Dereferenzierung mögliche Nullzeiger Ausnahme in einer if-Anweisung mit JdateChioser

Question

Ich bin ein Anfänger in der Programmierung, also wenn möglich helfen Sie mir aus! Ich mache ein Programm, das zu DataBase (MySQL) auswählt, abhängig davon, nach welcher Benutzerauswahl gesucht wird. Programm hat 4 verschiedene Dinge zu suchen: Artigo, Cliente, Vendedor und Daten, die 2 jDateChoosers (es wird zwischen ersten und zweiten Datum abfragen). Also ich brauche 16 wenn Bedingungen um alle möglichen Kombinationen zu fangen.

Hier ist mein Code über ein Ereignis, die jTextFieldClienteKeyReleased, berücksichtigen, dass der Code in allen anderen TextFieldsKeyReleased und jDateChoosersMouseClicked gleich ist.

 private void jTextFieldPorVendedorKeyReleased(java.awt.event.KeyEvent evt) { 
// TODO add your handling code here 
    // Se artigo, cliente, vendedor e data forem pesquisados fazer a seguinte consulta SQL 

     SimpleDateFormat sd1 = new SimpleDateFormat("yyyy-MM-dd"); 
     String DataInicial1 = sd1.format(jDateChooserInicial.getDate()); 

     SimpleDateFormat sd2 = new SimpleDateFormat("yyyy-MM-dd"); 
     String DataFinal1 = sd2.format(jDateChooserFinal.getDate()); 

    if(!(jTextFieldPorArtigo.getText().isEmpty()) && (!(jTextFieldPorCliente.getText().isEmpty())) && (!(jTextFieldPorVendedor.getText().isEmpty())) && (!(jDateChooserInicial.getDate().toString().isEmpty())) && (!(jDateChooserFinal.getDate().toString().isEmpty()))) { 
     try { 

       PreparedStatement preparedStatement; //1 SELECT * FROM fatura WHERE CodArt LIKE '%AES%' AND CodCli = 1 AND CodVendedor = 1 AND Data >= '2015/03/25' AND Data <= '2017/02/27' 
       preparedStatement = ligacao.prepareStatement("SELECT * FROM fatura WHERE CodArt LIKE '%" 
         + jTextFieldPorArtigo.getText() 
         + "%' AND " 
         + " CodCli = " 
         + jTextFieldPorCliente.getText() 
         + " AND " 
         + "CodVendedor = " 
         + jTextFieldPorVendedor.getText() 
         + " AND " 
         + "Data >= '" 
         + DataInicial1 
         + "' AND " 
         + " Data <= '" 
         + DataFinal1 
         + "'"); 
       System.out.println(preparedStatement);         
       ResultSet resultSetForFullTable = preparedStatement.executeQuery(); 
       jTableVendas.setModel(DbUtils.resultSetToTableModel(resultSetForFullTable)); 

      } catch (SQLException ex) { 
       System.out.println(ex); 
             } 
     //Se artigo, cliente e vendedor estiverem a ser pesquisados fazer a seguinte consulta SQL 
} 
     SimpleDateFormat sd3 = new SimpleDateFormat("yyyy-MM-dd"); 
     String DataInicial2 = sd3.format(jDateChooserInicial.getDate()); 

     SimpleDateFormat sd4 = new SimpleDateFormat("yyyy-MM-dd"); 
     String DataFinal2 = sd4.format(jDateChooserFinal.getDate()); 

     if(!(jTextFieldPorArtigo.getText().isEmpty()) && (!(jTextFieldPorCliente.getText().isEmpty())) && (!(jTextFieldPorVendedor.getText().isEmpty())) && (jDateChooserInicial.getDate().toString().isEmpty()) && (jDateChooserFinal.getDate().toString().isEmpty()) || ((DataInicial2 == null)) || ((DataFinal2 == null))) /*|| (jDateChooserInicial.getDateFormatString().contains("yyyy-MM-dd")) || (jDateChooserFinal.getDateFormatString().contains("yyyy-MM-dd")))*/ { 
     try { 
       PreparedStatement preparedStatement; //2 SELECT * FROM fatura WHERE CodArt LIKE '%39%' AND CodCli = 1 AND CodVendedor = 1 
       preparedStatement = ligacao.prepareStatement("SELECT * FROM fatura WHERE CodArt LIKE '%" 
         + jTextFieldPorArtigo.getText() 
         + "%' AND " 
         + "CodCli = " 
         + jTextFieldPorCliente.getText() 
         + " AND " 
         + "CodVendedor = " 
         + jTextFieldPorVendedor.getText() 
         + ""); 

       System.out.println(preparedStatement); 
       ResultSet resultSetForFullTable = preparedStatement.executeQuery(); 
       jTableVendas.setModel(DbUtils.resultSetToTableModel(resultSetForFullTable)); 

      } catch (SQLException ex) { 
       System.out.println(ex); 
             } 

      // Se artigo, cliente e data estiverem a ser pesquisados fazer a seguinte consulta SQL 
} 
     SimpleDateFormat sd5 = new SimpleDateFormat("yyyy-MM-dd"); 
     String DataInicial3 = sd5.format(jDateChooserInicial.getDate()); 

     SimpleDateFormat sd6 = new SimpleDateFormat("yyyy-MM-dd"); 
     String DataFinal3 = sd6.format(jDateChooserFinal.getDate()); 

      if(!(jTextFieldPorArtigo.getText().isEmpty()) && (!(jTextFieldPorCliente.getText().isEmpty())) && ((jTextFieldPorVendedor.getText().isEmpty())) && (!(jDateChooserInicial.getDate().toString().isEmpty())) && (!(jDateChooserFinal.getDate().toString().isEmpty()))) { 
      try { 

       PreparedStatement preparedStatement; //3 SELECT * FROM fatura WHERE CodArt = 2 AND CodCli = 1 AND Data >= '2015/03/25' AND Data <= '2017/02/27' 
       preparedStatement = ligacao.prepareStatement("SELECT * FROM fatura WHERE CodArt LIKE '%" 
         + jTextFieldPorArtigo.getText() 
         + "%' AND " 
         + " CodCli = " 
         + jTextFieldPorCliente.getText() 
         + " AND " 
         + " Data >= '" 
         + DataInicial3 
         + "' AND " 
         + " Data <= '" 
         + DataFinal3 
         + "'"); 
       System.out.println(preparedStatement);            
       ResultSet resultSetForFullTable = preparedStatement.executeQuery(); 
       jTableVendas.setModel(DbUtils.resultSetToTableModel(resultSetForFullTable)); 

      } catch (SQLException ex) { 
       System.out.println(ex); 
             } 

     // Se artigo e cliente estiverem a ser pesquisados fazer a seguinte consulta SQL 
} 
     SimpleDateFormat sd7 = new SimpleDateFormat("yyyy-MM-dd"); 
     String DataInicial4 = sd7.format(jDateChooserInicial.getDate()); 

     SimpleDateFormat sd8 = new SimpleDateFormat("yyyy-MM-dd"); 
     String DataFinal4 = sd8.format(jDateChooserFinal.getDate()); 

      if(!(jTextFieldPorArtigo.getText().isEmpty()) && (!(jTextFieldPorCliente.getText().isEmpty())) && ((jTextFieldPorVendedor.getText().isEmpty())) && (jDateChooserInicial.getDate().toString().isEmpty()) && (jDateChooserFinal.getDate().toString().isEmpty()) || ((DataInicial4 == null)) || ((DataFinal4 == null))) { 
      try { 
       PreparedStatement preparedStatement; //4 SELECT * FROM fatura WHERE CodArt = 1 AND CodCli = 1 
       preparedStatement = ligacao.prepareStatement("SELECT * FROM fatura WHERE CodArt LIKE '%" 
         + jTextFieldPorArtigo.getText() 
         + "%' AND " 
         + " CodCli = " 
         + jTextFieldPorCliente.getText() 
         + ""); 
       System.out.println(preparedStatement); 
       ResultSet resultSetForFullTable = preparedStatement.executeQuery(); 
       jTableVendas.setModel(DbUtils.resultSetToTableModel(resultSetForFullTable)); 

      } catch (SQLException ex) { 
       System.out.println(ex); 
             } 

     // Se artigo, vendedor e data estiverem a ser pesquisados fazer a seguinte consulta SQL 
}   
     SimpleDateFormat sd9 = new SimpleDateFormat("yyyy-MM-dd"); 
     String DataInicial5 = sd9.format(jDateChooserInicial.getDate()); 

     SimpleDateFormat sd10 = new SimpleDateFormat("yyyy-MM-dd"); 
     String DataFinal5 = sd10.format(jDateChooserFinal.getDate()); 

      if(!(jTextFieldPorArtigo.getText().isEmpty()) && ((jTextFieldPorCliente.getText().isEmpty())) && (!(jTextFieldPorVendedor.getText().isEmpty())) && (!(jDateChooserInicial.getDate().toString().isEmpty())) && (!(jDateChooserFinal.getDate().toString().isEmpty()))) { 
     try { 

       PreparedStatement preparedStatement; //5 SELECT * FROM fatura WHERE CodArt = 2 AND CodVendedor = 1 AND Data >= '2015/03/25' AND Data <= '2017/02/27' 
       preparedStatement = ligacao.prepareStatement("SELECT * FROM fatura WHERE CodArt LIKE '%" 
         + jTextFieldPorArtigo.getText() 
         + "%' AND " 
         + " CodVendedor = " 
         + jTextFieldPorVendedor.getText() 
         + " AND " 
         + " Data >= '" 
         + DataInicial5 
         + "' AND " 
         + " Data <= '" 
         + DataFinal5 
         + "'"); 
       System.out.println(preparedStatement);         
       ResultSet resultSetForFullTable = preparedStatement.executeQuery(); 
       jTableVendas.setModel(DbUtils.resultSetToTableModel(resultSetForFullTable)); 

      } catch (SQLException ex) { 
       System.out.println(ex); 
             } 

     // Se artigo e vendedor estiverem a ser pesquisados fazer a seguinte consulta SQL 
} 
     SimpleDateFormat sd11 = new SimpleDateFormat("yyyy-MM-dd"); 
     String DataInicial6 = sd11.format(jDateChooserInicial.getDate()); 

     SimpleDateFormat sd12 = new SimpleDateFormat("yyyy-MM-dd"); 
     String DataFinal6 = sd12.format(jDateChooserFinal.getDate()); 

      if(!(jTextFieldPorArtigo.getText().isEmpty()) && ((jTextFieldPorCliente.getText().isEmpty())) && (!(jTextFieldPorVendedor.getText().isEmpty())) && (jDateChooserInicial.getDate().toString().isEmpty()) && (jDateChooserFinal.getDate().toString().isEmpty()) || ((DataInicial6 == null)) || ((DataFinal6 == null))){ 
      try { 
       PreparedStatement preparedStatement; //6 SELECT * FROM fatura WHERE CodArt = 1 AND CodVendedor = 2 
       preparedStatement = ligacao.prepareStatement("SELECT * FROM fatura WHERE CodArt LIKE '%" 
         + jTextFieldPorArtigo.getText() 
         + "%' AND " 
         + " CodVendedor = " 
         + jTextFieldPorVendedor.getText() 
         + ""); 
       System.out.println(preparedStatement);         
       ResultSet resultSetForFullTable = preparedStatement.executeQuery(); 
       jTableVendas.setModel(DbUtils.resultSetToTableModel(resultSetForFullTable)); 

      } catch (SQLException ex) {  
       System.out.println(ex); 
             } 

     // Se artigo e data estiverem a ser pesquisados fazer a seguinte consulta SQL 
} 
     SimpleDateFormat sd13 = new SimpleDateFormat("yyyy-MM-dd"); 
     String DataInicial7 = sd13.format(jDateChooserInicial.getDate()); 

     SimpleDateFormat sd14 = new SimpleDateFormat("yyyy-MM-dd"); 
     String DataFinal7 = sd14.format(jDateChooserFinal.getDate()); 

     if(!(jTextFieldPorArtigo.getText().isEmpty()) && ((jTextFieldPorCliente.getText().isEmpty())) && ((jTextFieldPorVendedor.getText().isEmpty())) && (!(jDateChooserInicial.getDate().toString().isEmpty())) && (!(jDateChooserFinal.getDate().toString().isEmpty()))){ 
     try { 

       PreparedStatement preparedStatement; //7 SELECT * FROM fatura WHERE CodArt = 2 AND Data >= '2015/03/25' AND Data <= '2017/02/27' 
       preparedStatement = ligacao.prepareStatement("SELECT * FROM fatura WHERE CodArt LIKE '%" 
         + jTextFieldPorArtigo.getText() 
         + "%' AND " 
         + " Data >= '" 
         + DataInicial7 
         + "' AND " 
         + " Data <= '" 
         + DataFinal7 
         + "'"); 
       System.out.println(preparedStatement);         
       ResultSet resultSetForFullTable = preparedStatement.executeQuery(); 
       jTableVendas.setModel(DbUtils.resultSetToTableModel(resultSetForFullTable)); 

      } catch (SQLException ex) { 
       System.out.println(ex); 
             } 

     // Se apenas artigo estiver a ser pesquisado fazer a seguinte consulta SQL 
} 
     SimpleDateFormat sd15 = new SimpleDateFormat("yyyy-MM-dd"); 
     String DataInicial8 = sd15.format(jDateChooserInicial.getDate()); 

     SimpleDateFormat sd16 = new SimpleDateFormat("yyyy-MM-dd"); 
     String DataFinal8 = sd16.format(jDateChooserFinal.getDate()); 

     if(!(jTextFieldPorArtigo.getText().isEmpty()) && ((jTextFieldPorCliente.getText().isEmpty())) && ((jTextFieldPorVendedor.getText().isEmpty())) && (jDateChooserInicial.getDate().toString().isEmpty()) && (jDateChooserFinal.getDate().toString().isEmpty()) || ((DataInicial8 == null)) || ((DataFinal8 == null))){ 
     try { 
       PreparedStatement preparedStatement; //8 SELECT * FROM `fatura` WHERE CodArt LIKE '%AM%' 
       preparedStatement = ligacao.prepareStatement("SELECT * FROM fatura WHERE CodArt LIKE '%" 
         + jTextFieldPorArtigo.getText() 
         + "%'"); 
       System.out.println(preparedStatement);         
       ResultSet resultSetForFullTable = preparedStatement.executeQuery(); 
       jTableVendas.setModel(DbUtils.resultSetToTableModel(resultSetForFullTable)); 

      } catch (SQLException ex) { 
       System.out.println(ex); 
             } 

Answer 1

(Dies ist der des Codes weiter, ich nicht den ganzen Code in derselben Frage stellen könnte, hat es eine Grenze von Zeichen)

// Se cliente, vendedor e data estiverem a ser pesquisados fazer a seguinte consulta SQL 
} if((jTextFieldPorArtigo.getText().isEmpty()) && (!(jTextFieldPorCliente.getText().isEmpty())) && (!(jTextFieldPorVendedor.getText().isEmpty())) && (!(jDateChooserInicial.getDate().toString().isEmpty())) && (!(jDateChooserFinal.getDate().toString().isEmpty()))) { 
     try { 

     SimpleDateFormat sd17 = new SimpleDateFormat("yyyy-MM-dd"); 
     String DataInicial9 = sd17.format(jDateChooserInicial.getDate()); 

     SimpleDateFormat sd18 = new SimpleDateFormat("yyyy-MM-dd"); 
     String DataFinal9 = sd18.format(jDateChooserFinal.getDate()); 

       PreparedStatement preparedStatement; //9 SELECT * FROM fatura WHERE CodCli = 1 AND CodVendedor = 2 Data >= '2015/03/25' AND Data <= '2017/02/27' 
       preparedStatement = ligacao.prepareStatement("SELECT * FROM fatura WHERE CodCli =" 
         + jTextFieldPorCliente.getText() 
         + " AND " 
         + " CodVendedor = " 
         + jTextFieldPorVendedor.getText() 
         + " AND " 
         + " Data >= '" 
         + DataInicial9 
         + "' AND " 
         + " Data <= '" 
         + DataFinal9 
         + "'"); 
       System.out.println(preparedStatement); 
       ResultSet resultSetForFullTable = preparedStatement.executeQuery(); 
       jTableVendas.setModel(DbUtils.resultSetToTableModel(resultSetForFullTable)); 

      } catch (SQLException ex) { 
       System.out.println(ex); 
             } 

     // Se cliente e vendedor estiverem a ser pesquisados fazer a seguinte consulta SQL 
} 
     SimpleDateFormat sd19 = new SimpleDateFormat("yyyy-MM-dd"); 
     String DataInicial10 = sd19.format(jDateChooserInicial.getDate()); 

     SimpleDateFormat sd20 = new SimpleDateFormat("yyyy-MM-dd"); 
     String DataFinal10 = sd20.format(jDateChooserFinal.getDate()); 

     if((jTextFieldPorArtigo.getText().isEmpty()) && (!(jTextFieldPorCliente.getText().isEmpty())) && (!(jTextFieldPorVendedor.getText().isEmpty())) && (jDateChooserInicial.getDate().toString().isEmpty()) && (jDateChooserFinal.getDate().toString().isEmpty()) || ((DataInicial10 == null)) || ((DataFinal10 == null))) { 
     try { 
       PreparedStatement preparedStatement; //10 SELECT * FROM fatura WHERE CodCli = 1 AND CodVendedor = 2 
       preparedStatement = ligacao.prepareStatement("SELECT * FROM fatura WHERE CodCli =" 
         + jTextFieldPorCliente.getText() 
         + " AND " 
         + " CodVendedor = " 
         + jTextFieldPorVendedor.getText() 
         + ""); 
       System.out.println(preparedStatement); 
       ResultSet resultSetForFullTable = preparedStatement.executeQuery(); 
       jTableVendas.setModel(DbUtils.resultSetToTableModel(resultSetForFullTable)); 

      } catch (SQLException ex) { 
       System.out.println(ex); 
             } 

     // Se cliente e data estiverem a ser pesquisados fazer a seguinte consulta SQL 
} 
     SimpleDateFormat sd21 = new SimpleDateFormat("yyyy-MM-dd"); 
     String DataInicial11 = sd21.format(jDateChooserInicial.getDate()); 

     SimpleDateFormat sd22 = new SimpleDateFormat("yyyy-MM-dd"); 
     String DataFinal11 = sd22.format(jDateChooserFinal.getDate()); 

     if((jTextFieldPorArtigo.getText().isEmpty()) && (!(jTextFieldPorCliente.getText().isEmpty())) && ((jTextFieldPorVendedor.getText().isEmpty())) && (!(jDateChooserInicial.getDate().toString().isEmpty())) && (!(jDateChooserFinal.getDate().toString().isEmpty()))) { 
     try { 

       PreparedStatement preparedStatement; //11 SELECT * FROM fatura WHERE CodCli = 1 AND Data >= '2015/03/25' AND Data <= '2017/02/27' 
       preparedStatement = ligacao.prepareStatement("SELECT * FROM fatura WHERE CodCli =" 
         + jTextFieldPorCliente.getText() 
         + " AND " 
         + " Data >= '" 
         + DataInicial11 
         + "' AND " 
         + " Data <= '" 
         + DataFinal11 
         + "'"); 
       System.out.println(preparedStatement); 
       ResultSet resultSetForFullTable = preparedStatement.executeQuery(); 
       jTableVendas.setModel(DbUtils.resultSetToTableModel(resultSetForFullTable)); 

      } catch (SQLException ex) { 
       System.out.println(ex); 
             } 

     // Se apenas cliente estiver a ser pesquisado fazer a seguinte consulta SQL 
} 
     SimpleDateFormat sd23 = new SimpleDateFormat("yyyy-MM-dd"); 
     String DataInicial12 = sd23.format(jDateChooserInicial.getDate()); 

     SimpleDateFormat sd24 = new SimpleDateFormat("yyyy-MM-dd"); 
     String DataFinal12 = sd24.format(jDateChooserFinal.getDate()); 

     if((jTextFieldPorArtigo.getText().isEmpty()) && (!(jTextFieldPorCliente.getText().isEmpty())) && ((jTextFieldPorVendedor.getText().isEmpty())) && (jDateChooserInicial.getDate().toString().isEmpty()) && (jDateChooserFinal.getDate().toString().isEmpty()) || ((DataInicial12 == null)) || ((DataFinal12 == null))) { 
     try { 
       PreparedStatement preparedStatement; //12 SELECT * FROM fatura WHERE CodCli = 1 
       preparedStatement = ligacao.prepareStatement("SELECT * FROM fatura WHERE CodCli = " 
         + jTextFieldPorCliente.getText() 
         + "");     
       System.out.println(preparedStatement); 
       ResultSet resultSetForFullTable = preparedStatement.executeQuery(); 
       jTableVendas.setModel(DbUtils.resultSetToTableModel(resultSetForFullTable)); 

      } catch (SQLException ex) { 
       System.out.println(ex); 
             } 

     // Se vendedor e data estiverem a ser pesquisados fazer a seguinte consulta SQL 
} 
     SimpleDateFormat sd25 = new SimpleDateFormat("yyyy-MM-dd"); 
     String DataInicial13 = sd25.format(jDateChooserInicial.getDate()); 

     SimpleDateFormat sd26 = new SimpleDateFormat("yyyy-MM-dd"); 
     String DataFinal13 = sd26.format(jDateChooserFinal.getDate()); 

     if((jTextFieldPorArtigo.getText().isEmpty()) && ((jTextFieldPorCliente.getText().isEmpty())) && (!(jTextFieldPorVendedor.getText().isEmpty())) && (!(jDateChooserInicial.getDate().toString().isEmpty())) && (!(jDateChooserFinal.getDate().toString().isEmpty()))) { 
     try { 

       PreparedStatement preparedStatement; //13 SELECT * FROM fatura WHERE CodVendedor = 2 AND Data >= '2015/03/25' AND Data <= '2017/02/27' 
       preparedStatement = ligacao.prepareStatement("SELECT * FROM fatura WHERE CodVendedor =" 
         + jTextFieldPorVendedor.getText() 
         + " AND " 
         + " Data >= '" 
         + DataInicial13 
         + "' AND " 
         + " Data <= '" 
         + DataFinal13 
         + "'"); 
       System.out.println(preparedStatement); 
       ResultSet resultSetForFullTable = preparedStatement.executeQuery(); 
       jTableVendas.setModel(DbUtils.resultSetToTableModel(resultSetForFullTable)); 

      } catch (SQLException ex) { 
       System.out.println(ex); 
             } 

     // Se apenas vendedor estiver a ser pesquisado fazer a seguinte consulta SQL 
} 
     SimpleDateFormat sd27 = new SimpleDateFormat("yyyy-MM-dd"); 
     String DataInicial14 = sd27.format(jDateChooserInicial.getDate()); 

     SimpleDateFormat sd28 = new SimpleDateFormat("yyyy-MM-dd"); 
     String DataFinal14 = sd28.format(jDateChooserFinal.getDate()); 

     if((jTextFieldPorArtigo.getText().isEmpty()) && ((jTextFieldPorCliente.getText().isEmpty())) && (!(jTextFieldPorVendedor.getText().isEmpty())) && (jDateChooserInicial.getDate().toString().isEmpty()) && (jDateChooserFinal.getDate().toString().isEmpty()) || ((DataInicial14 == null)) || ((DataFinal14 == null))) { 
     try { 
       PreparedStatement preparedStatement; //14 SELECT * FROM fatura WHERE CodVendedor = 2 
       preparedStatement = ligacao.prepareStatement("SELECT * FROM fatura WHERE CodVendedor =" 
         + jTextFieldPorVendedor.getText() 
         + "");      
       System.out.println(preparedStatement); 
       ResultSet resultSetForFullTable = preparedStatement.executeQuery(); 
       jTableVendas.setModel(DbUtils.resultSetToTableModel(resultSetForFullTable)); 

      } catch (SQLException ex) { 
       System.out.println(ex); 
             } 

     // Se apenas data estiver a ser pesquisada fazer a seguinte consulta SQL 
} 
     SimpleDateFormat sd29 = new SimpleDateFormat("yyyy-MM-dd"); 
     String DataInicial15 = sd29.format(jDateChooserInicial.getDate()); 

     SimpleDateFormat sd30 = new SimpleDateFormat("yyyy-MM-dd"); 
     String DataFinal15 = sd30.format(jDateChooserFinal.getDate()); 

     if((jTextFieldPorArtigo.getText().isEmpty()) && ((jTextFieldPorCliente.getText().isEmpty())) && ((jTextFieldPorVendedor.getText().isEmpty())) && (!(jDateChooserInicial.getDate().toString().isEmpty())) && (!(jDateChooserFinal.getDate().toString().isEmpty()))) { 
     try { 

       PreparedStatement preparedStatement; //15 SELECT * FROM fatura WHERE Data >= '2015/03/25' AND Data <= '2017/02/27' 
       preparedStatement = ligacao.prepareStatement("SELECT * FROM fatura WHERE Data >= '" 
         + DataInicial15 
         + "' AND " 
         + " Data <= '" 
         + DataFinal15 
         + "'"); 
       System.out.println(preparedStatement); 
       ResultSet resultSetForFullTable = preparedStatement.executeQuery(); 
       jTableVendas.setModel(DbUtils.resultSetToTableModel(resultSetForFullTable)); 

      } catch (SQLException ex) { 
       System.out.println(ex); 
             } 

    // Se nenhum campo estiver a ser pesquisado fazer a seguinte consulta SQL 
} 
     SimpleDateFormat sd31 = new SimpleDateFormat("yyyy-MM-dd"); 
     String DataInicial16 = sd31.format(jDateChooserInicial.getDate()); 

     SimpleDateFormat sd32 = new SimpleDateFormat("yyyy-MM-dd"); 
     String DataFinal16 = sd32.format(jDateChooserFinal.getDate()); 

     if((jTextFieldPorArtigo.getText().isEmpty()) && ((jTextFieldPorCliente.getText().isEmpty())) && ((jTextFieldPorVendedor.getText().isEmpty())) && (jDateChooserInicial.getDate().toString().isEmpty()) && (jDateChooserFinal.getDate().toString().isEmpty()) || ((DataInicial16 == null)) || ((DataFinal16 == null))) { 
     try { 
       PreparedStatement preparedStatement; //16 SELECT * FROM fatura 
       preparedStatement = ligacao.prepareStatement("SELECT * FROM fatura");      
       System.out.println(preparedStatement); 
       ResultSet resultSetForFullTable = preparedStatement.executeQuery(); 
       jTableVendas.setModel(DbUtils.resultSetToTableModel(resultSetForFullTable)); 

      } catch (SQLException ex) { 
       System.out.println(ex); 
             } 
} 

Wenn der Benutzer searchs mit allem, was hat Zur gleichen Zeit die Daten es gut geht, ist das Problem, wenn der Benutzer keine Daten zur Abfrage benötigt und die anderen benötigt, geht es schief.

Wenn ich suche, ohne Daten in jDateChooser zu setzen, ist der Fehler eine NullPointerException, ich habe versucht, viele Beiträge mit diesem Fehler zu lesen, aber niemand hat mir geholfen!

Dies ist der Fehler:

run: 
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException 
    at java.util.Calendar.setTime(Calendar.java:1770) 
    at java.text.SimpleDateFormat.format(SimpleDateFormat.java:943) 
    at java.text.SimpleDateFormat.format(SimpleDateFormat.java:936) 
    at java.text.DateFormat.format(DateFormat.java:345) 
    at projeto_mitjavilla_ricardo.ListarVenda.jTextFieldPorArtigoKeyReleased(ListarVenda.java:2266) 
    at projeto_mitjavilla_ricardo.ListarVenda.access$200(ListarVenda.java:28) 
    at projeto_mitjavilla_ricardo.ListarVenda$4.keyReleased(ListarVenda.java:155) 
    at java.awt.Component.processKeyEvent(Component.java:6496) 
    at javax.swing.JComponent.processKeyEvent(JComponent.java:2832) 
    at java.awt.Component.processEvent(Component.java:6312) 
    at java.awt.Container.processEvent(Container.java:2236) 
    at java.awt.Component.dispatchEventImpl(Component.java:4891) 
    at java.awt.Container.dispatchEventImpl(Container.java:2294) 
    at java.awt.Component.dispatchEvent(Component.java:4713) 
    (...) 

jemand Hoffnung kann verstehen, was das Problem ist und es herausfinden, wenn jemand versteht nicht, was ich tun will, kann man mich fragen, ich werde versuchen, Antwort der beste Weg, den ich kann.

p.s Dies ist das erste Mal, dass ich etwas in einem Forum posten, also wenn ich etwas falsch gemacht habe, in diesem Forum zu posten, bitte sag es mir und ich versuche es besser.