我目前正在创建一个工资单软件，RemoveEmployee类由于错误而无法运行。我试着逆向工作来解决这个问题，但由于缺乏java经验，我无法解决。
package Assigment;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Vector;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.swing.JOptionPane;
import javax.swing.table.DefaultTableModel;
/**
*
* @author dj_sp
*/
public class RemoveEmployee extends javax.swing.JFrame {
File sallaried=new File("Salaried Employee Registration.txt");
File hourly=new File("Hourly Employee Registration.txt");
File commission=new File("Commission Employee Registration.txt");
//creating a text files
/**
* Creates new form RemoveEmployee
*/
public RemoveEmployee() {
initComponents();
removeSalEmp();
removeHourlyEmp();
removeCommissionEmp();
//calling methods
}
public void removeSemp(){
}
public void removeSalEmp(){
DefaultTableModel model=(DefaultTableModel)tblSalaried.getModel();
FileReader fr;
try {
fr = new FileReader(sallaried);
BufferedReader br=new BufferedReader(fr);
//reading from text file
String line;
int column;
int row=0;
while(( line=br.readLine())!=null){
tblSalaried.setValueAt(line,row,0);
tblSalaried.setValueAt(br.readLine(),row,1);
tblSalaried.setValueAt(br.readLine(),row,2);
tblSalaried.setValueAt(br.readLine(),row,3);
tblSalaried.setValueAt(br.readLine(),row,4);
tblSalaried.setValueAt(br.readLine(),row,5);
tblSalaried.setValueAt(br.readLine(),row,6);
tblSalaried.setValueAt(br.readLine(),row,7);
tblSalaried.setValueAt(br.readLine(),row,8);
tblSalaried.setValueAt(br.readLine(),row,9);
row++;
//sets to a jtable
}
br.close();
fr.close();
} catch (FileNotFoundException ex) {
Logger.getLogger(RemoveEmployee.class.getName()).log(Level.SEVERE, null, ex);
} catch (IOException ex) {
Logger.getLogger(RemoveEmployee.class.getName()).log(Level.SEVERE, null, ex);
}
}
public void removeHourlyEmp(){
DefaultTableModel table =(DefaultTableModel)tblSalaried.getModel();
FileReader fr;
try {
fr = new FileReader(hourly);
BufferedReader br=new BufferedReader(fr);
String line;
int column;
int row=0;
while(( line=br.readLine())!=null){
tblHourly.setValueAt(line,row,0);
tblHourly.setValueAt(br.readLine(),row,1);
tblHourly.setValueAt(br.readLine(),row,2);
tblHourly.setValueAt(br.readLine(),row,3);
tblHourly.setValueAt(br.readLine(),row,4);
tblHourly.setValueAt(br.readLine(),row,5);
tblHourly.setValueAt(br.readLine(),row,6);
tblHourly.setValueAt(br.readLine(),row,7);
tblHourly.setValueAt(br.readLine(),row,8);
row++;
}
br.close();
fr.close();
} catch (FileNotFoundException ex) {
Logger.getLogger(RemoveEmployee.class.getName()).log(Level.SEVERE, null, ex);
} catch (IOException ex) {
Logger.getLogger(RemoveEmployee.class.getName()).log(Level.SEVERE, null, ex);
}
}
public void removeCommissionEmp(){
DefaultTableModel model=(DefaultTableModel)tblCommission.getModel();
FileReader fr;
try {
fr = new FileReader(commission);
BufferedReader br=new BufferedReader(fr);
String line;
int column;
int row=0;
while(( line=br.readLine())!=null){
tblCommission.setValueAt(line,row,0);
tblCommission.setValueAt(br.readLine(),row,1);
tblCommission.setValueAt(br.readLine(),row,2);
tblCommission.setValueAt(br.readLine(),row,3);
tblCommission.setValueAt(br.readLine(),row,4);
tblCommission.setValueAt(br.readLine(),row,5);
tblCommission.setValueAt(br.readLine(),row,6);
tblCommission.setValueAt(br.readLine(),row,7);
tblCommission.setValueAt(br.readLine(),row,8);
tblCommission.setValueAt(br.readLine(),row,9);
row++;
}
br.close();
fr.close();
} catch (FileNotFoundException ex) {
Logger.getLogger(RemoveEmployee.class.getName()).log(Level.SEVERE, null, ex);
} catch (IOException ex) {
Logger.getLogger(RemoveEmployee.class.getName()).log(Level.SEVERE, null, ex);
}
}
/**
* This method is called from within the constructor to initialize the form.
* WARNING: Do NOT modify this code. The content ofs("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>
// Variables declaration - do not modify
// End of variables declaration
private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {
DefaultTableModel model=(DefaultTableModel)tblSalaried.getModel();
int selectedRow=tblSalaried.getSelectedRow();
int dialogResult = JOptionPane.showConfirmDialog(null,"Would you like to remove selected employee");
//displays confirmation dialog to user
if(dialogResult == JOptionPane.YES_OPTION){
model.removeRow(selectedRow);
//gets the user answer and if true removes employee from table
String newwFile = "Salaried Employee Registration2.txt";
//creating new text file
File newFile = new File(newwFile);
try {
FileWriter fw = new FileWriter(newFile);
BufferedWriter bw = new BufferedWriter(fw);
int rowCount=tblSalaried.getRowCount();
for(int i = 0; i < tblSalaried.getRowCount(); i++){//rows
for(int j = 0; j < tblSalaried.getColumnCount(); j++){//columns
//
if(tblSalaried.getValueAt(i,j)!=null){
bw.write((String) tblSalaried.getValueAt(i,j));
bw.newLine();
}
//writing to a file while jtable is nt equal to nothing
}
}
JOptionPane.showMessageDialog(null, "Employee has been removed from the system");
//display a message to user
bw.close();
fw.close();
sallaried.delete();
newFile.renameTo(sallaried);
//deletes old file,
// renames new file to the old file
} catch (IOException ex) {
Logger.getLogger(RemoveEmployee.class.getName()).log(Level.SEVERE, null, ex);
}
}else
{
}
}
private void jButton2ActionPerformed(java.awt.event.ActionEvent evt) {
MainMenu FirstMenu=new MainMenu();
MainMenu.setVisible(true);
this.setVisible(false);
}
private void jButton3ActionPerformed(java.awt.event.ActionEvent evt) {
DefaultTableModel model=(DefaultTableModel)tblHourly.getModel();
int selectedRow=tblHourly.getSelectedRow();
int dialogResult = JOptionPane.showConfirmDialog(null,"Would you like to remove selected employee");
if(dialogResult == JOptionPane.YES_OPTION){
model.removeRow(selectedRow);
String newwFile = "Hourly Employee Registration2.txt";
File newFile = new File(newwFile);
try {
FileWriter fw = new FileWriter(newFile);
BufferedWriter bw = new BufferedWriter(fw);
int rowCount=tblHourly.getRowCount();
for(int i = 0; i < tblHourly.getRowCount(); i++){//rows
for(int j = 0; j < tblHourly.getColumnCount(); j++){//columns
if(tblHourly.getValueAt(i,j)!=null){
bw.write((String) tblHourly.getValueAt(i,j));
bw.newLine();
}
}
}
JOptionPane.showMessageDialog(null, "Employee has been removed from the system");
bw.close();
fw.close();
hourly.delete();
newFile.renameTo(hourly);
} catch (IOException ex) {
Logger.getLogger(RemoveEmployee.class.getName()).log(Level.SEVERE, null, ex);
}
}
}
private void jButton4ActionPerformed(java.awt.event.ActionEvent evt) {
DefaultTableModel model=(DefaultTableModel)tblCommission.getModel();
int selectedRow=tblCommission.getSelectedRow();
int dialogResult = JOptionPane.showConfirmDialog(null,"Would you like to remove selected employee");
if(dialogResult == JOptionPane.YES_OPTION){
model.removeRow(selectedRow);
String newwFile = "Commission Employee Registration2.txt";
File newFile = new File(newwFile);
try {
FileWriter fw = new FileWriter(newFile);
BufferedWriter bw = new BufferedWriter(fw);
int rowCount=tblCommission.getRowCount();
for(int i = 0; i < tblCommission.getRowCount(); i++){//rows
for(int j = 0; j < tblCommission.getColumnCount(); j++){//columns
if(tblCommission.getValueAt(i,j)!=null){
bw.write((String) tblCommission.getValueAt(i,j));
bw.newLine();
}
}
}
JOptionPane.showMessageDialog(null, "Employee has been removed from the system");
bw.close();
fw.close();
commission.delete();
newFile.renameTo(commission);
} catch (IOException ex) {
Logger.getLogger(RemoveEmployee.class.getName()).log(Level.SEVERE, null, ex);
}
}
}
/**
* @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(RemoveEmployee.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (InstantiationException ex) {
java.util.logging.Logger.getLogger(RemoveEmployee.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (IllegalAccessException ex) {
java.util.logging.Logger.getLogger(RemoveEmployee.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (javax.swing.UnsupportedLookAndFeelException ex) {
java.util.logging.Logger.getLogger(RemoveEmployee.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 RemoveEmployee().setVisible(true);
}
});
}
// Variables declaration - do not modify
private javax.swing.JButton jButton1;
private javax.swing.JButton jButton2;
private javax.swing.JButton jButton3;
private javax.swing.JButton jButton4;
private javax.swing.JLabel jLabel1;
private javax.swing.JLabel jLabel2;
private javax.swing.JLabel jLabel3;
private javax.swing.JLabel jLabel4;
private javax.swing.JPanel jPanel2;
private javax.swing.JScrollPane jScrollPane1;
private javax.swing.JScrollPane jScrollPane2;
private javax.swing.JScrollPane jScrollPane3;
private javax.swing.JSeparator jSeparator1;
private javax.swing.JSeparator jSeparator2;
private javax.swing.JSeparator jSeparator3;
private javax.swing.JTable tblCommission;
private javax.swing.JTable tblHourly;
private javax.swing.JTable tblSalaried;
// End of variables declaration
}
我收到的错误消息。除此之外，我的所有其他类都在运行。我尝试重新初始化构造函数，但没有任何帮助。
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at Assigment.RemoveEmployee.removeSalEmp(RemoveEmployee.java:47)
at Assigment.RemoveEmployee.<init>(RemoveEmployee.java:37)
at Assigment.RemoveEmployee$1.run(RemoveEmployee.java:376)
at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:311)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:756)
at java.awt.EventQueue.access$500(EventQueue.java:97)
at java.awt.EventQueue$3.run(EventQueue.java:709)
at java.awt.EventQueue$3.run(EventQueue.java:703)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:76)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:726)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)
在您发布的代码中，我看不出您在哪里为tblSalaried赋值。它是RemoveEmployee类的成员。除非你给它赋值，否则它是空的。因此，当您尝试访问它时，您会得到NullPointerException。根据您发布的代码以及您发布的堆栈跟踪，NullPointerException是从这一行抛出的(在方法removeSalEmp()中(：
DefaultTableModel model=(DefaultTableModel)tblSalaried.getModel();
这将是文件RemoveEmployee.java中的第47行，正如您发布的堆栈跟踪中所述。
我建议在initComponents()方法中初始化类成员，如tblSalaried。您需要添加以下内容：
tblSalaried = new JTable();
就您的信息而言，我看到您的代码还有一些其他问题，但我认为您最好先自己发现它们。你可以随时发布另一个问题：-(