插入行选择jTable

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Inserted Row Selection jTable

我有一个 JTable 插入一个空行，当我标记出倒数第二列时，这工作正常。我还添加了 table.setRowSelectionInterval(lastRow,lastRow); 以同时选择我新插入的行，但它抛出了一个 java.lang.NullPointerException

需要帮助才能选择最后插入的行。提前致谢。

public class JFrameTable extends javax.swing.JFrame {



protected JTable table;





public JFrameTable() {

  initComponents();



}



public void setValueAt(int col){

  DefaultTableModel model = (DefaultTableModel) jTable1.getModel();

  if(col==2){

   Vector row = new Vector();

   row.add(null);

   row.add(null);

   row.add(null);

   row.add(null);



  model.addRow(row);

  }

}







private class MyKeyListener implements KeyListener {



  public MyKeyListener() {

  }



  @Override

  public void keyReleased(KeyEvent e) {



    if(e.getKeyCode()==e.VK_TAB){

      int column = jTable1.getSelectedColumn();

      int rowCount= jTable1.getRowCount();

      int currentRow=jTable1.getSelectedRow();

      if(currentRow==rowCount-1) {

        jTable1.editCellAt(currentRow, column);

        jTable1.transferFocus();

     }

     if(column==3 && currentRow==rowCount-1){

        setValueAt(2);

     }

     if(column==3){

       currentRow++;

       column=0;

       jTable1.editCellAt(currentRow, column);

       jTable1.transferFocus();

     try{        

       table.setRowSelectionInterval(rowCount-1,rowCount-1);

     }catch(Exception ek){

       System.out.println(ek);

     } 

     }

     System.out.println(rowCount);

     }



  }

  @Override

  public void keyTyped(KeyEvent e) {



  }

  @Override

  public void keyPressed(KeyEvent e) {



  }



}



private class MySelectionListener implements ListSelectionListener {



  public MySelectionListener() {

  }



  @Override

  public void valueChanged(ListSelectionEvent e) {



  }

}





private class setTableModelListener implements TableModelListener{

  public void tableChanged(TableModelEvent e) {



}

}





@SuppressWarnings("unchecked")

// <editor-fold defaultstate="collapsed" desc="Generated Code">             

private void initComponents() {



  jScrollPane1 = new javax.swing.JScrollPane();

  jTable1 = new javax.swing.JTable();



  setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);



  jTable1.setBackground(new java.awt.Color(75, 107, 221));

  jTable1.setFont(new java.awt.Font("SansSerif", 1, 15)); // NOI18N

  jTable1.setForeground(new java.awt.Color(254, 247, 247));

  jTable1.setModel(new javax.swing.table.DefaultTableModel(

    new Object [][] {

      {null, null, null, null}

    },

    new String [] {

     "Name","Roll","Stream","Sex"

    }

  ) {

    boolean[] canEdit = new boolean [] {

      true, true, true, false

    };



    public boolean isCellEditable(int rowIndex, int columnIndex) {

      return canEdit [columnIndex];

    }

  });

  jTable1.getModel().addTableModelListener(new setTableModelListener());

  jTable1.getTableHeader().setReorderingAllowed(false);

  jTable1.setRowHeight(20);

  jTable1.getTableHeader().setBackground(Color.BLACK);

  jTable1.getTableHeader().setFont(new Font ("SansSerif", Font.BOLD ,15));

  jTable1.getTableHeader().setForeground(Color.WHITE);

  jTable1.getColumnModel().getSelectionModel().addListSelectionListener(new MySelectionListener());

  jTable1.addKeyListener(new MyKeyListener());

  jTable1.setRowSelectionAllowed(true);

  jScrollPane1.setViewportView(jTable1);

  jTable1.getColumnModel().getColumn(0).setResizable(false);

  jTable1.getColumnModel().getColumn(0).setPreferredWidth(150);

  jTable1.getColumnModel().getColumn(1).setResizable(false);

  jTable1.getColumnModel().getColumn(1).setPreferredWidth(50);

  jTable1.getColumnModel().getColumn(2).setResizable(false);

  jTable1.getColumnModel().getColumn(2).setPreferredWidth(30);

  jTable1.getColumnModel().getColumn(3).setResizable(false);



  javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());

  getContentPane().setLayout(layout);

  layout.setHorizontalGroup(

    layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)

    .addComponent(jScrollPane1, javax.swing.GroupLayout.DEFAULT_SIZE, 630, Short.MAX_VALUE)

  );

  layout.setVerticalGroup(

    layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)

    .addGroup(layout.createSequentialGroup()

      .addComponent(jScrollPane1, javax.swing.GroupLayout.PREFERRED_SIZE, 205, javax.swing.GroupLayout.PREFERRED_SIZE)

      .addGap(0, 95, Short.MAX_VALUE))

  );



  pack();

}// </editor-fold>            



/**

* @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(JFrameTable.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);

  } catch (InstantiationException ex) {

    java.util.logging.Logger.getLogger(JFrameTable.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);

  } catch (IllegalAccessException ex) {

    java.util.logging.Logger.getLogger(JFrameTable.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);

  } catch (javax.swing.UnsupportedLookAndFeelException ex) {

    java.util.logging.Logger.getLogger(JFrameTable.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 JFrameTable().setVisible(true);



    }

  });

}

// Variables declaration - do not modify           

private javax.swing.JScrollPane jScrollPane1;

private javax.swing.JTable jTable1;

// End of variables declaration          

 }

import java.awt.EventQueue;

import java.awt.event.ActionEvent;

import java.awt.event.KeyEvent;

import java.util.Vector;

import javax.swing.AbstractAction;

import javax.swing.ActionMap;

import javax.swing.InputMap;

import javax.swing.JFrame;

import javax.swing.JScrollPane;

import javax.swing.JTable;

import javax.swing.KeyStroke;

import javax.swing.UIManager;

import javax.swing.UnsupportedLookAndFeelException;

import javax.swing.table.DefaultTableModel;



public class TestTable {



  public static void main(String[] args) {

    new TestTable();

  }



  public TestTable() {

    EventQueue.invokeLater(new Runnable() {

      @Override

      public void run() {

        try {

          UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());

        } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {

          ex.printStackTrace();

        }



        DefaultTableModel model = new DefaultTableModel(4, 4);

        JTable table = new JTable(model);



        InputMap im = table.getInputMap();

        im.put(KeyStroke.getKeyStroke(KeyEvent.VK_TAB, 0),"CellAction");



        ActionMap am = table.getActionMap();

        am.put("CellAction", new CellAction(table));



        JFrame frame = new JFrame("Testing");

        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        frame.add(new JScrollPane(table));

        frame.pack();

        frame.setLocationRelativeTo(null);

        frame.setVisible(true);

      }

    });

  }



  public class CellAction extends AbstractAction {



    private JTable table;



    public CellAction(JTable table) {

      this.table = table;

    }



    @Override

    public void actionPerformed(ActionEvent e) {

      int column = table.getSelectedColumn();

      int rowCount = table.getRowCount();

      int currentRow = table.getSelectedRow();

      if (currentRow == rowCount - 1) {

        table.editCellAt(currentRow, column);

      }

      if (column == 3 && currentRow == rowCount - 1) {

        DefaultTableModel model = (DefaultTableModel) table.getModel();

        Vector row = new Vector();

        row.add(null);

        row.add(null);

        row.add(null);

        row.add(null);



        model.addRow(row);

      }

      if (column == 3) {

        currentRow++;

        column = 0;

        table.setRowSelectionInterval(currentRow, currentRow);

        table.setColumnSelectionInterval(column, column);

        table.editCellAt(currentRow, column);

      }

    }



  }



}

有几件事不对...

  • 避免使用 KeyListener，使用键绑定 API 修复了与使用 KeyListener 相关的大量问题
  • 您使用 table.setRowSelectionInterval(rowCount-1,rowCount-1); 选择行，但 rowCount 不再有效，因为您已添加新行
  • transferFocus 用于将焦点转移到下一个可聚焦组件，这意味着 JTable 很可能会失去焦点，很确定这不是您想要的。

    • 例如...

    public class JFrameTable extends javax.swing.JFrame {



protected JTable table;





public JFrameTable() {

  initComponents();



}



public void setValueAt(int col){

  DefaultTableModel model = (DefaultTableModel) jTable1.getModel();

  if(col==2){

   Vector row = new Vector();

   row.add(null);

   row.add(null);

   row.add(null);

   row.add(null);



  model.addRow(row);

  }

}







private class MyKeyListener implements KeyListener {



  public MyKeyListener() {

  }



  @Override

  public void keyReleased(KeyEvent e) {



    if(e.getKeyCode()==e.VK_TAB){

      int column = jTable1.getSelectedColumn();

      int rowCount= jTable1.getRowCount();

      int currentRow=jTable1.getSelectedRow();

      if(currentRow==rowCount-1) {

        jTable1.editCellAt(currentRow, column);

        jTable1.transferFocus();

     }

     if(column==3 && currentRow==rowCount-1){

        setValueAt(2);

     }

     if(column==3){

       currentRow++;

       column=0;

       jTable1.editCellAt(currentRow, column);

       jTable1.transferFocus();

     try{        

       table.setRowSelectionInterval(rowCount-1,rowCount-1);

     }catch(Exception ek){

       System.out.println(ek);

     } 

     }

     System.out.println(rowCount);

     }



  }

  @Override

  public void keyTyped(KeyEvent e) {



  }

  @Override

  public void keyPressed(KeyEvent e) {



  }



}



private class MySelectionListener implements ListSelectionListener {



  public MySelectionListener() {

  }



  @Override

  public void valueChanged(ListSelectionEvent e) {



  }

}





private class setTableModelListener implements TableModelListener{

  public void tableChanged(TableModelEvent e) {



}

}





@SuppressWarnings("unchecked")

// <editor-fold defaultstate="collapsed" desc="Generated Code">             

private void initComponents() {



  jScrollPane1 = new javax.swing.JScrollPane();

  jTable1 = new javax.swing.JTable();



  setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);



  jTable1.setBackground(new java.awt.Color(75, 107, 221));

  jTable1.setFont(new java.awt.Font("SansSerif", 1, 15)); // NOI18N

  jTable1.setForeground(new java.awt.Color(254, 247, 247));

  jTable1.setModel(new javax.swing.table.DefaultTableModel(

    new Object [][] {

      {null, null, null, null}

    },

    new String [] {

     "Name","Roll","Stream","Sex"

    }

  ) {

    boolean[] canEdit = new boolean [] {

      true, true, true, false

    };



    public boolean isCellEditable(int rowIndex, int columnIndex) {

      return canEdit [columnIndex];

    }

  });

  jTable1.getModel().addTableModelListener(new setTableModelListener());

  jTable1.getTableHeader().setReorderingAllowed(false);

  jTable1.setRowHeight(20);

  jTable1.getTableHeader().setBackground(Color.BLACK);

  jTable1.getTableHeader().setFont(new Font ("SansSerif", Font.BOLD ,15));

  jTable1.getTableHeader().setForeground(Color.WHITE);

  jTable1.getColumnModel().getSelectionModel().addListSelectionListener(new MySelectionListener());

  jTable1.addKeyListener(new MyKeyListener());

  jTable1.setRowSelectionAllowed(true);

  jScrollPane1.setViewportView(jTable1);

  jTable1.getColumnModel().getColumn(0).setResizable(false);

  jTable1.getColumnModel().getColumn(0).setPreferredWidth(150);

  jTable1.getColumnModel().getColumn(1).setResizable(false);

  jTable1.getColumnModel().getColumn(1).setPreferredWidth(50);

  jTable1.getColumnModel().getColumn(2).setResizable(false);

  jTable1.getColumnModel().getColumn(2).setPreferredWidth(30);

  jTable1.getColumnModel().getColumn(3).setResizable(false);



  javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());

  getContentPane().setLayout(layout);

  layout.setHorizontalGroup(

    layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)

    .addComponent(jScrollPane1, javax.swing.GroupLayout.DEFAULT_SIZE, 630, Short.MAX_VALUE)

  );

  layout.setVerticalGroup(

    layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)

    .addGroup(layout.createSequentialGroup()

      .addComponent(jScrollPane1, javax.swing.GroupLayout.PREFERRED_SIZE, 205, javax.swing.GroupLayout.PREFERRED_SIZE)

      .addGap(0, 95, Short.MAX_VALUE))

  );



  pack();

}// </editor-fold>            



/**

* @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(JFrameTable.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);

  } catch (InstantiationException ex) {

    java.util.logging.Logger.getLogger(JFrameTable.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);

  } catch (IllegalAccessException ex) {

    java.util.logging.Logger.getLogger(JFrameTable.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);

  } catch (javax.swing.UnsupportedLookAndFeelException ex) {

    java.util.logging.Logger.getLogger(JFrameTable.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 JFrameTable().setVisible(true);



    }

  });

}

// Variables declaration - do not modify           

private javax.swing.JScrollPane jScrollPane1;

private javax.swing.JTable jTable1;

// End of variables declaration          

 }

import java.awt.EventQueue;

import java.awt.event.ActionEvent;

import java.awt.event.KeyEvent;

import java.util.Vector;

import javax.swing.AbstractAction;

import javax.swing.ActionMap;

import javax.swing.InputMap;

import javax.swing.JFrame;

import javax.swing.JScrollPane;

import javax.swing.JTable;

import javax.swing.KeyStroke;

import javax.swing.UIManager;

import javax.swing.UnsupportedLookAndFeelException;

import javax.swing.table.DefaultTableModel;



public class TestTable {



  public static void main(String[] args) {

    new TestTable();

  }



  public TestTable() {

    EventQueue.invokeLater(new Runnable() {

      @Override

      public void run() {

        try {

          UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());

        } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {

          ex.printStackTrace();

        }



        DefaultTableModel model = new DefaultTableModel(4, 4);

        JTable table = new JTable(model);



        InputMap im = table.getInputMap();

        im.put(KeyStroke.getKeyStroke(KeyEvent.VK_TAB, 0),"CellAction");



        ActionMap am = table.getActionMap();

        am.put("CellAction", new CellAction(table));



        JFrame frame = new JFrame("Testing");

        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        frame.add(new JScrollPane(table));

        frame.pack();

        frame.setLocationRelativeTo(null);

        frame.setVisible(true);

      }

    });

  }



  public class CellAction extends AbstractAction {



    private JTable table;



    public CellAction(JTable table) {

      this.table = table;

    }



    @Override

    public void actionPerformed(ActionEvent e) {

      int column = table.getSelectedColumn();

      int rowCount = table.getRowCount();

      int currentRow = table.getSelectedRow();

      if (currentRow == rowCount - 1) {

        table.editCellAt(currentRow, column);

      }

      if (column == 3 && currentRow == rowCount - 1) {

        DefaultTableModel model = (DefaultTableModel) table.getModel();

        Vector row = new Vector();

        row.add(null);

        row.add(null);

        row.add(null);

        row.add(null);



        model.addRow(row);

      }

      if (column == 3) {

        currentRow++;

        column = 0;

        table.setRowSelectionInterval(currentRow, currentRow);

        table.setColumnSelectionInterval(column, column);

        table.editCellAt(currentRow, column);

      }

    }



  }



}

    似乎拼写错误，只需更改

    table.setRowSelectionInterval(rowCount-1,rowCount-1); 到

    jTable1.setRowSelectionInterval(rowCount-1,rowCount-1);。

    因为 table 为空。在你使用 jTable1.

    的任何地方

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