <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                   

public class MyChangeAction implements ChangeListener {

    //complete code here
    public void stateChanged(ChangeEvent ce) {
        int value = slider.getValue();
        String str = Integer.toString(value);
        sliderLabel.setText(str);


    }
} // end class




    }

package assignment;

public abstract class MyShape
 {

double thelength;
double thearea;



public abstract double computeBoundaryLength(double Length);

public abstract double computeArea (double Length);
 }

package assignment;


public class ACircle extends MyShape {

@Override
public double computeBoundaryLength(double Length) 
{
    thelength=(2*Length*Math.PI);
return thelength;
}

@Override
public double computeArea(double Length) 
{
    thearea=(Length*Length*Math.PI);
    return thearea;
}

}
4

1 回答 1

3

ShapeAction您应该在main方法之外,在类内部引入内部MyFrame类。你创建一个 localmain的方法类而不是那个。

只需将其移到main方法之外:

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;


public class MyFrame extends javax.swing.JFrame
{
    public MyFrame ()
    {
        // Create the menu
        JMenuBar topMenu = new JMenuBar ();
        this.setJMenuBar ( topMenu );

        //create the menu button "shapes"
        JMenu shapes = new JMenu ( "Shapes" );
        topMenu.add ( shapes );
        //Create the 3 shapes for the menu
        JMenuItem square = new JMenuItem ( "Square" );
        square.addActionListener ( new ShapeAction () );

        JMenuItem circle = new JMenuItem ( "Circle" );
        circle.addActionListener ( new ShapeAction () );

        JMenuItem triangle = new JMenuItem ( "Triangle" );
        triangle.addActionListener ( new ShapeAction () );

        //add shapes to menu
        shapes.add ( circle );
        shapes.add ( triangle );
        shapes.add ( square );

        //add the menu
        setJMenuBar ( topMenu );


        MyControlPanel pane = new MyControlPanel ();
        getContentPane ().add ( pane );

        this.add ( pane );
    }


    @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 );
            }
        } );
    }

    class ShapeAction implements ActionListener
    {
        public void actionPerformed ( ActionEvent e )
        {
            JMenuItem clickedMenu = ( JMenuItem ) e.getSource ();

            if ( clickedMenu.getText ().equals ( "Square" ) )
            {
                //implement abstract methods
                MyShape aSquare = new ASquare ();

            }
            else if ( clickedMenu.getText ().equals ( "Circle" ) )
            {
                //implement abstract methods
                MyShape ACircle = new ACircle ();

            }
            else if ( clickedMenu.getText ().equals ( "Triangle" ) )
            {
                //implement abstract methods
                MyShape ATriangle = new ATriangle ();

            }
        }
    }
}

PS 而且您在代码末尾忘记了一个右括号。我通过...在示例中添加了它

于 2012-10-24T14:40:52.587 回答