我的JButton＆＃34; btnNew＆＃34;在Employee Constructor中的Employee类中没有禁用，我也不知道为什么。我是Java的新手，非常感谢任何帮助。我认为这是因为我将两个方法命名为actionPerformed，但是他们给了我一个没有相同名称的错误。
import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
import java.util.*;
abstract class Employee extends JFrame {
private Customers cust;
public Employee () {
setTitle("Employee");
SetLookandFeel();
setLayout(null);
setBounds(20,20,700,700);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JLabel lblID = new JLabel("Employee ID:");
JLabel lblFname = new JLabel("First Name:");
JLabel lblLname = new JLabel ("Last Name:");
JRadioButton rbMale = new JRadioButton("Male", false);
JRadioButton rbFemale = new JRadioButton("Female", false);
JLabel lblJob = new JLabel("Job Title:");
JLabel lblEmail = new JLabel("Email Address:");
JLabel lblLocation = new JLabel("Location:");
JLabel lblworkingdays = new JLabel("Working Days:");
JLabel lblDesc = new JLabel ("Job Description:");
JLabel lblGender = new JLabel("Gender");
final JTextArea txtDesc = new JTextArea(8,40);
JCheckBox chbxSun = new JCheckBox("Sunday");
JCheckBox chbxMon = new JCheckBox("Monday");
JCheckBox chbxTue = new JCheckBox("Tuesday");
JCheckBox chbxWed = new JCheckBox("Wednesday");
JCheckBox chbxThur = new JCheckBox("Thursday");
JCheckBox chbxFri = new JCheckBox("Friday");
JCheckBox chbxSat = new JCheckBox("Saturday");
final JTextField txtID = new JTextField();
final JTextField txtFname = new JTextField();
final JTextField txtLname = new JTextField();
final JTextField txtJob = new JTextField();
final JTextField txtEmail = new JTextField();
final JTextField txtLocate = new JTextField();
final JButton btnOpen = new JButton("Open");
final JButton btnNew = new JButton("Add Employee");
final JButton btnDelete = new JButton("Delete");
final JButton btnUpdate = new JButton("Update");
final JButton btnCancel = new JButton("Clear");
lblID.setBounds(20,20,100,20);
lblFname.setBounds(20,45,100,20);
lblLname.setBounds(20,70,100,20);
lblJob.setBounds(20,95,100,20);
lblEmail.setBounds(20,120,100,20);
lblLocation.setBounds(20,145,100,20);
lblworkingdays.setBounds(20,170,100,20);
lblDesc.setBounds(20,220,100,20);
lblGender.setBounds(20,320,100,20);
txtID.setBounds(150,20,230,25);
txtFname.setBounds(150,45,300,25);
txtLname.setBounds(150,70,300,25);
txtJob.setBounds(150,95,300,25);
txtEmail.setBounds(150,120,300,25);
txtLocate.setBounds(150,145,300,25);
rbMale.setBounds(150,320,100,20);
rbFemale.setBounds(250,320,100,20);
txtDesc.setBounds(150,220,300,100);
chbxMon.setBounds(150,170,100,20);
chbxTue.setBounds(250,170,100,20);
chbxWed.setBounds(350,170,100,20);
chbxThur.setBounds(450,170,100,20);
chbxFri.setBounds(550,170,100,20);
chbxSat.setBounds(150,195,100,20);
chbxSun.setBounds(250,195,100,20);
btnOpen.setBounds(400,20,80,20);
btnNew.setBounds(150,345,150,40);
btnDelete.setBounds(320,345,80,40);
btnUpdate.setBounds(420,345,80,40);
btnCancel.setBounds(150,600,80,40);
Container con = getContentPane();
con.add(lblID);
con.add(lblFname);
con.add(lblLname);
con.add(lblJob);
con.add(lblEmail);
con.add(lblLocation);
con.add(lblworkingdays);
con.add(lblDesc);
con.add(lblGender);
con.add(txtID);
con.add(txtFname);
con.add(txtLname);
con.add(txtJob);
con.add(txtEmail);
con.add(txtLocate);
con.add(rbMale);
con.add(rbFemale);
con.add(txtDesc);
con.add(chbxMon);
con.add(chbxTue);
con.add(chbxWed);
con.add(chbxThur);
con.add(chbxFri);
con.add(chbxSat);
con.add(chbxSun);
con.add(btnOpen);
con.add(btnNew);
con.add(btnDelete);
con.add(btnUpdate);
con.add(btnCancel);
setVisible(true);
btnCancel.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent ae) {
txtID.setText(null);
txtFname.setText(null);
txtLname.setText(null);
txtJob.setText(null);
txtEmail.setText(null);
txtLocate.setText(null);
txtDesc.setText(null);
}});
btnNew.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent ae) {
if (txtID.getText().length() > 0) {
btnNew.setEnabled(false);
}
else {
btnNew.setEnabled(true);
}
}});
}
private void SetLookandFeel() {
try {
UIManager.setLookAndFeel(
"com.sun.java.swing.plaf.nimbus.NimbusLookAndFeel");
} catch (Exception exc) {
}
}
public Customers getCustomers() {
return cust;
}
public void setCustomers (Customers cust) {
this.cust = cust;
}
}
class SalesPerson extends Employee {
public SalesPerson (Customers cust) {
setCustomers(cust);
}
}
class OtherStaff extends Employee {
}
class Customers extends Hashtable {
}
abstract class Customer extends JFrame {
JFrame frame = new JFrame();
public Customer(){
String[] days = {"01", "02", "03", "04", "05", "06", "07", "08", "09",
"10", "11", "12", "13", "14", "15", "16", "17", "18", "19", "20"
, "21", "22", "23", "24", "25", "26", "27", "28", "29", "30",
"31"};
String[] months = {"01", "02", "03", "04", "05", "06", "07", "08", "09"
,"10","11", "12"};
String[] years = {"40","41","42","43","44","45","46","47","48","49","50",
"51","52","53","54","55","56","57","58","59","60","61","62","63","64"
,"65","66","67","68","69","70","71","72","73","74","75","76","77"
,"78","79","80","81","82","83","84","85","86","87","88","89","90"
,"91","92","93","94","95","96","97","98","99"};
setTitle("Customer");
setLayout(null);
setBounds(20,20,700,700);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JLabel lblID = new JLabel("Customer ID:");
JLabel lblFname = new JLabel("First Name:");
JLabel lblLname = new JLabel("Last Name:");
JLabel lblStreet = new JLabel("Street:");
JLabel lblCity = new JLabel("City:");
JLabel lblZip = new JLabel("Zip Code:");
JLabel lblPhone = new JLabel("Phone:");
JLabel lblEmail = new JLabel("Email:");
JLabel lblDOB = new JLabel("DOB DD/MM/YY:");
JLabel lblPay = new JLabel("Cash or Credit?");
JRadioButton rbCash = new JRadioButton("Cash");
JRadioButton rbCredit = new JRadioButton("Credit");
final JTextField txtFname = new JTextField();
final JTextField txtLname = new JTextField();
final JTextField txtStreet = new JTextField();
final JTextField txtCity = new JTextField();
final JTextField txtZip = new JTextField();
final JTextField txtPhone = new JTextField();
final JTextField txtEmail = new JTextField();
JComboBox cbday = new JComboBox(days);
JComboBox cbmonth = new JComboBox(months);
JComboBox cbyear = new JComboBox(years);
final JTextField txtID = new JTextField();
JButton btnOpen = new JButton("Open");
JButton btnAdd = new JButton("Add Customer");
JButton btnDelete = new JButton("Delete");
JButton btnUpdate = new JButton("Update");
JButton btnCancel = new JButton("Clear");
lblID.setBounds(20,20,100,20);
lblFname.setBounds(20,45,100,20);
lblLname.setBounds(20,70,100,20);
lblStreet.setBounds(20,95,100,20);
lblCity.setBounds(20,120,100,20);
lblZip.setBounds(20,145,100,20);
lblPhone.setBounds(20,170,100,20);
lblEmail.setBounds(20,195,100,20);
lblDOB.setBounds(20,220,100,20);
lblPay.setBounds(20,245,100,20);
txtID.setBounds(150,20,230,25);
txtFname.setBounds(150,45,300,25);
txtLname.setBounds(150,70,300,25);
txtStreet.setBounds(150,95,300,25);
txtCity.setBounds(150,120,300,25);
txtZip.setBounds(150,145,300,25);
txtPhone.setBounds(150,170,300,25);
txtEmail.setBounds(150,195,300,25);
cbday.setBounds(150,220,50,20);
cbmonth.setBounds(200,220,50,20);
cbyear.setBounds(250,220,50,20);
rbCash.setBounds(150,245,100,20);
rbCredit.setBounds(250,245,100,20);
btnOpen.setBounds(400,20,80,20);
btnAdd.setBounds(150,270,150,40);
btnDelete.setBounds(320,270,80,40);
btnUpdate.setBounds(420,270,80,40);
btnCancel.setBounds(150,600,80,40);
Container con = getContentPane();
con.add(lblID);
con.add(lblFname);
con.add(lblLname);
con.add(lblStreet);
con.add(lblCity);
con.add(lblZip);
con.add(lblPhone);
con.add(lblEmail);
con.add(lblDOB);
con.add(lblPay);
con.add(txtID);
con.add(txtFname);
con.add(txtLname);
con.add(txtStreet);
con.add(txtCity);
con.add(txtZip);
con.add(txtPhone);
con.add(txtEmail);
con.add(cbday);
con.add(cbmonth);
con.add(cbyear);
con.add(rbCash);
con.add(rbCredit);
con.add(btnOpen);
con.add(btnAdd);
con.add(btnDelete);
con.add(btnUpdate);
con.add(btnCancel);
setVisible(true);
btnCancel.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent ae) {
txtID.setText(null);
txtFname.setText(null);
txtLname.setText(null);
txtCity.setText(null);
txtEmail.setText(null);
txtStreet.setText(null);
txtZip.setText(null);
txtPhone.setText(null);
}});
}
}
class CashCustomer extends Customer {
}
class CreditCustomer extends Customer {
}
class Tester {
public static void main(String[] args) {
new SalesPerson(new Customers());
new CashCustomer();
}
}
答案 0 :(得分：1)
除了关于使用布局管理器的注释之外，当动作发生在其对象上时，即当单击newBtn时，会发生actionPerformed。我认为你想要的是根据用户对txtID的操作实际启用和禁用此按钮。
要在JTextField上实现侦听器，请查看 Let ActionListener listen for change in JTextField instead of only enter?