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How to update Jtable immediately or automtically when I press a button

I have created a JTable with some information about formula 1 racing car drivers. The below code is for the JTable
import java.awt.LayoutManager;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.table.AbstractTableModel;
import java.awt.event.*;
public class Test1 extends JFrame implements ActionListener {
JButton button;
Test1() {
//setBounds(100, 100, 500, 400);
JFrame frame = new JFrame();
button = new JButton();
//button.setBounds(50, 50, 20, 10);s
button.setText("Random Race");
button.addActionListener(this);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JTable table = new JTable(new Model1Data());
frame.setBounds(100, 100, 500, 400);
JPanel panel = new JPanel();
frame.add(panel);
panel.add(new JScrollPane(table));
panel.add(button);
//add(new J
frame.setVisible(true);
//this.add(button);
pack();
}
#Override
public void actionPerformed(ActionEvent e) {
Formula1ChampionsManager d= new Formula1ChampionsManager();
d.button();
}
}
This is the code for the Model1Data. This is the code for the table to update its cells.
import javax.swing.table.AbstractTableModel;
public class Model1Data extends AbstractTableModel implements ChampionsManager {
String colNames[] = { "Name", "Team", "No of first Places", "Total Points" };
Class<?> colClasses[] = { String.class, String.class, Integer.class, Integer.class };
public int getRowCount() {
return myDrivers.size();
}
public int getColumnCount() {
return colNames.length;
}
public Object getValueAt(int rowIndex, int columnIndex) {
if (columnIndex == 0) {
return myDrivers.get(rowIndex).getName();
}
if (columnIndex == 1) {
return myDrivers.get(rowIndex).getTeam();
}
if (columnIndex == 2) {
return myDrivers.get(rowIndex).getfirstPlace();
}
if (columnIndex == 3) {
return myDrivers.get(rowIndex).totalPoints();
}
return null;
}
public String getColumnName(int columnIndex) {
return colNames[columnIndex];
}
public Class<?> getColumnClass(int columnIndex) {
return colClasses[columnIndex];
}
public boolean isCellEditable(int rowIndex, int columnIndex) {
return false;
}
public void setValueAt(Object aValue, int rowIndex, int columnIndex) {
if (columnIndex == 0) {
myDrivers.get(rowIndex).setName((String) aValue);
}
if (columnIndex == 1) {
myDrivers.get(rowIndex).setTeam((String) aValue);
}
if (columnIndex == 2) {
myDrivers.get(rowIndex).setfirstPlace((Integer) aValue);
}
if (columnIndex == 3) {
myDrivers.get(rowIndex).settotalPoints((Integer) aValue);
}
//fireTableCellUpdated(rowIndex, columnIndex);
}
}
This what the table GUI looks like Table GUI. When I click the button the values for No of first places and Total Points are changed randomly. But the table doesn't get updated with the values. If I pull on the side of the frame it gets updated. How do I get it to update when I click the button?

The JTable listens for changes in the TableModel. Hence class AbstractTableModel has methods such as fireTableCellUpdated(rowIndex, columnIndex) (which you commented out in your code - why?). If you override method setValueAt then you need to call that method, otherwise the JTable will not update when its data is changed. I'm guessing that changing the size of the JFrame causes a repaint of the JTable which causes the JTable to reload the data from its model (but I could be wrong).
Your class Model1Data should extend DefaultTableModel, rather than AbstractTableModel, since that class already contains all the functionality you require. The only method that class Model1Data needs to override is getColumnClass (which it already does). You also need to override at least one constructor. Since you didn't post a minimal, reproducible example, I'm guessing that this constructor may be appropriate. Hence the code for class Model1Data should be:
public class Model1Data extends javax.swing.table.DefaultTableModel {
Class<?> colClasses[] = { String.class, String.class, Integer.class, Integer.class };
public Model1Data(Object[] columnNames, int rowCount) {
super(columnNames, rowCount);
}
public Class<?> getColumnClass(int columnIndex) {
return colClasses[columnIndex];
}
}
And in class Test1 (which does not need to extend JFrame, by the way) you can create the JTable like so:
JTable table = new JTable(new Model1Data(new String[]{ "Name", "Team", "No of first Places", "Total Points" }, 0));
Edit
Here's my take on what you are trying to do. The below code can be copied as is, compiled and run. Just click on the Random Race button and the data in the JTable will update.
import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Objects;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.table.DefaultTableModel;
import javax.swing.table.TableModel;
public class Test1 {
private JTable table;
private void buildAndDisplayGui() {
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(createTable(), BorderLayout.CENTER);
frame.add(createButtonsPanel(), BorderLayout.PAGE_END);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
private JButton createButton(String text, int mnemonic, ActionListener listener) {
JButton button = new JButton(text);
button.setMnemonic(mnemonic);
button.addActionListener(listener);
return button;
}
private JPanel createButtonsPanel() {
JPanel buttonsPanel = new JPanel();
buttonsPanel.add(createButton("Random Race", KeyEvent.VK_R, this::randomRace));
return buttonsPanel;
}
private JScrollPane createTable() {
table = new JTable(new Model1Data());
table.setAutoResizeMode(JTable.AUTO_RESIZE_OFF);
JScrollPane scrollPane = new JScrollPane(table);
return scrollPane;
}
/**
* Simulates a race and randomly determines placings of the drivers and assigns appropriate
* points scores.
*
* #param event - encapsulates button press event
*/
private void randomRace(ActionEvent event) {
Formula1ChampionsManager.simulate();
TableModel tm = table.getModel();
if (tm instanceof Model1Data) {
Model1Data model = (Model1Data) tm;
model.setRowCount(0);
model.init();
}
}
public static void main(String[] args) {
EventQueue.invokeLater(() -> {
new Test1().buildAndDisplayGui();
});
}
}
class Model1Data extends DefaultTableModel {
private static final String[] COLUMN_NAMES = {"Name", "Team", "No of first Places", "Total Points"};
public Model1Data() {
super(COLUMN_NAMES, 0);
init();
}
public void addDriver(F1Driver driver) {
addRow(new Object[]{driver.getName(),
driver.getTeam(),
driver.getFirstPlace(),
driver.getTotalPoints()});
}
public void init() {
Formula1ChampionsManager.getDrivers()
.stream()
.forEach(this::addDriver);
}
}
class Formula1ChampionsManager {
private static List<F1Driver> drivers;
static {
drivers = List.of(new F1Driver("Lewis Hamilton", F1Teams.MERCEDES),
new F1Driver("Max Verstappen",F1Teams.RED_BULL),
new F1Driver("Charles Leclerc",F1Teams.FERRARI),
new F1Driver("Lando Norris",F1Teams.MCLAREN),
new F1Driver("Fernando Alonso",F1Teams.ALPINE),
new F1Driver("Pierre Gasly",F1Teams.ALPHATAURI),
new F1Driver("Sebastian Vettel",F1Teams.ASTON_MARTIN),
new F1Driver("Nicholas Latifi",F1Teams.WILLIAMS),
new F1Driver("Valtteri Bottas",F1Teams.ALFA_ROMEO),
new F1Driver("Mick Schumacher",F1Teams.HAAS));
}
public static List<F1Driver> getDrivers() {
return drivers;
}
public static void simulate() {
List<F1Driver> result = new ArrayList<>(drivers);
Collections.shuffle(result);
F1Driver first = result.get(0);
first.update(F1Driver.FIRST);
F1Driver second = result.get(1);
second.update(F1Driver.SECOND);
F1Driver third = result.get(2);
third.update(F1Driver.THIRD);
F1Driver fourth = result.get(3);
fourth.update(F1Driver.FOURTH);
F1Driver fifth = result.get(4);
fifth.update(F1Driver.FIFTH);
F1Driver sixth = result.get(5);
sixth.update(F1Driver.SIXTH);
F1Driver seventh = result.get(6);
seventh.update(F1Driver.SEVENTH);
F1Driver eighth = result.get(7);
eighth.update(F1Driver.EIGHTH);
F1Driver ninth = result.get(8);
ninth.update(F1Driver.NINTH);
F1Driver tenth = result.get(9);
tenth.update(F1Driver.TENTH);
}
}
enum F1Teams {
MERCEDES("Mercedes"),
RED_BULL("Red Bull"),
FERRARI("Ferrari"),
MCLAREN("McLaren"),
ALPINE("Alpine"),
ALPHATAURI("AlphaTauri"),
ASTON_MARTIN("Aston Martin"),
WILLIAMS("Williams"),
ALFA_ROMEO("Alfa Romeo"),
HAAS("Haas");
private String name;
private F1Teams(String name) {
this.name = name;
}
#Override // java.lang.Enum
public String toString() {
return name;
}
}
class F1Driver {
public static final int FIRST = 25;
public static final int SECOND = 18;
public static final int THIRD = 15;
public static final int FOURTH = 12;
public static final int FIFTH = 10;
public static final int SIXTH = 8;
public static final int SEVENTH = 6;
public static final int EIGHTH = 4;
public static final int NINTH = 2;
public static final int TENTH = 1;
private String name;
private F1Teams team;
private int firstPlace;
private int totalPoints;
public F1Driver(String name, F1Teams team) {
this(name, team, 0, 0);
}
public F1Driver(String name, F1Teams team, int firstPlace, int totalPoints) {
Objects.requireNonNull(name, "Missing name.");
this.name = name;
this.team = team;
this.firstPlace = firstPlace;
this.totalPoints = totalPoints;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public F1Teams getTeam() {
return team;
}
public void setTeam(F1Teams team) {
this.team = team;
}
public int getFirstPlace() {
return firstPlace;
}
public void setFirstPlace(int firstPlace) {
this.firstPlace = firstPlace;
}
public int getTotalPoints() {
return totalPoints;
}
public void setTotalPoints(int totalPoints) {
this.totalPoints = totalPoints;
}
#Override // java.lang.Object
public boolean equals(Object obj) {
boolean equal = this == obj;
if (!equal) {
if (obj instanceof F1Driver) {
F1Driver other = (F1Driver) obj;
equal = name != null &&
name.equals(other.name) &&
team == other.team;
}
}
return equal;
}
#Override // java.lang.Object
public int hashCode() {
return (String.valueOf(name) + String.valueOf(team)).hashCode();
}
#Override // java.lang.Object
public String toString() {
return String.format("%s [%s] %d [%d]", name, team, totalPoints, firstPlace);
}
public void update(int points) {
totalPoints += points;
if (points == FIRST) {
firstPlace++;
}
}
}
Here's how it looks when I run the above code.

How do I make it possible to select text in a JTable cell with editing disabled?

Imagine I'm building an IRC client with Java and I'd like rich text in the chat view to show IRC colors and colored nicks. I'd like to build this with a JTable. I can do that, but the text is then not selectable. Making the table editable doesn't make sense.
I've also investigated:
TextArea - no rich text formatting
JEditPane - can't append, only replace which is bad performance wise
JList - can't select text
So I got a table working I just need the text to be selectable without making it editable. I'd also would only like the text contents, and none of the HTML to be copied into the clipboard upon copying the text selection.
I have tried various iterations of setRowSelectionAllowed(), setColumnSelectionEnabled() and setCellSelectionEnabled() and setSelectionMode the table model returns false for isCellEditable(). Nothing has made the text selectable.
EDIT: as per answer 1 I was wrong about text editor panes so I'm trying those solutions.

I don't know why you don't want to use a JTextPane or JEditorPane. You insert text by its document. Examples here --> How to use Editor Panes and Text Panes.
But for your purpose you can for example do something like this. I override changeSelection to selectAll text when is clicking, the cells are editable but its cellEditors are not editable.
public class JTableTest {
private final DefaultCellEditor cellEditor;
private final JTextField textfield;
private JPanel panel;
private MyTableModel tableModel = new MyTableModel();
private JTable table = new JTable() {
#Override
public TableCellEditor getCellEditor(int row, int column) {
return JTableTest.this.cellEditor;
}
#Override
public void changeSelection(
final int row, final int column, final boolean toggle, final boolean extend) {
super.changeSelection(row, column, toggle, extend);
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
if ((getCellEditor(row, column) != null && !editCellAt(row, column))) {
JTextField textfield=(JTextField)JTableTest.this.cellEditor.getComponent();
textfield.selectAll();
}
}
});
}
};
public JTableTest() {
JScrollPane scroll = new JScrollPane(table);
table.setModel(tableModel);
panel = new JPanel(new BorderLayout());
panel.add(scroll, BorderLayout.CENTER);
textfield = new JTextField();
textfield.setEditable(Boolean.FALSE);
textfield.setBorder(null);
cellEditor = new DefaultCellEditor(textfield);
tableModel.insertValue(new ItemRow("nonEditable", "Editable"));
}
private class ItemRow {
private String column1;
private String column2;
public ItemRow(String column1, String column2) {
this.column1 = column1;
this.column2 = column2;
}
public String getColumn1() {
return column1;
}
public void setColumn1(String column1) {
this.column1 = column1;
}
public String getColumn2() {
return column2;
}
public void setColumn2(String column2) {
this.column2 = column2;
}
}
private class MyTableModel extends AbstractTableModel {
public static final int COLUMN1_INDEX = 0;
public static final int COLUMN2_INDEX = 1;
private final List<ItemRow> data = new ArrayList<>();
private final String[] columnsNames = {
"Column1",
"Column2",};
private final Class<?>[] columnsTypes = {
String.class,
String.class
};
public MyTableModel() {
super();
}
#Override
public Object getValueAt(int inRow, int inCol) {
ItemRow row = data.get(inRow);
Object outReturn = null;
switch (inCol) {
case COLUMN1_INDEX:
outReturn = row.getColumn1();
break;
case COLUMN2_INDEX:
outReturn = row.getColumn2();
break;
default:
throw new RuntimeException("invalid column");
}
return outReturn;
}
#Override
public void setValueAt(Object inValue, int inRow, int inCol) {
System.out.println("Gets called ");
if (inRow < 0 || inCol < 0 || inRow >= data.size()) {
return;
}
ItemRow row = data.get(inRow);
switch (inCol) {
case COLUMN1_INDEX:
row.setColumn1(inValue.toString());
break;
case COLUMN2_INDEX:
row.setColumn2(inValue.toString());
break;
}
fireTableCellUpdated(inRow, inCol);
}
#Override
public int getRowCount() {
return data.size();
}
#Override
public int getColumnCount() {
return columnsTypes.length;
}
#Override
public String getColumnName(int inCol) {
return this.columnsNames[inCol];
}
#Override
public Class<?> getColumnClass(int columnIndex) {
return this.columnsTypes[columnIndex];
}
/**
*
* #param row
*/
public void insertValue(ItemRow row) {
data.add(row);
fireTableRowsInserted(data.size() - 1, data.size() - 1);
}
#Override
public boolean isCellEditable(int rowIndex, int columnIndex) {
return true;
}
}
private static void createAndShowGUI(final Container container, final String title) {
//Create and set up the window.
JFrame frame = new JFrame(title);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLocationByPlatform(Boolean.TRUE);
frame.add(container);
//Display the window.
frame.pack();
frame.setVisible(true);
}
public static void main(String args[]) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
createAndShowGUI(new JTableTest().panel, "Test");
}
});
}
}

I accomplished this by enabling the editing and then making the component responsible for the edition ignore any changes. For this I created a TableCellEditor and intercepted the key types to the JTextField, the component used for editing.
import java.awt.BorderLayout;
import java.awt.Component;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
import javax.swing.AbstractCellEditor;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;
import javax.swing.table.DefaultTableCellRenderer;
import javax.swing.table.DefaultTableModel;
import javax.swing.table.TableCellEditor;
public class TableCellSelectionTest
{
public static void main(String[] args)
{
SwingUtilities.invokeLater(new Runnable() {
public void run()
{
new TableCellSelectionTest().initUI();
}
});
}
public void initUI()
{
JFrame frame = new JFrame();
int N = 5;
int M = 3;
Object[][] data = new Object[N][M];
for (int i = 0; i < N; ++i)
{
for (int j = 0; j < M; ++j)
{
data[i][j] = "This is the cell (" + i + ", " + j +")";
}
}
String[] columnNames = { "Column 1", "Column 2", "Column 3" };
DefaultTableModel model = new DefaultTableModel(data, columnNames);
final MyTableCellEditor editor = new MyTableCellEditor();
JTable table = new JTable(model) {
#Override
public TableCellEditor getCellEditor(int row, int column)
{
return editor;
}
};
frame.add(new JScrollPane(table), BorderLayout.CENTER);
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
class MyTableCellEditor extends AbstractCellEditor implements
TableCellEditor
{
Object _value;
#Override
public Object getCellEditorValue()
{
return _value;
}
#Override
public Component getTableCellEditorComponent(JTable table,
Object value, boolean isSelected, int row, int column)
{
_value = value;
JTextField textField = new JTextField(_value.toString());
textField.addKeyListener(new KeyAdapter()
{
public void keyTyped(KeyEvent e) {
e.consume(); //ignores the key
}
#Override
public void keyPressed(KeyEvent e)
{
e.consume();
}});
textField.setEditable(false); //this is functionally irrelevent, makes slight visual changes
return textField;
}
}
}

I tried both the answers here... but one problem at least is that you can tell when you've entered the "editing" mode.
This might be of interest... uses a combination of Editor magic and cheeky rendering to make it look like no editing is going on: editor's click-count-to-start is set to 1, and the component (JTextPane) delivered by the editor's method does setEditable( false ).
If this tickles your fancy, you might be interested at looking at my implementation of a JTable which adjusts (perfectly, harnessing the JTextPane's powerful wrapping power) the row height to the text, for individual rows, including when you change the columns: How to wrap lines in a jtable cell?
public class SelectableNonEditableTableTest {
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
JFrame main_frame = new JFrame();
main_frame.setPreferredSize(new Dimension(1200, 300));
main_frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
ArrayList<String> nonsense = new ArrayList<String>(
Arrays.asList(
"Lorem ipsum dolor sit amet, sed dolore vivendum ut",
"pri an soleat causae doctus.",
"Alienum abhorreant mea ea",
"cum malorum diceret ei. Pri oratio invidunt consequat ne.",
"Ius tritani detraxit scribentur et",
"has detraxit legendos intellegat at",
"quo oporteat constituam ex"));
JTable example_table = new JTable(10, 4);
example_table.setRowHeight( example_table.getRowHeight() * 2 );
DefaultCellEditor cell_editor = new SelectableNonEditableCellEditor(
new JTextField());
cell_editor.setClickCountToStart(1);
example_table.setDefaultEditor(Object.class, cell_editor);
TableCellRenderer renderer = new SelectableNonEditableTableRenderer();
example_table.setDefaultRenderer(Object.class, renderer);
for (int i = 0; i < 10; i++) {
example_table.setValueAt(nonsense.get(i % nonsense.size()),
i, i % 4);
}
main_frame.getContentPane().add(new JScrollPane(example_table));
main_frame.pack();
main_frame.setVisible(true);
}
});
}
}
class SelectableNonEditableCellEditor extends DefaultCellEditor {
public SelectableNonEditableCellEditor(JTextField textField) {
super(textField);
}
public Component getTableCellEditorComponent(JTable table, Object value,
boolean isSelected, int row, int col) {
Component comp = super.getTableCellEditorComponent(table, value,
isSelected, row, col);
if (value instanceof java.lang.String) {
DefaultStyledDocument sty_doc = new DefaultStyledDocument();
try {
sty_doc.insertString(0, (String) value, null);
} catch (BadLocationException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
JTextPane jtp_comp = new JTextPane(sty_doc);
jtp_comp.setEditable(false);
return jtp_comp;
}
return comp;
}
}
class SelectableNonEditableTableRenderer extends JTextPane implements
TableCellRenderer {
#Override
public Component getTableCellRendererComponent(JTable table, Object value,
boolean isSelected, boolean hasFocus, int row, int column) {
if (value instanceof DefaultStyledDocument) {
setDocument((DefaultStyledDocument) value);
} else {
setText((String) value);
}
return this;
}
}

Maybe you can implement your own TableCellRenderer that extends JTextField in your table.

GUI Not working with custom AbstractTableModel. Errors "Unknown Source"

I am currently creating, or more trying to create the GUI for my project. What I need to do now, is create a JTable that reads the data from a LinkedList. I have a custom TableAbstractModel for this.
public class StudentTableModel extends AbstractTableModel {
public static final String[] columnNames = { "ID", "First Name",
"Last Name" };
private LinkedList<Student> data;
public StudentTableModel(LinkedList<Student> data) {
this.data = data;
}
#Override
public int getColumnCount() {
return columnNames.length;
}
#Override
public String getColumnName(int column) {
return columnNames[column];
}
#Override
public int getRowCount() {
return data.size();
}
#Override
public Object getValueAt(int rowIndex, int columnIndex) {
Student student = data.get(rowIndex);
if (student == null) {
return null;
}
switch (columnIndex) {
case 0:
return student.getID();
case 1:
return student.getFirstname();
case 2:
return student.getLastname();
default:
return null;
}
}
}
Now I was trying to build a very basic layout consisting just of the table, and the appropriate JTextfields and JButtons to test if the table actually works.
public class GUI extends JFrame {
private JTextField StudentID;
private JTextField Firstname;
private JTextField Lastname;
private JTextField Group;
private JButton Add;
private static Database DB; // << Does this have to be static? Eclipse tells me it needs to be, but I am not sure.
private JTable StudentTable;
public GUI(Database DB) {
super("Theatre Management");
setExtendedState(JFrame.MAXIMIZED_BOTH);
this.DB = DB;
LinkedList<Student> data = null;
setLayout(new FlowLayout());
StudentID = new JTextField("Enter Student ID", 10);
Firstname = new JTextField("Enter First Name");
Lastname = new JTextField("Enter Last Name");
Group = new JTextField("Enter Group ID");
Add = new JButton("Add Student");
StudentTable = new JTable();
StudentTable.setModel(new StudentTableModel(data));
JScrollPane scrollPane = new JScrollPane(StudentTable);
StudentTable.setFillsViewportHeight(true);
add(StudentTable);
add(StudentID);
add(Firstname);
add(Lastname);
add(Group);
add(Add);
add(scrollPane);
addStudentEvent add = new addStudentEvent();
Add.addActionListener(add);
}
public static void createAndShow() {
GUI Database = new GUI(DB);
Database.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
Database.setVisible(true);
}
public static void main(String[] args) {
GUI.createAndShow();
}
private class addStudentEvent implements ActionListener {
public void actionPerformed(ActionEvent event) {
int G = Integer.parseInt(Group.getText());
int ID = Integer.parseInt(StudentID.getText());
String First = Firstname.getText();
String Last = Lastname.getText();
DB.getGroup(G).addStudent(ID, First, Last);
DB.addStudent(ID, First, Last);
}
}
}
Now, the problem is, as soon as I try to run the GUI, I just get a whole bunch of errors.
Exception in thread "main" java.lang.NullPointerException
at theatremanagement.StudentTableModel.getRowCount(StudentTableModel.java:29)
at javax.swing.JTable.getRowCount(Unknown Source)
at javax.swing.plaf.basic.BasicTableUI.createTableSize(Unknown Source)
at javax.swing.plaf.basic.BasicTableUI.getPreferredSize(Unknown Source)
at javax.swing.JComponent.getPreferredSize(Unknown Source)
at java.awt.FlowLayout.layoutContainer(Unknown Source)
at java.awt.Container.layout(Unknown Source)
at java.awt.Container.doLayout(Unknown Source)
at java.awt.Container.validateTree(Unknown Source)
at java.awt.Container.validateTree(Unknown Source)
at java.awt.Container.validateTree(Unknown Source)
at java.awt.Container.validateTree(Unknown Source)
at java.awt.Container.validate(Unknown Source)
at java.awt.Container.validateUnconditionally(Unknown Source)
at java.awt.Window.show(Unknown Source)
at java.awt.Component.show(Unknown Source)
at java.awt.Component.setVisible(Unknown Source)
at java.awt.Window.setVisible(Unknown Source)
at theatremanagement.GUI.createAndShow(GUI.java:59)
at theatremanagement.GUI.main(GUI.java:64)
I am really stuck right now and have no clue how to fix that. If anybody could show me what I am doing wrong, that would be great. On other thing, I have to LinkedList in my program, in different classes. How does the TableModel know which one I want? Do I need to add anything to the TableModel, to make the table automatically update as soon as a add or delete a student?
Update:
private JTable setStudentList(LinkedList<Student> Studentlist) {
JTable StudentTable = new JTable();
StudentTable.setModel(new StudentTableModel(Studentlist));
JScrollPane scrollPane = new JScrollPane(StudentTable);
StudentTable.setFillsViewportHeight(true);
return StudentTable;
Does this method work to create the table with the linked list? Would I then call for the method as
setStudentList(Studentlist);
If I initiliazed an empty LinkedList as such:
LinkedList<Student> StudentList = new LinkedList<Student>();
Thanks for the help.

The LinkedList is never initalised...
LinkedList<Student> data = null;
// ... ///
StudentTable.setModel(new StudentTableModel(data));
Meaning that when getRowCount is called, the data object is null, hence the NullPointerException
Updated
You have any number of options that you can use to pass a reference to main LinkedList into the UI, but it will come down to how your work flow works.
You could...
Pass the reference to the UI via it's constructor....
public GUI(Database DB, LinkedList<Student> students) {...}
You could...
Pass the LinkedList in via a method in you GUI class...
public class GUI extends JFrame {
//...//
public GUI(Database DB) {...}
public void setStudent(LinkedList<Student> students) {
StudentTable.setModel(new StudentTableModel(students));
}
}
Updated with example
import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.LinkedList;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
import javax.swing.table.AbstractTableModel;
public class PassTable {
public static void main(String[] args) {
new PassTable();
}
public PassTable() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
}
JFrame frame = new JFrame("Test");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new BorderLayout());
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
private ExampleTable example;
public TestPane() {
setLayout(new BorderLayout());
example = new ExampleTable();
add(example);
JButton add = new JButton("Add");
add(add, BorderLayout.SOUTH);
add.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
LinkedList<Person> people = new LinkedList<Person>();
people.add(new Person("A", "A", 1));
people.add(new Person("B", "B", 2));
people.add(new Person("C", "C", 3));
people.add(new Person("D", "D", 4));
example.setPeople(people);
}
});
}
}
public class ExampleTable extends JPanel {
private JTable table;
public ExampleTable() {
this(new LinkedList<Person>());
}
public ExampleTable(LinkedList<Person> people) {
setLayout(new BorderLayout());
table = new JTable(new SampleTableModel(people));
add(new JScrollPane(table));
}
public void setPeople(LinkedList<Person> people) {
table.setModel(new SampleTableModel(people));
}
}
public class SampleTableModel extends AbstractTableModel {
private LinkedList<Person> data;
public SampleTableModel(LinkedList<Person> data) {
this.data = data;
}
#Override
public int getRowCount() {
return data.size();
}
#Override
public String getColumnName(int column) {
String name = "";
switch (column) {
case 0:
name = "First name";
break;
case 1:
name = "Last name";
break;
case 2:
name = "Age";
break;
}
return name;
}
#Override
public int getColumnCount() {
return 3;
}
#Override
public Object getValueAt(int rowIndex, int columnIndex) {
Object value = null;
Person person = data.get(rowIndex);
switch (columnIndex) {
case 0:
value = person.getFirstName();
break;
case 1:
value = person.getLastName();
break;
case 2:
value = person.getAge();
break;
}
return value;
}
}
public class Person {
private String firstName;
private String lastName;
private int age;
public Person(String firstName, String lastName, int age) {
this.firstName = firstName;
this.lastName = lastName;
this.age = age;
}
public int getAge() {
return age;
}
public String getFirstName() {
return firstName;
}
public String getLastName() {
return lastName;
}
}
}

java: Get row data from popupmenu actionListener event

I'm having a little scenario here that maybe a duplicate. I have JTable where i show some data, i have a mouselistener that listens for right clicks on the table and displays a popup menu with one menuitem. My goal is that when the user clicks the menuitem, i get the values from the table and feed them into a custom dialog which has some fill in fields, so that the user doesn't have to feed the whole dialog by hand since i will feed the dialog with the values selected on the table. but my problem is that the menuitem actionevent doesn't have a way of getting the point so that i can use table.getRowAt(). i have read another comment (check here https://stackoverflow.com/a/4122082/1788917) where i have been told that i can save the row number in a variable that can then be accessed by the actionlistener for the menuitem.
i want it to look like this
theScrollPane.getViewport().add(myJTable, null);
JMenuItem menuItem = new JMenuItem(clickMe);
menuItem.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
menuItemActionPerformed(e);
}
});
MouseListener popupListener = new PopupListener();
popupMenu.add(menuItem);
myJTable.addMouseListener(popupListener);
protected void menuItemActionPerformed (ActionEvent e) {
// what to do here to get the table row data
// and send it to my custom dialog via it's constructor ???
}
// a simple nested class for the popup
class PopupListener extends MouseAdapter {
public void mousePressed(MouseEvent e) {
int row = myJTable.rowAtPoint(e.getPoint());
int selectedRow = myJTable.getSelectedRow();
// just to make sure the popup appears only where the row is
// selected
if (row == selectedRow) {
showPopup(e);
}
}
public void mouseReleased(MouseEvent e) {
int row = myJTable.rowAtPoint(e.getPoint());
int selectedRow = myJTable.getSelectedRow();
if (row == selectedRow) {
showPopup(e);
}
}
private void showPopup(MouseEvent e) {
if (e.isPopupTrigger()) {
popupMenu.show(e.getComponent(), e.getX(), e.getY());
}
}
}
so my question is, is saving the row number the only way that i can do this or is there a better way?

i have read another comment (check here https://stackoverflow.com/a/4122082/1788917) where i have been told that i can save the row number in a variable
You read the wrong comment.
If you read the answer above that link (ie. the one with 7 votes) you will see the solution is to select the row you clicked on BEFORE showing the popup menu. Then in your menu item Action you can reference
table.getSelectedRow();

I have tried your case referring to this case and I am able to get the row and show it in a JDialog. I just modified my old code to do this. I haven't thoroughly tested.
import java.awt.EventQueue;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.util.ArrayList;
import java.util.List;
import javax.swing.JDialog;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTabbedPane;
import javax.swing.JTable;
import javax.swing.table.AbstractTableModel;
public class AllTableExample {
private JTabbedPane tabbedPane;
private JTable allTable;
private AllTableModel allTableModel;
public AllTableExample() {
List<TableData> data = new ArrayList<TableData>();
data.add(new TableData("John1", "A", "Maths", "Hellen1"));
data.add(new TableData("John2", "A", "Maths", "Hellen2"));
data.add(new TableData("John3", "A", "Maths", "Hellen3"));
data.add(new TableData("John4", "A", "Maths", "Hellen4"));
data.add(new TableData("John5", "A", "Maths", "Hellen5"));
allTableModel = new AllTableModel(data);
}
public void createUI() {
JFrame frame = new JFrame();
tabbedPane = new JTabbedPane();
tabbedPane.add("All", getAllTablePanel());
frame.add(tabbedPane);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setTitle("Table Model Example.");
frame.pack();
frame.setVisible(true);
}
private JPanel getAllTablePanel() {
JPanel panel = new JPanel();
allTable = new JTable(allTableModel);
JScrollPane scroll = new JScrollPane(allTable);
panel.add(scroll);
allTable.addMouseListener(new MouseAdapter() {
#Override
public void mouseReleased(MouseEvent e) {
int r = allTable.rowAtPoint(e.getPoint());
if (r >= 0 && r < allTable.getRowCount()) {
allTable.setRowSelectionInterval(r, r);
} else {
allTable.clearSelection();
}
int rowindex = allTable.getSelectedRow();
if (rowindex < 0)
return;
if (e.getComponent() instanceof JTable) {
JDialog dialog = new JDialog();
int selectedRow = allTable.getSelectedRow();
dialog.setTitle("Edit Row: " + selectedRow);
TableData data = ((AllTableModel) allTable.getModel()).getTableData().get(selectedRow);
List<TableData> tempData = new ArrayList<TableData>();
tempData.add(data);
AllTableModel tempModel = new AllTableModel(tempData);
JTable table = new JTable(tempModel);
dialog.add(new JScrollPane(table));
dialog.setVisible(true);
}
}
});
return panel;
}
public static void main(String[] args) {
Runnable r = new Runnable() {
#Override
public void run() {
new AllTableExample().createUI();
}
};
EventQueue.invokeLater(r);
}
}
class AllTableModel extends AbstractTableModel {
List<TableData> tableData = new ArrayList<TableData>();
Object[] columnNames = {"Name", "Grade", "Subject", "Staff"};
public AllTableModel(List<TableData> data) {
tableData = data;
}
public List<TableData> getTableData() {
return tableData;
}
#Override
public String getColumnName(int column) {
return columnNames[column].toString();
}
#Override
public int getColumnCount() {
return columnNames.length;
}
#Override
public int getRowCount() {
return tableData.size();
}
#Override
public Object getValueAt(int rowIndex, int columnIndex) {
TableData data = tableData.get(rowIndex);
switch (columnIndex) {
case 0:
return data.getName();
case 1:
return data.getGrade();
case 2:
return data.getSubject();
case 3:
return data.getStaff();
default:
return null;
}
}
}
class TableData {
private String name;
private String grade;
private String subject;
private String staff;
public TableData(String name, String grade, String subject, String staff) {
super();
this.name = name;
this.grade = grade;
this.subject = subject;
this.staff = staff;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getGrade() {
return grade;
}
public void setGrade(String grade) {
this.grade = grade;
}
public String getSubject() {
return subject;
}
public void setSubject(String subject) {
this.subject = subject;
}
public String getStaff() {
return staff;
}
public void setStaff(String staff) {
this.staff = staff;
}
}
Note: Store the row number of the table on which the pop-up opened such that after the changes in the popup dialog we have to update the original row.

Edit User information by jtable

I have a jtable that show a text file contain on own.
Each line in text file is a user record.
I add a edit button to edit each selected row on table.
I use this code, But i don't understand how to do this:
public class AllUser extends AbstractTableModel {
UserInformation uiS = new UserInformation();
String[] col = {"ID", "Fname", "Lname", "Gender", "Date"};
List<UserInformation> Udata = new ArrayList<UserInformation>();
public AllUser() {
BufferedReader br = null;
try {
FileReader fr = new FileReader("xxx.txt");
br = new BufferedReader(fr);
String line;
while ((line = br.readLine()) != null) {
if (line.trim().length() == 0) {
continue;
}
Udata.add(initializeUserInfos(line));
}
} catch (IOException e) {
} finally {
if (br != null) {
try {
br.close();
} catch (IOException ioe) {
}
}
}
}
private UserInformation initializeUserInfos(String str) {
UserInformation Uinit = new UserInformation();
String[] CellArray = str.split(" ");
Uinit.setID(CellArray[0]);
Uinit.setFname(CellArray[1]);
Uinit.setLname(CellArray[2]);
Uinit.setGender(CellArray[3]);
Uinit.setDate(CellArray[4]);
return Uinit;
}
#Override
public String getColumnName(int colu) {
return col[colu];
}
#Override
public int getRowCount() {
return Udata.size();
}
#Override
public int getColumnCount() {
return col.length;
}
#Override
public Object getValueAt(int rowIndex, int columnIndex) {
UserInformation uinfoS = Udata.get(rowIndex);
Object value = null;
switch (columnIndex) {
case 0:
value = uinfoS.getID();
break;
case 1:
value = uinfoS.getFname();
break;
case 2:
value = uinfoS.getLname();
break;
case 3:
value = uinfoS.getGender();
break;
case 4:
value = uinfoS.getDate();
break;
default:
value = "...";
}
return value;
}
#Override
public void setValueAt(Object value, int rowIndex, int columnIndex) {
UserInformation userInfo = new UserInformation();
switch (columnIndex) {
case 0:
userInfo.setID((String) value);
break;
case 1:
userInfo.setFname((String) value);
break;
case 2:
userInfo.setLname((String) value);
break;
case 3:
userInfo.setGender((String) value);
break;
case 4:
userInfo.setDate((String) value);
break;
}
}
public Object getSelectedMember(int row){
UserInformation userInf=new UserInformation();
Object fname=userInf.getFname();
Object lname=userInf.getLname();
Object gender=userInf.getGender();
Object date=userInf.getDate();
return // ?
}
}
I add This getSelectedMember(int row) method to do this, But incorrect!
public class UserPage extends JFrame implements ActionListener {
private AllUser userModel;
private JTable uTable;
private JButton editButton;
public UserPage() {
userModel = new AllUser();
uTable = new JTable(userModel);
add(new JScrollPane(uTable), BorderLayout.CENTER);
add(buttonPanels(), BorderLayout.PAGE_START);
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.setSize(800, 600);
}
public final JPanel buttonPanels() {
JPanel buttonsPanel = new JPanel(new FlowLayout(FlowLayout.LEFT));
editButton=new JButton("Edit");
editButton.addActionListener(this);
buttonsPanel.add(editButton);
return buttonsPanel;
}
#Override
public void actionPerformed(ActionEvent e) {
if(e.getSource()== editButton){
int selectedRow=uTable.getSelectedRow();
if(selectedRow>0){
editUser(selectedRow);
}
else{
JOptionPane.showMessageDialog(null, "Select a user");
}
}
}
public void editUser(int row){
userModel.getSelectedMember(row);
new NewUserFrame_Edit().setVisible(true);
}
}
UserInformation Class:
public class UserInformation {
private String Fname;
private String Lname;
private String ID;
private String Gender;
private String Date;
public String getFname() {
return Fname;
}
public void setFname(String fname) {
this.Fname = fname;
}
public String getLname() {
return Lname;
}
public void setLname(String lname) {
this.Lname = lname;
}
public String getID() {
return ID;
}
public void setID(String i_d) {
this.ID = i_d;
}
public String getGender() {
return Gender;
}
public void setGender(String gndr) {
this.Gender = gndr;
}
public String getDate() {
return Date;
}
public void setDate(String date) {
this.Date = date;
}
#Override
public String toString() {
return ID + " " + Fname + " "
+ Lname + " " + Gender + " " + Date + "\n";
}
}
Sorry for long code.

It sould be like this: when user click a row in jtable and clicked a new page should open and then each old data should insert in own textfiled
Add a MouseListener to the table.
On a double click you create a JDialog that contains the text fields required to edit the data.
You then get the data from the table using the getValueAt(...) method.
the user then edits the data in the text fields.
When the user clicks the "Save" button on the dialog you get the data from each text field and update the table using the setValueAt(...) method.
if you want to save the data in your text file you then need to recreate the enitre file by writing out all the data from the table.

Create an extra column in table and fill the cell value with Edit. Then render the Edit cell with appropriate TableCellRenderer . Add MouseListener to table. Get the row and column number of the cell clicked on table. If the cell clicked contains value Edit , retrieve value at each column of that row and display it in a Panel containing JTextFields . Show that Panel using JOptionpane or in a JDialog. Here is the brief code demo for achieving this task:
import java.awt.BorderLayout;
import java.awt.GridLayout;
import java.awt.Component;
import java.awt.Color;
import java.awt.Point;
import java.awt.event.MouseListener;
import java.awt.event.MouseEvent;
import java.awt.event.MouseAdapter;
import java.awt.Cursor;
import javax.swing.BorderFactory;
import javax.swing.border.BevelBorder;
import javax.swing.JFrame;
import javax.swing.JTable;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.JButton;
import javax.swing.JScrollPane;
import javax.swing.JOptionPane;
import javax.swing.JLabel;
import javax.swing.SwingUtilities;
import javax.swing.event.TableModelListener;
import javax.swing.event.TableModelEvent;
import javax.swing.table.TableModel;
import javax.swing.table.AbstractTableModel;
import javax.swing.table.TableColumn;
import javax.swing.table.DefaultTableCellRenderer;
class TableRowEdit extends JFrame
{
private JTable table;
private JScrollPane jsPane;
private TableModel myModel;
private JPanel dialogPanel;
private JTextField tf[];
private JLabel lbl[];
public void prepareAndShowGUI()
{
myModel = new MyModel();
table = new JTable(myModel);
jsPane = new JScrollPane(table);
table.getColumnModel().getColumn(2).setCellRenderer(new LabelCellRenderer());
table.addMouseListener(new MyMouseAdapter());
getContentPane().add(jsPane);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
prepareDialogPanel();
pack();
setVisible(true);
}
private void prepareDialogPanel()
{
dialogPanel = new JPanel();
int col = table.getColumnCount() - 1;
dialogPanel.setLayout(new GridLayout(col,2));
tf = new JTextField[col];
lbl = new JLabel[col];
for (int i = 0; i < col; i++)
{
lbl[i] = new JLabel(table.getColumnName(i));
tf[i] = new JTextField(10);
dialogPanel.add(lbl[i]);
dialogPanel.add(tf[i]);
}
}
private void populateTextField(String[] s)
{
for (int i = 0 ; i < s.length ; i++ )
{
tf[i].setText(s[i]);
}
}
public class LabelCellRenderer extends DefaultTableCellRenderer
{
public Component getTableCellRendererComponent(JTable table,Object oValue, boolean isSelected, boolean hasFocus, int row, int column)
{
Component c = super.getTableCellRendererComponent(table, oValue,isSelected, hasFocus,row, column);
String value = (String)oValue;
JLabel label =(JLabel)c;
label.setBorder(BorderFactory.createBevelBorder(BevelBorder.RAISED));
label.setBackground(Color.lightGray);
label.setHorizontalTextPosition(SwingUtilities.CENTER);
label.setHorizontalAlignment(SwingUtilities.CENTER);
label.setText(value);
return label;
}
}
private class MyMouseAdapter extends MouseAdapter
{
#Override
public void mousePressed(MouseEvent evt)
{
int x = evt.getX();
int y = evt.getY();
int row = table.rowAtPoint(new Point(x,y));
int col = table.columnAtPoint(new Point(x,y));
if (col == 2)
{
String arr[] = new String[table.getColumnCount() - 1];
for (int i = 0 ; i < arr.length ; i++)
{
arr[i] = (String)table.getValueAt(row,i);
}
populateTextField(arr);
JOptionPane.showMessageDialog(TableRowEdit.this,dialogPanel,"Information",JOptionPane.INFORMATION_MESSAGE);
//Write here the code to save changed values to file and update to JTable also.
}
}
}
private class MyModel extends AbstractTableModel
{
String[] columns = {
"Roll No.",
"Name",
"Action"
};
String[][] inData = {
{"1","Huge Jackman","Edit"},
{"2","Thomas Andrews","Edit"},
{"3","Shiney","Edit"}
};
#Override
public void setValueAt(Object value, int row, int col)
{
inData[row][col] = (String)value;
}
#Override
public Object getValueAt(int row, int col)
{
return inData[row][col];
}
#Override
public int getColumnCount()
{
return columns.length;
}
#Override
public int getRowCount()
{
return inData.length;
}
#Override
public String getColumnName(int col)
{
return columns[col];
}
}
public static void main(String st[])
{
SwingUtilities.invokeLater( new Runnable()
{
#Override
public void run()
{
TableRowEdit td = new TableRowEdit();
td.prepareAndShowGUI();
}
});
}
}