你好，我是一个新的程序员，因此我对编程了解不多，我遇到了不少错误，有些错误已经解决了，而有些错误我完全不明白。程序本身编译得很完美，但是当我运行它时，它却给我带来了一些复杂的问题。这是我的程序。
import java.awt.EventQueue;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import java.awt.Font;
import java.awt.SystemColor;
import java.util.ArrayList;
import java.util.LinkedList;
import java.util.List;
import java.util.Vector;
import javax.swing.SwingConstants;
import javax.swing.JTable;
import javax.swing.JScrollPane;
import javax.swing.table.DefaultTableModel;
import javax.swing.table.TableModel;
import javax.swing.JTextField;
import javax.swing.JButton;
import javax.swing.ImageIcon;
import java.awt.Color;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import java.awt.Toolkit;
import javax.swing.JComboBox;
import javax.swing.JTextPane;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import javax.swing.table.DefaultTableModel;
import javax.swing.table.TableModel;
import javax.swing.GroupLayout.Alignment;
import javax.swing.GroupLayout;
import javax.swing.LayoutStyle.ComponentPlacement;
public class BismillahKasir2 extends javax.swing.JFrame {
private static final Object Datang = null;
private JFrame frame;
private JTable table;
private JTextField tfKODE;
private JTextField tfNAMA;
private JTextField tfSATUAN;
private JTextField tfBANYAK;
private JTextField tfTOTAL;
private JTable tblKERANJANG;
private JTextField TFBAYAR;
private JTextField tfKEMBALI;
private JTextField tfSUM;
/**
* Launch the application.
*/
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
BismillahKasir2 window = new BismillahKasir2();
window.frame.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
/**
* Create the application.
*/
public BismillahKasir2() {
initComponents();
JOptionPane.showMessageDialog(null, "Selamat Datang di Stationaries CORNER!");
}
/**
* Initialize the contents of the frame.
*/
private void initComponents() {
frame = new JFrame();
frame.setUndecorated(true);
frame.setIconImage(Toolkit.getDefaultToolkit().getImage("C:\\Users\\LENOVO\\eclipse-workspace\\2018Etugasakhir\\STATIONARY4.png"));
frame.setTitle("Stationaries CORNER");
frame.setBackground(SystemColor.activeCaption);
frame.getContentPane().setBackground(Color.BLUE);
frame.getContentPane().setFont(new Font("Berlin Sans FB", Font.BOLD, 25));
frame.setBounds(100, 100, 800, 562);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().setLayout(null);
JButton btnHitung = new JButton("Hitung");
JButton btnTotal = new JButton("Total");
btnTotal.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
btnHitungActionPerformed(evt);
}
});
btnTotal.setFont(new Font("Tahoma", Font.PLAIN, 14));
btnTotal.setBounds(213, 527, 89, 23);
frame.getContentPane().add(btnTotal);
JButton btnCetakNota = new JButton("Cetak Nota");
btnCetakNota.setFont(new Font("Tahoma", Font.PLAIN, 14));
btnCetakNota.setBounds(438, 520, 104, 29);
frame.getContentPane().add(btnCetakNota);
tfKEMBALI = new JTextField();
tfKEMBALI.setEditable(false);
tfKEMBALI.setBounds(400, 480, 185, 29);
frame.getContentPane().add(tfKEMBALI);
tfKEMBALI.setColumns(10);
JLabel lblKembalian = new JLabel("Kembalian:");
lblKembalian.setFont(new Font("Tahoma", Font.PLAIN, 14));
lblKembalian.setForeground(Color.WHITE);
lblKembalian.setBounds(330, 487, 72, 14);
frame.getContentPane().add(lblKembalian);
JButton btnBayar = new JButton("Bayar");
btnBayar.setFont(new Font("Tahoma", Font.PLAIN, 14));
btnBayar.setBounds(445, 447, 89, 23);
frame.getContentPane().add(btnBayar);
TFBAYAR = new JTextField();
TFBAYAR.setFont(new Font("Tahoma", Font.PLAIN, 14));
TFBAYAR.setBounds(400, 411, 185, 29);
frame.getContentPane().add(TFBAYAR);
TFBAYAR.setColumns(10);
JLabel lblJumlahBayar = new JLabel("Bayar:");
lblJumlahBayar.setForeground(Color.WHITE);
lblJumlahBayar.setFont(new Font("Tahoma", Font.PLAIN, 14));
lblJumlahBayar.setBounds(330, 418, 57, 16);
frame.getContentPane().add(lblJumlahBayar);
JLabel lblJumlah = new JLabel("Jumlah:");
lblJumlah.setFont(new Font("Tahoma", Font.PLAIN, 14));
lblJumlah.setForeground(Color.WHITE);
lblJumlah.setBounds(330, 376, 57, 14);
frame.getContentPane().add(lblJumlah);
tblKERANJANG = new JTable();
tblKERANJANG.setFont(new Font("Tahoma", Font.PLAIN, 10));
tblKERANJANG.setModel(new DefaultTableModel(
new Object[][] {
{null, null},
},
new String[] {
"Barang", "Total"
}
));
tblKERANJANG.getColumnModel().getColumn(0).setPreferredWidth(100);
tblKERANJANG.setShowVerticalLines(false);
tblKERANJANG.setShowHorizontalLines(false);
tblKERANJANG.setShowGrid(false);
tblKERANJANG.setBorder(null);
tblKERANJANG.setBounds(99, 365, 221, 151);
frame.getContentPane().add(tblKERANJANG);
JLabel lblKeranjangBelanja = new JLabel("Keranjang:");
lblKeranjangBelanja.setForeground(Color.WHITE);
lblKeranjangBelanja.setFont(new Font("Tahoma", Font.PLAIN, 14));
lblKeranjangBelanja.setBounds(10, 429, 89, 22);
frame.getContentPane().add(lblKeranjangBelanja);
JScrollPane scrollPane = new JScrollPane();
scrollPane.setBounds(309, 62, 465, 292);
frame.getContentPane().add(scrollPane);
Object [] Kolom = {"Kode Barang", "Nama Barang", "Harga"};
DefaultTableModel tabel = new DefaultTableModel();
tabel.setColumnIdentifiers(Kolom);
LinkedList<String> kode = new LinkedList<String>();
kode.add("1901001");
kode.add("1901002");
kode.add("1901003");
kode.add("1901004");
kode.add("1901005");
kode.add("1901006");
kode.add("1901007");
kode.add("1901008");
kode.add("1901009");
kode.add("1901010");
kode.add("1902001");
kode.add("1902002");
kode.add("1902003");
kode.add("1902004");
kode.add("1902005");
kode.add("1902006");
kode.add("1902007");
kode.add("1902008");
kode.add("1903001");
kode.add("1903002");
kode.add("1903003");
kode.add("1903004");
kode.add("1904001");
kode.add("1904002");
kode.add("1904003");
kode.add("1905001");
kode.add("1905002");
kode.add("1905003");
kode.add("1905004");
kode.add("1905005");
kode.add("1905006");
kode.add("1905007");
kode.add("1905008");
kode.add("1905009");
kode.add("1905010");
kode.add("1906001");
kode.add("1906002");
kode.add("1906003");
kode.add("1906004");
kode.add("1906005");
kode.add("1906006");
kode.add("1906007");
kode.add("1906008");
kode.add("1906009");
kode.add("1906010");
kode.add("1907001");
kode.add("1907002");
kode.add("1907003");
kode.add("1907004");
kode.add("1907005");
kode.add("1907006");
kode.add("1907007");
kode.add("1907008");
kode.add("1907009");
kode.add("1907010");
LinkedList<String> namabarang = new LinkedList<String>();
namabarang.add("Estude Drawing Book A3");
namabarang.add("VOS E Buku Tulis 58");
namabarang.add("VOS E Buku Tulis 38");
namabarang.add("Estudee E Buku Tulis 58 isi 10");
namabarang.add("Estudee B Buku Tulis Tribal isi 5");
namabarang.add("Vos Buku Tulis Tartan isi 5");
namabarang.add("Vos E Buku Tulis 38 Isi 5");
namabarang.add("Buku Kuitansi Besar");
namabarang.add("Buku Kuitansi Kecil");
namabarang.add("Buku Kuitansi Sedang");
namabarang.add("Paper Art");
namabarang.add("HVS A4 70 gr SIDU 1 box");
namabarang.add("HVS A4 70 gr SIDU 1 rim");
namabarang.add("HVS F4 70 gr SIDU 1 box");
namabarang.add("HVS F4 70 gr SIDU 1 rim");
namabarang.add("Kertas Sertifikat A4 1 pak");
namabarang.add("Kertas Sertifikat A4 per lembar");
namabarang.add("Folio Bergaris F4");
namabarang.add("Cat Air Titi 12 warna");
namabarang.add("Pensil Warna Fabercastell 48");
namabarang.add("Krayon Fabercastell");
namabarang.add("Stabilo JOYKO");
namabarang.add("Tinta Printer Warna Epson 664 per pcs");
namabarang.add("Tinta Printer Warna Epson 664 1 pak");
namabarang.add("Tinta Stempel ARTLINE Biru");
namabarang.add("Deli White Glue 9070");
namabarang.add("3M Double Side Tape 18mm");
namabarang.add("3M Brown Packaging Tape 48x50");
namabarang.add("3M Scotch Multipurpose Scissors");
namabarang.add("Kid Blunt Scissor");
namabarang.add("3M Clear Packaging Tape 48x50");
namabarang.add("Isolasi Bening Nachi 2");
namabarang.add("Isolasi Bening Nachi 1/2");
namabarang.add("Lem Cair Povinal 75 ml");
namabarang.add("Gunting Kenko Scissors");
namabarang.add("Faber Pena Tripen Set 4");
namabarang.add("Standard R8 Blue");
namabarang.add("Snowman B. Marker Abg-12");
namabarang.add("Deli Student Ruler Flexible");
namabarang.add("Deli White Board Marker (Black)");
namabarang.add("Standard BCOOL Black Set 12");
namabarang.add("Standard Permanent Marker Black");
namabarang.add("Standard Blive Nox Black Set 12");
namabarang.add("TIP EX JOYKO Cair");
namabarang.add("TIP EX Kertas Kenko");
namabarang.add("3M Post It Note Page Marker 670");
namabarang.add("Deli Thumb Tack E0020");
namabarang.add("Deli Transparent Push Pin E0030");
namabarang.add("3M Tape Dispenser Black C60");
namabarang.add("Stapler HD - 12N13 BESAR");
namabarang.add("Stapler MAX HD-10");
namabarang.add("Plastik Mika F4 (isi 100)");
namabarang.add("Amplop Paperline Polos 90");
namabarang.add("Amplop Coklat uk.folio");
namabarang.add("Penghapus Papan Tulis");
LinkedList<String> harga = new LinkedList<String>();
harga.add("13000");
harga.add("59000");
harga.add("45000");
harga.add("59000");
harga.add("34500");
harga.add("34500");
harga.add("45000");
harga.add("6000");
harga.add("2500");
harga.add("4500");
harga.add("98000");
harga.add("170000");
harga.add("45000");
harga.add("200000");
harga.add("60000");
harga.add("90000");
harga.add("1000");
harga.add("20000");
harga.add("84000");
harga.add("94000");
harga.add("125000");
harga.add("8000");
harga.add("85000");
harga.add("320000");
harga.add("21000");
harga.add("8000");
harga.add("21000");
harga.add("38500");
harga.add("59500");
harga.add("34000");
harga.add("37500");
harga.add("5000");
harga.add("2000");
harga.add("4000");
harga.add("9000");
harga.add("13000");
harga.add("6000");
harga.add("9500");
harga.add("13000");
harga.add("7500");
harga.add("57500");
harga.add("10500");
harga.add("57500");
harga.add("6000");
harga.add("12000");
harga.add("23500");
harga.add("9000");
harga.add("28500");
harga.add("83000");
harga.add("160000");
harga.add("14000");
harga.add("33000");
harga.add("17000");
harga.add("36000");
harga.add("6000");
for(int i=0; i<kode.size();i++) {
tabel.addRow(new Object[] {kode.get(i), namabarang.get(i), harga.get(i)});
}
Object[] baris = new Object[54];
table = new JTable();
scrollPane.setViewportView(table);
table.setModel(tabel);
/*{
boolean[] columnEditables = new boolean[] {
false, true
};
public boolean isCellEditable(int row, int column) {
return columnEditables[column];
}
}*/
table.setRowHeight(20);
table.getColumnModel().getColumn(0).setPreferredWidth(10);
table.getColumnModel().getColumn(1).setPreferredWidth(100);
table.getColumnModel().getColumn(2).setPreferredWidth(10);
JLabel lblKodeBarang = new JLabel("Kode Barang:");
lblKodeBarang.setForeground(Color.WHITE);
lblKodeBarang.setFont(new Font("Tahoma", Font.PLAIN, 14));
lblKodeBarang.setBounds(10, 65, 99, 22);
frame.getContentPane().add(lblKodeBarang);
tfKODE = new JTextField();
tfKODE.setFont(new Font("Tahoma", Font.PLAIN, 14));
tfKODE.setBounds(99, 62, 197, 29);
frame.getContentPane().add(tfKODE);
tfKODE.setColumns(10);
JButton btnCari = new JButton("Cari");
btnCari.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
try {
int cari = Integer.parseInt((String) tfKODE.getText());
for(int i=0; i<kode.size();i++) {
if(cari==Integer.parseInt(kode.get(i))) {
tfNAMA.setText(namabarang.get(i));
tfSATUAN.setText(harga.get(i));
}
}
}
catch(Exception e1) {
JOptionPane.showMessageDialog(null, "Masukkan kode barang yang benar!!");
tfKODE.setText("");
}
}
});
btnCari.setFont(new Font("Tahoma", Font.PLAIN, 14));
btnCari.setBounds(99, 96, 89, 23);
frame.getContentPane().add(btnCari);
JButton btnReset = new JButton("Reset");
btnReset.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
tfKODE.setText("");
tfNAMA.setText("");
tfSATUAN.setText("");
tfBANYAK.setText("");
tfTOTAL.setText("");
}
});
btnReset.setFont(new Font("Tahoma", Font.PLAIN, 14));
btnReset.setBounds(207, 96, 89, 23);
frame.getContentPane().add(btnReset);
JLabel lblNamaBarang = new JLabel("Nama Barang:");
lblNamaBarang.setForeground(Color.WHITE);
lblNamaBarang.setFont(new Font("Tahoma", Font.PLAIN, 14));
lblNamaBarang.setBounds(10, 130, 89, 22);
frame.getContentPane().add(lblNamaBarang);
tfNAMA = new JTextField();
tfNAMA.setFont(new Font("Tahoma", Font.PLAIN, 14));
tfNAMA.setEditable(false);
tfNAMA.setBounds(99, 129, 197, 29);
frame.getContentPane().add(tfNAMA);
tfNAMA.setColumns(10);
JLabel lblHarga = new JLabel("Harga Satuan:");
lblHarga.setForeground(Color.WHITE);
lblHarga.setFont(new Font("Tahoma", Font.PLAIN, 14));
lblHarga.setBounds(10, 170, 89, 22);
frame.getContentPane().add(lblHarga);
tfSATUAN = new JTextField();
tfSATUAN.setFont(new Font("Tahoma", Font.PLAIN, 14));
tfSATUAN.setEditable(false);
tfSATUAN.setBounds(99, 169, 197, 29);
frame.getContentPane().add(tfSATUAN);
tfSATUAN.setColumns(10);
JLabel lblNewLabel = new JLabel("Banyaknya:");
lblNewLabel.setForeground(Color.WHITE);
lblNewLabel.setFont(new Font("Tahoma", Font.PLAIN, 14));
lblNewLabel.setBounds(10, 209, 89, 22);
frame.getContentPane().add(lblNewLabel);
tfBANYAK = new JTextField();
tfBANYAK.setFont(new Font("Tahoma", Font.PLAIN, 14));
tfBANYAK.setBounds(99, 209, 197, 29);
frame.getContentPane().add(tfBANYAK);
tfBANYAK.setColumns(10);
JButton btnAdd = new JButton("Masuk Keranjang");
btnAdd.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
DefaultTableModel dt = (DefaultTableModel) tblKERANJANG.getModel();
Vector v = new Vector();
v.add(tfNAMA.getText());
v.add(tfTOTAL.getText());
dt.addRow(v);
/*int jumlahBaris = tblKERANJANG.getRowCount();
int totalBiaya = 0;
int hargaBarang=0;
for (int i=0; i<jumlahBaris; i++){
hargaBarang = Integer.parseInt(tblKERANJANG.getValueAt(i, 0).toString());
totalBiaya = totalBiaya + hargaBarang;
}
tfSUM.setText(String.valueOf(totalBiaya));*/
/*int total = 0;
for (int i = 0; i <tblKERANJANG.getRowCount(); i++) {
int amount = Integer.parseInt((String) tblKERANJANG.getValueAt(i, 1));
total += amount;
}
tfSUM.setText(String.valueOf(total));*/
}
});
/*btnAdd.addMouseListener(new MouseAdapter() {
@Override
public void mouseClicked(MouseEvent arg0) {
DefaultTableModel dataModel = (DefaultTableModel) tblKERANJANG.getModel();
List list = new ArrayList<>();
tblKERANJANG.setAutoCreateColumnsFromModel(true);
list.add(tfNAMA.getText());
list.add(tfBANYAK.getText());
list.add(tfTOTAL.getText());
dataModel.addRow(list.toArray());
//sum();
/*int jumlahBaris = tblKERANJANG.getRowCount();
int totalBiaya = 0;
int jumlahBarang, hargaBarang;
TableModel tabelModel;
tabelModel = tblKERANJANG.getModel();
for (int i=0; i<jumlahBaris; i++){
jumlahBarang = Integer.parseInt(tabelModel.getValueAt(i, 2).toString());
hargaBarang = Integer.parseInt(tabelModel.getValueAt(i, 3).toString());
totalBiaya = totalBiaya + (jumlahBarang*hargaBarang);
}
tfSUM.setText(String.valueOf(totalBiaya));
}*/
//});
btnAdd.setFont(new Font("Tahoma", Font.PLAIN, 14));
btnAdd.setBounds(124, 325, 150, 29);
frame.getContentPane().add(btnAdd);
JLabel lblTotal = new JLabel("Total:");
lblTotal.setForeground(Color.WHITE);
lblTotal.setFont(new Font("Tahoma", Font.PLAIN, 14));
lblTotal.setBounds(10, 290, 89, 22);
frame.getContentPane().add(lblTotal);
tfTOTAL = new JTextField();
tfTOTAL.setFont(new Font("Tahoma", Font.PLAIN, 14));
tfTOTAL.setEditable(false);
tfTOTAL.setBounds(99, 289, 197, 29);
frame.getContentPane().add(tfTOTAL);
tfTOTAL.setColumns(10);
btnHitung.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
try {
int a, b, hasiltotal;
a=Integer.parseInt(tfSATUAN.getText());
b=Integer.parseInt(tfBANYAK.getText());
//a=Double.parseDouble(tfSATUAN.getText());
//b=Double.parseDouble(tfBANYAK.getText());
hasiltotal = a*b;
tfTOTAL.setText(Integer.toString(hasiltotal));
}
catch(Exception e1) {
JOptionPane.showMessageDialog(null, "Inputan Salah!!");
tfBANYAK.setText("");
tfTOTAL.setText("");
}
}
});
btnHitung.setFont(new Font("Tahoma", Font.PLAIN, 14));
btnHitung.setBounds(124, 249, 150, 29);
frame.getContentPane().add(btnHitung);
JButton btnBATAL = new JButton("Batal");
btnBATAL.addMouseListener(new MouseAdapter() {
@Override
public void mouseClicked(MouseEvent arg0) {
try {
DefaultTableModel dataModel = (DefaultTableModel) tblKERANJANG.getModel();
if (tblKERANJANG.getRowCount() > 0) {
for (int i = tblKERANJANG.getRowCount() - 1; i > -1; i--) {
dataModel.removeRow(i);
}
}
}
catch(Exception e1) {
JOptionPane.showMessageDialog(null, "Tidak ada daftar pada keranjang!");
tfKODE.setText("");
}
}
});
btnBATAL.setFont(new Font("Tahoma", Font.PLAIN, 14));
btnBATAL.setBounds(114, 527, 89, 23);
frame.getContentPane().add(btnBATAL);
JButton btnX = new JButton("X");
btnX.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
int s= JOptionPane.showConfirmDialog(null, "Apakah anda ingin menutup program? ");
if(s==JOptionPane.YES_OPTION)
{System.exit(0);
}
}
});
btnX.setFont(new Font("Tahoma", Font.PLAIN, 18));
btnX.setBounds(731, 16, 50, 35);
frame.getContentPane().add(btnX);
tfSUM = new JTextField();
tfSUM.setEditable(false);
tfSUM.setBounds(400, 370, 185, 29);
frame.getContentPane().add(tfSUM);
tfSUM.setColumns(10);
JLabel label = new JLabel("");
label.setIcon(new ImageIcon("C:\\Users\\LENOVO\\eclipse-workspace\\2018Etugasakhir\\STATIONARY4.png"));
label.setBounds(0, 0, 800, 560);
frame.getContentPane().add(label);
}
private void btnHitungActionPerformed(java.awt.event.ActionEvent evt) {//GEN-FIRST:event_btnHitungActionPerformed
// TODO add your handling code here:
int jumlahBaris = tblKERANJANG.getRowCount();
int totalBiaya = 0;
int jumlahBarang, hargaBarang;
TableModel tabelModel;
tabelModel = tblKERANJANG.getModel();
for (int i=0; i<jumlahBaris; i++){
jumlahBarang = Integer.parseInt(tabelModel.getValueAt(i, 1).toString());
totalBiaya = totalBiaya + (jumlahBarang);
}
tfSUM.setText(String.valueOf(totalBiaya));
}//GEN-LAST:event_btnHitungActionPerformed
}
当我运行这个程序时，它运行得很顺利，很符合要求 但是当我点击 "TOTAL "按钮时，我得到了这个错误。
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at BismillahKasir2.btnHitungActionPerformed(BismillahKasir2.java:617)
at BismillahKasir2.access$1(BismillahKasir2.java:609)
at BismillahKasir2$2.actionPerformed(BismillahKasir2.java:98)
at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)
at javax.swing.AbstractButton$Handler.actionPerformed(Unknown Source)
at javax.swing.DefaultButtonModel.fireActionPerformed(Unknown Source)
at javax.swing.DefaultButtonModel.setPressed(Unknown Source)
at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(Unknown Source)
at java.awt.Component.processMouseEvent(Unknown Source)
at javax.swing.JComponent.processMouseEvent(Unknown Source)
at java.awt.Component.processEvent(Unknown Source)
at java.awt.Container.processEvent(Unknown Source)
at java.awt.Component.dispatchEventImpl(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Window.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
at java.awt.EventQueue.access$500(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(Unknown Source)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue$4.run(Unknown Source)
at java.awt.EventQueue$4.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at BismillahKasir2.btnHitungActionPerformed(BismillahKasir2.java:617)
at BismillahKasir2.access$1(BismillahKasir2.java:609)
at BismillahKasir2$2.actionPerformed(BismillahKasir2.java:98)
at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)
at javax.swing.AbstractButton$Handler.actionPerformed(Unknown Source)
at javax.swing.DefaultButtonModel.fireActionPerformed(Unknown Source)
at javax.swing.DefaultButtonModel.setPressed(Unknown Source)
at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(Unknown Source)
at java.awt.Component.processMouseEvent(Unknown Source)
at javax.swing.JComponent.processMouseEvent(Unknown Source)
at java.awt.Component.processEvent(Unknown Source)
at java.awt.Container.processEvent(Unknown Source)
at java.awt.Component.dispatchEventImpl(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Window.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
at java.awt.EventQueue.access$500(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(Unknown Source)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue$4.run(Unknown Source)
at java.awt.EventQueue$4.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)
请帮助我，我对java不了解，谢谢。
我不知道这是否破坏了什么，但在你的for循环中，我把'i = 0'改成了'i = 1'，一切都没有错误。我想这是因为你的jTable中的第一个值是一个字符串。
private void btnHitungActionPerformed(java.awt.event.ActionEvent evt) {//GEN-FIRST:event_btnHitungActionPerformed
// TODO add your handling code here:
int jumlahBaris = tblKERANJANG.getRowCount();
int totalBiaya = 0;
int jumlahBarang, hargaBarang;
TableModel tabelModel;
tabelModel = tblKERANJANG.getModel();
for (int i=1; i<jumlahBaris; i++){
jumlahBarang = Integer.parseInt(tabelModel.getValueAt(i, 1).toString());
totalBiaya = totalBiaya + (jumlahBarang);
}
tfSUM.setText(String.valueOf(totalBiaya));
}//GEN-LAST:event_btnHitungActionPerformed