我已编写此代码以从jTable获取数据并在控制台上显示它，但我遇到错误（线程中的异常＆＃34; AWT-EventQueue-0＆＃34; java.lang.NullPointerException）。请告诉我应该用什么条件来摆脱它。我想检查jTable的下一个条目是否为空，然后退出循环。 import java.io. ; import javax.swing。; import java.awt。*;
import javax.swing.JTable;
import javax.swing.table.AbstractTableModel;
import javax.swing.table.DefaultTableModel;
import javax.swing.table.TableModel;
import java.awt.event.ActionListener;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.StringTokenizer;
import javax.swing.JMenuItem;
import javax.swing.JPopupMenu;
import javax.swing.JSeparator;
public class SaleInvoice extends javax.swing.JFrame {
/**
* Creates new form SaleInvoice
*/
public SaleInvoice() {
setExtendedState(javax.swing.JFrame.MAXIMIZED_BOTH);
initComponents();
}
/**
* 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() {
jLabel1 = new javax.swing.JLabel();
jLabel2 = new javax.swing.JLabel();
jTextField1 = new javax.swing.JTextField();
jTextField2 = new javax.swing.JTextField();
jLabel3 = new javax.swing.JLabel();
jTextField3 = new javax.swing.JTextField();
jLabel4 = new javax.swing.JLabel();
jTextField4 = new javax.swing.JTextField();
label1 = new java.awt.Label();
label2 = new java.awt.Label();
label3 = new java.awt.Label();
label4 = new java.awt.Label();
jComboBox1 = new javax.swing.JComboBox();
jLabel5 = new javax.swing.JLabel();
jScrollPane1 = new javax.swing.JScrollPane();
jTable1 = new javax.swing.JTable();
jButton1 = new javax.swing.JButton();
jButton3 = new javax.swing.JButton();
jLabel6 = new javax.swing.JLabel();
jLabel7 = new javax.swing.JLabel();
jLabel8 = new javax.swing.JLabel();
jTextField5 = new javax.swing.JTextField();
jTextField6 = new javax.swing.JTextField();
jTextField7 = new javax.swing.JTextField();
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
setTitle("Sale Invoice");
setAlwaysOnTop(true);
setAutoRequestFocus(false);
setBackground(new java.awt.Color(255, 255, 255));
setCursor(new java.awt.Cursor(java.awt.Cursor.DEFAULT_CURSOR));
setResizable(false);
jLabel1.setText("Customer Name");
jLabel2.setText("Contact #");
jTextField2.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jTextField2ActionPerformed(evt);
}
});
jLabel3.setText("Bill No");
jLabel4.setText("Date");
jTextField4.setDisabledTextColor(new java.awt.Color(255, 255, 255));
jTextField4.setSelectionColor(new java.awt.Color(255, 255, 255));
label1.setFont(new java.awt.Font("Bodoni MT Black", 3, 48)); // NOI18N
label1.setText("Pak Madina Traders");
label2.setFont(new java.awt.Font("Dialog", 3, 18)); // NOI18N
label2.setText("Deals In All Kind Of New And Used Laptop ");
label3.setFont(new java.awt.Font("Dialog", 3, 16)); // NOI18N
label3.setText("59A 4th Floor Hafez Center Main Boulevard Gulberg III Lahore");
label4.setFont(new java.awt.Font("Dialog", 3, 16)); // NOI18N
label4.setText("Tel: 042 35717770 Email:pakmadinalaptop@hotmail.com");
jComboBox1.setModel(new javax.swing.DefaultComboBoxModel(new String[] { "Debit", "Credit" }));
jLabel5.setText("Bill Type");
jTable1.setBorder(javax.swing.BorderFactory.createLineBorder(new java.awt.Color(0, 0, 0)));
jTable1.setFont(new java.awt.Font("Verdana", 1, 14)); // NOI18N
jTable1.setModel(new javax.swing.table.DefaultTableModel(
new Object [][] {
{null, null, null, null, null, null},
{null, null, null, null, null, null},
{null, null, null, null, null, null},
{null, null, null, null, null, null},
{null, null, null, null, null, null},
{null, null, null, null, null, null},
{null, null, null, null, null, null},
{null, null, null, null, null, null},
{null, null, null, null, null, null},
{null, null, null, null, null, null},
{null, null, null, null, null, null},
{null, null, null, null, null, null},
{null, null, null, null, null, null},
{null, null, null, null, null, null},
{null, null, null, null, null, null},
{null, null, null, null, null, null},
{null, null, null, null, null, null},
{null, null, null, null, null, null},
{null, null, null, null, null, null},
{null, null, null, null, null, null}
},
new String [] {
"Sr #", "Product Description", "Lot #", "Qty", "Rate", "Amount"
}
) {
Class[] types = new Class [] {
java.lang.Integer.class, java.lang.String.class, java.lang.String.class, java.lang.Integer.class, java.lang.Integer.class, java.lang.Integer.class
};
public Class getColumnClass(int columnIndex) {
return types [columnIndex];
}
});
jTable1.setAutoResizeMode(javax.swing.JTable.AUTO_RESIZE_OFF);
jTable1.setColumnSelectionAllowed(true);
jTable1.setCursor(new java.awt.Cursor(java.awt.Cursor.TEXT_CURSOR));
jTable1.setGridColor(new java.awt.Color(0, 0, 0));
jTable1.setName(""); // NOI18N
jTable1.setRowHeight(30);
jTable1.setSelectionBackground(new java.awt.Color(255, 255, 255));
jTable1.setSelectionMode(javax.swing.ListSelectionModel.SINGLE_SELECTION);
jTable1.setSurrendersFocusOnKeystroke(true);
jScrollPane1.setViewportView(jTable1);
jTable1.getColumnModel().getSelectionModel().setSelectionMode(javax.swing.ListSelectionModel.SINGLE_SELECTION);
if (jTable1.getColumnModel().getColumnCount() > 0) {
jTable1.getColumnModel().getColumn(0).setResizable(false);
jTable1.getColumnModel().getColumn(0).setPreferredWidth(60);
jTable1.getColumnModel().getColumn(1).setPreferredWidth(400);
jTable1.getColumnModel().getColumn(2).setResizable(false);
jTable1.getColumnModel().getColumn(3).setResizable(false);
jTable1.getColumnModel().getColumn(3).setPreferredWidth(80);
jTable1.getColumnModel().getColumn(4).setResizable(false);
jTable1.getColumnModel().getColumn(4).setPreferredWidth(150);
jTable1.getColumnModel().getColumn(5).setPreferredWidth(170);
}
jButton1.setText("Submit");
jButton1.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
// jButton1ActionPerformed(evt);
if(evt.getSource()==jButton1)
{
int col=0,row=0;
String SR,PD,LOT,QTY,RATE,AMT;//check=jTable1.getValueAt(row, col).toString();
int count=jTable1.getRowCount();
for(row = 0 ;(!(jTable1.getValueAt(row, col).toString()).equals(null)); row++)
{
SR=new String(jTable1.getValueAt(row, col).toString());
col++;
PD=new String(jTable1.getValueAt(row, col).toString());
col++;
LOT=new String(jTable1.getValueAt(row, col).toString());
col++;
QTY=new String(jTable1.getValueAt(row, col).toString());
col++;
RATE=new String(jTable1.getValueAt(row, col).toString());
col++;
AMT=new String(jTable1.getValueAt(row, col).toString());
System.out.println("Sr# : " + SR);
System.out.println("Product Discription : " + PD);
System.out.println("Lot# : " + LOT);
System.out.println("Quantity : " + QTY);
System.out.println("Rate : " + RATE);
System.out.println("Amount : " + AMT);
col=0;
//check=jTable1.getValueAt(row, col).toString();
}
}
}
});
jButton3.setText("Back ");
jButton3.setCursor(new java.awt.Cursor(java.awt.Cursor.DEFAULT_CURSOR));
jLabel6.setFont(new java.awt.Font("Dialog", 3, 14)); // NOI18N
jLabel6.setText("Total");
jLabel7.setFont(new java.awt.Font("Dialog", 3, 14)); // NOI18N
jLabel7.setText("ADVANCE");
jLabel8.setFont(new java.awt.Font("Dialog", 3, 14)); // NOI18N
jLabel8.setText("BALANCE");
jTextField5.setFont(new java.awt.Font("Dialog", 3, 14)); // NOI18N
jTextField6.setFont(new java.awt.Font("Dialog", 1, 14)); // NOI18N
jTextField6.setCursor(new java.awt.Cursor(java.awt.Cursor.TEXT_CURSOR));
jTextField7.setFont(new java.awt.Font("Dialog", 1, 14)); // NOI18N
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addGap(54, 54, 54)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
.addComponent(jLabel2, javax.swing.GroupLayout.PREFERRED_SIZE, 92, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(jLabel1))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
.addComponent(jTextField2, javax.swing.GroupLayout.PREFERRED_SIZE, 292, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
.addComponent(jLabel4, javax.swing.GroupLayout.PREFERRED_SIZE, 75, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGap(13, 13, 13)
.addComponent(jTextField4, javax.swing.GroupLayout.PREFERRED_SIZE, 292, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGroup(layout.createSequentialGroup()
.addComponent(jScrollPane1, javax.swing.GroupLayout.PREFERRED_SIZE, 953, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
.addComponent(jButton1, javax.swing.GroupLayout.PREFERRED_SIZE, 152, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGroup(layout.createSequentialGroup()
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(jLabel7, javax.swing.GroupLayout.PREFERRED_SIZE, 79, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(jLabel8, javax.swing.GroupLayout.PREFERRED_SIZE, 79, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(jLabel6, javax.swing.GroupLayout.PREFERRED_SIZE, 79, javax.swing.GroupLayout.PREFERRED_SIZE))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
.addComponent(jTextField7)
.addComponent(jTextField6)
.addComponent(jTextField5, javax.swing.GroupLayout.PREFERRED_SIZE, 155, javax.swing.GroupLayout.PREFERRED_SIZE)))
.addComponent(jButton3, javax.swing.GroupLayout.PREFERRED_SIZE, 152, javax.swing.GroupLayout.PREFERRED_SIZE)))
.addGroup(layout.createSequentialGroup()
.addGap(110, 110, 110)
.addComponent(jTextField1, javax.swing.GroupLayout.PREFERRED_SIZE, 292, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(label1, javax.swing.GroupLayout.PREFERRED_SIZE, 643, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGroup(layout.createSequentialGroup()
.addGap(56, 56, 56)
.addComponent(label2, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
.addComponent(label3, javax.swing.GroupLayout.PREFERRED_SIZE, 605, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGroup(layout.createSequentialGroup()
.addGap(21, 21, 21)
.addComponent(label4, javax.swing.GroupLayout.PREFERRED_SIZE, 479, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGroup(layout.createSequentialGroup()
.addComponent(jLabel3, javax.swing.GroupLayout.PREFERRED_SIZE, 75, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(jTextField3, javax.swing.GroupLayout.PREFERRED_SIZE, 292, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGap(55, 55, 55)
.addComponent(jLabel5, javax.swing.GroupLayout.PREFERRED_SIZE, 57, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGap(81, 81, 81)
.addComponent(jComboBox1, javax.swing.GroupLayout.PREFERRED_SIZE, 214, javax.swing.GroupLayout.PREFERRED_SIZE)))))
.addContainerGap(80, Short.MAX_VALUE))
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addGap(18, 18, 18)
.addComponent(label1, javax.swing.GroupLayout.PREFERRED_SIZE, 59, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGap(19, 19, 19)
.addComponent(label2, javax.swing.GroupLayout.PREFERRED_SIZE, 36, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGap(10, 10, 10)
.addComponent(label3, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGap(19, 19, 19)
.addComponent(label4, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(jLabel1, javax.swing.GroupLayout.PREFERRED_SIZE, 29, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(jTextField1, javax.swing.GroupLayout.PREFERRED_SIZE, 29, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(jLabel3, javax.swing.GroupLayout.PREFERRED_SIZE, 29, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(jTextField3, javax.swing.GroupLayout.PREFERRED_SIZE, 29, javax.swing.GroupLayout.PREFERRED_SIZE))
.addComponent(jLabel5, javax.swing.GroupLayout.PREFERRED_SIZE, 29, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(jComboBox1, javax.swing.GroupLayout.PREFERRED_SIZE, 29, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(18, 18, 18)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(jLabel2, javax.swing.GroupLayout.PREFERRED_SIZE, 29, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(jTextField2, javax.swing.GroupLayout.PREFERRED_SIZE, 29, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(jTextField4, javax.swing.GroupLayout.PREFERRED_SIZE, 29, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(jLabel4, javax.swing.GroupLayout.PREFERRED_SIZE, 29, javax.swing.GroupLayout.PREFERRED_SIZE)))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
.addGroup(layout.createSequentialGroup()
.addGap(1, 1, 1)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(jLabel6, javax.swing.GroupLayout.PREFERRED_SIZE, 29, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(jTextField5, javax.swing.GroupLayout.PREFERRED_SIZE, 29, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(28, 28, 28)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
.addComponent(jLabel7, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addComponent(jTextField7, javax.swing.GroupLayout.PREFERRED_SIZE, 29, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(27, 27, 27)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
.addComponent(jLabel8, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addComponent(jTextField6, javax.swing.GroupLayout.PREFERRED_SIZE, 29, javax.swing.GroupLayout.PREFERRED_SIZE))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addComponent(jButton1, javax.swing.GroupLayout.PREFERRED_SIZE, 38, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGap(60, 60, 60)
.addComponent(jButton3, javax.swing.GroupLayout.PREFERRED_SIZE, 38, javax.swing.GroupLayout.PREFERRED_SIZE))
.addComponent(jScrollPane1, javax.swing.GroupLayout.PREFERRED_SIZE, 347, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(90, 90, 90))
);
setBounds(0, 0, 1373, 773);
}// </editor-fold>
private void jTextField2ActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
}
private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
}
/**
* @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 ("Metal".equals(info.getName())) {
javax.swing.UIManager.setLookAndFeel(info.getClassName());
break;
}
}
} catch (ClassNotFoundException ex) {
java.util.logging.Logger.getLogger(SaleInvoice.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (InstantiationException ex) {
java.util.logging.Logger.getLogger(SaleInvoice.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (IllegalAccessException ex) {
java.util.logging.Logger.getLogger(SaleInvoice.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (javax.swing.UnsupportedLookAndFeelException ex) {
java.util.logging.Logger.getLogger(SaleInvoice.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 SaleInvoice().setVisible(true);
}
});
}
// Variables declaration - do not modify
private javax.swing.JButton jButton1;
private javax.swing.JButton jButton3;
private javax.swing.JComboBox jComboBox1;
private javax.swing.JLabel jLabel1;
private javax.swing.JLabel jLabel2;
private javax.swing.JLabel jLabel3;
private javax.swing.JLabel jLabel4;
private javax.swing.JLabel jLabel5;
private javax.swing.JLabel jLabel6;
private javax.swing.JLabel jLabel7;
private javax.swing.JLabel jLabel8;
private javax.swing.JScrollPane jScrollPane1;
private javax.swing.JTable jTable1;
private javax.swing.JTextField jTextField1;
private javax.swing.JTextField jTextField2;
private javax.swing.JTextField jTextField3;
private javax.swing.JTextField jTextField4;
private javax.swing.JTextField jTextField5;
private javax.swing.JTextField jTextField6;
private javax.swing.JTextField jTextField7;
private java.awt.Label label1;
private java.awt.Label label2;
private java.awt.Label label3;
private java.awt.Label label4;
// End of variables declaration
}
请给我一些解决方案，我将非常感谢你。
答案 0 :(得分：1)
在条件
之前进行空检查if (jTable1.getValueAt(row, col) != null) {
final String string = jTable1.getValueAt(row, col).toString();
for(row = 0; row != null; row++) {
//your code
}
}