我可以通过按下JButton从扩展类中调用方法吗？ 我知道在按下JButton时如何显示消息等，但是我想知道是否可以这样做？
我想从Activate_and_Deactivate类调用方法，以用作通过按下单选按钮ON和OF来执行的操作。我可以将语句直接放在actionevent参数中，但是老师说我必须至少使用继承。
这是我的代码。
package Calculators;
import java.awt.EventQueue;
import javax.swing.JFrame;
import javax.swing.JTextField;
import javax.swing.JButton;
import java.awt.Font;
import java.awt.Button;
import java.awt.Color;
import javax.swing.JLabel;
import com.jgoodies.forms.factories.DefaultComponentFactory;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import javax.swing.SwingConstants;
import javax.swing.UIManager;
import javax.swing.border.EtchedBorder;
import javax.swing.border.CompoundBorder;
import javax.swing.JRadioButton;
public class UIFrame {
Activate_and_Deactivate act = new Activate_and_Deactivate();
JButton button0 = new JButton("0");
JButton button2 = new JButton("2");
JButton button1 = new JButton("1");
JButton button3 = new JButton("3");
JButton button4 = new JButton("4");
JButton button5 = new JButton("5");
JButton button6 = new JButton("6");
JButton button7 = new JButton("7");
JButton button8 = new JButton("8");
JButton button9 = new JButton("9");
JButton button_Div = new JButton("/");
JButton button_C = new JButton("C");
JButton button_Mul = new JButton("*");
JButton button_Add = new JButton("+");
JButton button_Sub = new JButton("-");
JButton button_Dot = new JButton(".");
JButton button_rec = new JButton("1/x");
JButton button_Sqr = new JButton("\u221A");
JButton button_neg = new JButton("±");
JButton button_per = new JButton("%");
JButton button_equal = new JButton("=");
JButton button_undo = new JButton("\u2190");
JButton btnExit = new JButton("exit");
JRadioButton rdbtnOn = new JRadioButton("On");
JRadioButton rdbtnOff = new JRadioButton("Off");
private JFrame frmCalculator;
private JTextField screen;
private JTextField value1;
private JTextField value2;
private JLabel operation;
double fNumber = 0;
double sNumber = 0;
double result = 0;
String ope;
String answer;
public static void main(String[] args) {
try
{
UIManager.setLookAndFeel(UIManager.getCrossPlatformLookAndFeelClassName());
UIManager.setLookAndFeel("com.sun.java.swing.plaf.nimbus.NimbusLookAndFeel"); //Motif, and Windows packages that it requires are shipped with the Java SDK this way
}
catch(Exception e){}
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
UIFrame window = new UIFrame();
window.frmCalculator.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
/**
* Create the application.
*/
public UIFrame() {
initialize();
}
/**
* Initialize the contents of the frame.
*/
private void initialize() {
frmCalculator = new JFrame();
frmCalculator.setTitle("Java calculator ver 3.1.6 by Muhammad Haroon");
frmCalculator.getContentPane().setBackground(new Color(0, 0, 0));
frmCalculator.getContentPane().setForeground(Color.DARK_GRAY);
frmCalculator.setBounds(100, 100, 326, 422);
frmCalculator.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frmCalculator.getContentPane().setLayout(null);
value1 = new JTextField();
value1.setForeground(Color.DARK_GRAY);
value1.setFont(new Font("Tahoma", Font.PLAIN, 19));
value1.setHorizontalAlignment(SwingConstants.RIGHT);
value1.setBorder(null);
value1.setBounds(151, 52, 141, 31);
frmCalculator.getContentPane().add(value1);
value1.setColumns(10);
value2 = new JTextField();
value2.setFont(new Font("Tahoma", Font.PLAIN, 24));
value2.setHorizontalAlignment(SwingConstants.RIGHT);
value2.setBorder(null);
value2.setBounds(71, 90, 218, 37);
frmCalculator.getContentPane().add(value2);
value2.setColumns(10);
operation = new JLabel("");
operation.setForeground(new Color(144, 238, 144));
operation.setHorizontalAlignment(SwingConstants.LEFT);
operation.setFont(new Font("Tahoma", Font.PLAIN, 20));
operation.setBounds(20, 97, 50, 31);
frmCalculator.getContentPane().add(operation);
screen = new JTextField();
screen.setBorder(new CompoundBorder(new EtchedBorder(EtchedBorder.RAISED, null, null), new EtchedBorder(EtchedBorder.LOWERED, null, null)));
screen.setEditable(false);
screen.setHorizontalAlignment(SwingConstants.RIGHT);
screen.setBounds(10, 48, 289, 82);
frmCalculator.getContentPane().add(screen);
screen.setColumns(10);
rdbtnOn.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
act.activate();
}
});
rdbtnOn.setFont(new Font("Cambria Math", Font.PLAIN, 12));
rdbtnOn.setForeground(new Color(255, 255, 255));
rdbtnOn.setBounds(11, 18, 38, 23);
frmCalculator.getContentPane().add(rdbtnOn);
rdbtnOff.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
act.deactivate();
}
});
rdbtnOff.setFont(new Font("Cambria Math", Font.PLAIN, 12));
rdbtnOff.setForeground(new Color(255, 255, 255));
rdbtnOff.setBounds(51, 18, 38, 23);
frmCalculator.getContentPane().add(rdbtnOff);
button0.setBackground(new Color(135, 206, 250));
button0.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
String num = value2.getText() + button0.getText(); //value.setText(value.getText()+Button)
value2.setText(num);
}
});
button0.setFont(new Font("Cambria Math", Font.PLAIN, 18));
button0.setBounds(11, 306, 110, 31);
frmCalculator.getContentPane().add(button0);
button2.setBackground(new Color(135, 206, 250));
button2.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
String num = value2.getText() + button2.getText(); //value.setText(value.getText()+Button)
value2.setText(num);
}
});
button1.setBackground(new Color(135, 206, 250));
button1.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
String num = value2.getText() + button1.getText(); //value.setText(value.getText()+Button)
value2.setText(num);
}
});
button1.setFont(new Font("Cambria Math", Font.PLAIN, 18));
button1.setBounds(11, 264, 50, 31);
frmCalculator.getContentPane().add(button1);
button2.setFont(new Font("Cambria Math", Font.PLAIN, 18));
button2.setBounds(71, 264, 50, 31);
frmCalculator.getContentPane().add(button2);
button3.setBackground(new Color(135, 206, 250));
button3.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
String num = value2.getText() + button3.getText(); //value.setText(value.getText()+Button)
value2.setText(num);
}
});
button3.setFont(new Font("Cambria Math", Font.PLAIN, 18));
button3.setBounds(131, 264, 50, 31);
frmCalculator.getContentPane().add(button3);
button4.setBackground(new Color(135, 206, 250));
button4.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
String num = value2.getText() + button4.getText(); //value.setText(value.getText()+Button)
value2.setText(num);
}
});
button4.setFont(new Font("Cambria Math", Font.PLAIN, 18));
button4.setBounds(11, 222, 50, 31);
frmCalculator.getContentPane().add(button4);
button5.setBackground(new Color(135, 206, 250));
button5.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
String num = value2.getText() + button5.getText(); //value.setText(value.getText()+Button)
value2.setText(num);
}
});
button5.setFont(new Font("Cambria Math", Font.PLAIN, 18));
button5.setBounds(71, 222, 50, 31);
frmCalculator.getContentPane().add(button5);
button6.setBackground(new Color(135, 206, 250));
button6.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
String num = value2.getText() + button6.getText(); //value.setText(value.getText()+Button)
value2.setText(num);
}
});
button6.setFont(new Font("Cambria Math", Font.PLAIN, 18));
button6.setBounds(131, 222, 50, 31);
frmCalculator.getContentPane().add(button6);
button7.setBackground(new Color(135, 206, 250));
button7.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
String num = value2.getText() + button7.getText(); //value.setText(value.getText()+Button)
value2.setText(num);
}
});
button7.setFont(new Font("Cambria Math", Font.PLAIN, 18));
button7.setBounds(11, 180, 50, 31);
frmCalculator.getContentPane().add(button7);
button8.setBackground(new Color(135, 206, 250));
button8.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
String num = value2.getText() + button8.getText(); //value.setText(value.getText()+Button)
value2.setText(num);
}
});
button8.setFont(new Font("Cambria Math", Font.PLAIN, 18));
button8.setBounds(71, 180, 50, 31);
frmCalculator.getContentPane().add(button8);
button9.setBackground(new Color(135, 206, 250));
button9.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
String num = value2.getText() + button9.getText(); //value.setText(value.getText()+Button)
value2.setText(num);
}
});
button9.setFont(new Font("Cambria Math", Font.PLAIN, 18));
button9.setBounds(131, 180, 50, 31);
frmCalculator.getContentPane().add(button9);
button_Div.setBackground(new Color(192, 192, 192));
button_Div.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
value1.setText(value2.getText());
operation.setText("/");
value2.setText(null);
}
});
button_C.setBackground(new Color(60, 179, 113));
button_C.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
value2.setText(null);
value1.setText(null);
operation.setText(null);
}
});
button_C.setFont(new Font("Cambria Math", Font.PLAIN, 18));
button_C.setBounds(71, 138, 50, 31);
frmCalculator.getContentPane().add(button_C);
button_Div.setFont(new Font("Cambria Math", Font.PLAIN, 18));
button_Div.setBounds(191, 180, 50, 31);
frmCalculator.getContentPane().add(button_Div);
button_Mul.setBackground(new Color(192, 192, 192));
button_Mul.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
value1.setText(value2.getText());
operation.setText("*");
value2.setText(null);
}
});
button_Mul.setFont(new Font("Cambria Math", Font.PLAIN, 18));
button_Mul.setBounds(191, 222, 50, 31);
frmCalculator.getContentPane().add(button_Mul);
button_Add.setBackground(new Color(192, 192, 192));
button_Add.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
value1.setText(value2.getText());
operation.setText("+");
ope = "+";
value2.setText(null);
}
});
button_Add.setFont(new Font("Cambria Math", Font.PLAIN, 18));
button_Add.setBounds(191, 306, 50, 31);
frmCalculator.getContentPane().add(button_Add);
button_Sub.setBackground(new Color(192, 192, 192));
button_Sub.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
value1.setText(value2.getText());
operation.setText("-");
value2.setText(null);
}
});
button_Sub.setFont(new Font("Cambria Math", Font.PLAIN, 18));
button_Sub.setBounds(191, 264, 50, 31);
frmCalculator.getContentPane().add(button_Sub);
button_Dot.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
String num = value2.getText() + button_Dot.getText(); //value.setText(value.getText()+Button)
value2.setText(num);
}
});
button_Dot.setFont(new Font("Cambria Math", Font.PLAIN, 18));
button_Dot.setBounds(131, 306, 50, 31);
frmCalculator.getContentPane().add(button_Dot);
button_rec.setBackground(new Color(192, 192, 192));
button_rec.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
double ops1 = Double.parseDouble(String.valueOf(value2.getText()));
double ops2 = Double.parseDouble(String.valueOf(value2.getText()));
ops1 = 1/ops2;
value2.setText(String.valueOf(ops1));
value1.setText("reciproc("+String.valueOf(ops2)+")");
}
});
//ALT+251
button_Sqr.setBackground(new Color(192, 192, 192));
button_Sqr.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
double ops = Double.parseDouble(String.valueOf(value2.getText()));
ops = Math.sqrt(ops);
value2.setText(String.valueOf(ops));
value1.setText("sqrt("+String.valueOf(ops*ops)+")");
}
});
button_Sqr.setFont(new Font("Cambria Math", Font.PLAIN, 13));
button_Sqr.setBounds(131, 138, 50, 31);
frmCalculator.getContentPane().add(button_Sqr);
button_rec.setFont(new Font("Cambria Math", Font.PLAIN, 11));
button_rec.setBounds(249, 222, 50, 31);
frmCalculator.getContentPane().add(button_rec);
//ALT+0177
button_neg.setBackground(new Color(192, 192, 192));
button_neg.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
double ops = Double.parseDouble(String.valueOf(value2.getText()));
ops = ops * (-1);
value2.setText(String.valueOf(ops));
value1.setText("negate("+String.valueOf(ops*-1)+")");
}
});
button_neg.setFont(new Font("Cambria Math", Font.PLAIN, 18));
button_neg.setBounds(191, 138, 50, 31);
frmCalculator.getContentPane().add(button_neg);
button_per.setBackground(new Color(192, 192, 192));
button_per.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
double ops = Double.parseDouble(String.valueOf(value2.getText()));
ops = ops * (100);
value2.setText(String.valueOf(ops));
value1.setText(String.valueOf(ops));
}
});
button_per.setBounds(249, 180, 50, 31);
frmCalculator.getContentPane().add(button_per);
button_equal.setBackground(new Color(60, 179, 113));
button_equal.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
fNumber = Double.parseDouble(value1.getText());
sNumber = Double.parseDouble(value2.getText());
if(operation.getText().equals("+"))
{
result = fNumber + sNumber ;
value1.setText(null);
value2.setText(String.valueOf(result));
}
else if(operation.getText().equals("-"))
{
result = fNumber - sNumber ;
value1.setText(null);
value2.setText(String.valueOf(result));
}
else if(operation.getText().equals("*"))
{
result = fNumber * sNumber ;
value1.setText(null);
value2.setText(String.valueOf(result));
}
else if(operation.getText().equals("/"))
{
result = fNumber / sNumber ;
value1.setText(null);
value2.setText(String.valueOf(result));
}
}
});
//ALT+8592
button_undo.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
String bkspace = null;
if(value2.getText().length() > 0)
{
StringBuilder strB = new StringBuilder(value2.getText());
strB.deleteCharAt(value2.getText().length() - 1);
bkspace = strB.toString();
value2.setText(bkspace);
}
}
});
button_undo.setFont(new Font("Cambria Math", Font.PLAIN, 19));
button_undo.setBounds(10, 138, 50, 31);
frmCalculator.getContentPane().add(button_undo);
button_equal.setFont(new Font("Cambria Math", Font.PLAIN, 18));
button_equal.setBounds(249, 264, 50, 73);
frmCalculator.getContentPane().add(button_equal);
btnExit.setBackground(new Color(255, 99, 71));
btnExit.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
System.exit(0);
}
});
btnExit.setFont(new Font("Cambria Math", Font.PLAIN, 12));
btnExit.setBounds(11, 348, 51, 23);
frmCalculator.getContentPane().add(btnExit);
}
/**
* @return the activate_and_Deactivate
*/
public Object getActivate_and_Deactivate() {
return Activate_and_Deactivate;
}
/**
* @param activate_and_Deactivate the activate_and_Deactivate to set
*/
public void setActivate_and_Deactivate(Object activate_and_Deactivate) {
Activate_and_Deactivate = activate_and_Deactivate;
}
}
package Calculators;
import javax.swing.JButton;
import javax.swing.JRadioButton;
public class Activate_and_Deactivate extends UIFrame
{
public void activate()
{
button0.setEnabled(true);
button1.setEnabled(true);
button2.setEnabled(true);
button3.setEnabled(true);
button4.setEnabled(true);
button5.setEnabled(true);
button6.setEnabled(true);
button7.setEnabled(true);
button8.setEnabled(true);
button9.setEnabled(true);
button_Div .setEnabled(true);
button_C .setEnabled(true);
button_Mul.setEnabled(true);
button_Add.setEnabled(true);
button_Sub.setEnabled(true);
button_Dot.setEnabled(true);
button_rec.setEnabled(true);
button_Sqr.setEnabled(true);
button_neg.setEnabled(true);
button_per .setEnabled(true);
button_equal.setEnabled(true);
button_undo .setEnabled(true);
btnExit .setEnabled(true);
rdbtnOff.setEnabled(true);
rdbtnOn.setEnabled(false);
}
public void deactivate()
{
button0.setEnabled(false);
button1.setEnabled(false);
button2.setEnabled(false);
button3.setEnabled(false);
button4.setEnabled(false);
button5.setEnabled(false);
button6.setEnabled(false);
button7.setEnabled(false);
button8.setEnabled(false);
button9.setEnabled(false);
button_Div .setEnabled(false);
button_C .setEnabled(false);
button_Mul.setEnabled(false);
button_Add.setEnabled(false);
button_Sub.setEnabled(false);
button_Dot.setEnabled(false);
button_rec.setEnabled(false);
button_Sqr.setEnabled(false);
button_neg.setEnabled(false);
button_per .setEnabled(false);
button_equal.setEnabled(false);
button_undo .setEnabled(false);
btnExit .setEnabled(false);
rdbtnOn.setEnabled(true);
rdbtnOff.setEnabled(false);
}
}
它不起作用。有人能帮我吗。 非常感谢。
答案 0 :(得分：0)
据我所知，您不能将基类用作派生类的实例。
但是，您可以将派生类的实例存储在基类中，然后在需要时将其强制转换回派生类。有关示例，请参见按钮上的ActionListener
基础
import java.awt.EventQueue;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
@SuppressWarnings("serial")
public class SimpleClass extends JFrame {
public SimpleClass(String title) {
super(title);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setLayout(new GridLayout());
setUp();
pack();
setLocationRelativeTo(null);
setVisible(true);
}
public SimpleClass() {
}
public void setUp() {
JPanel panel = new JPanel();
ExtendedClass e = new ExtendedClass();
SimpleClass s = new ExtendedClass();
SimpleClass thisInstance = this;
JButton button = new JButton("Press Me");
button.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent arg0) {
System.out.println(e instanceof ExtendedClass);
e.printLn();
System.out.println(s instanceof ExtendedClass);
((ExtendedClass)s).printLn();
System.out.println(thisInstance instanceof ExtendedClass);
//Returns an exception as it is not an instance of ExtendedClass
((ExtendedClass)thisInstance).printLn();
}
});
panel.add(button);
getContentPane().add(panel);
}
public static void main(String[] args) {
EventQueue.invokeLater(() -> new SimpleClass("Title"));
}
}
扩展
@SuppressWarnings("serial")
public class ExtendedClass extends SimpleClass {
public void printLn() {
System.out.println("Printed A Line To The Console :)");
}
}