NullPointerException

[Christopher90]

Hallo,

ich bin gerade dabei einen Kalender zu programmieren. Allerdings wird bei jedem Ausführen der einzelnen Plus/Minus Methoden eine NullPointerException ausgeworfen. Woran liegt das denn?
Weiterhin gibt es Probleme mit dem Schaltjahr. Auch in Nicht-Schaltjahren gibt es einen 29.2 , wenn man vom 30.März einen Monat nach unten wechselt.

Woran liegt das bzw. wie kann ich es beheben?
Weitere Fehler dürfen natürlich gerne genannt und korrigiert werden.

Vielen Dank für eure Hilfe,

Christopher

Hier die Klassen:

Calendar.java

package mycalendar;

import javax.swing.JTextField;

/**
 *
 * @author christopherbucklein
 */
public class Calendar extends javax.swing.JFrame {

    Time time;
    Writer writer;
    JTextField[] timeFields;

    public Calendar() {
        initComponents();
        time = new Time(dayLabel, monthLabel, yearLabel);

        timeFields = new JTextField[8];
        timeFields[0] = termin1;
        timeFields[1] = termin2;
        timeFields[2] = termin3;
        timeFields[3] = termin4;
        timeFields[4] = termin5;
        timeFields[5] = termin6;
        timeFields[6] = termin7;
        timeFields[7] = termin8;
    }
    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">                          
    private void initComponents() {

        dayLabel = new javax.swing.JLabel();
        yearLabel = new javax.swing.JLabel();
        monthLabel = new javax.swing.JLabel();
        dayPlusLabel = new javax.swing.JLabel();
        monthPlusLabel = new javax.swing.JLabel();
        yearPlusLabel = new javax.swing.JLabel();
        dayMinusLabel = new javax.swing.JLabel();
        monthMinusLabel = new javax.swing.JLabel();
        yearMinusLabel = new javax.swing.JLabel();
        uhrzeitLabel1 = new javax.swing.JLabel();
        uhrzeitLabel2 = new javax.swing.JLabel();
        uhrzeitLabel3 = new javax.swing.JLabel();
        uhrzeitLabel4 = new javax.swing.JLabel();
        uhrzeitLabel5 = new javax.swing.JLabel();
        uhrzeitLabel6 = new javax.swing.JLabel();
        uhrzeitLabel7 = new javax.swing.JLabel();
        uhrzeitLabel8 = new javax.swing.JLabel();
        termin1 = new javax.swing.JTextField();
        termin2 = new javax.swing.JTextField();
        termin3 = new javax.swing.JTextField();
        termin4 = new javax.swing.JTextField();
        termin5 = new javax.swing.JTextField();
        termin6 = new javax.swing.JTextField();
        termin7 = new javax.swing.JTextField();
        termin8 = new javax.swing.JTextField();
        speichernButton = new javax.swing.JButton();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

        dayLabel.setBackground(new java.awt.Color(255, 255, 255));
        dayLabel.setFont(new java.awt.Font("Lucida Grande", 1, 48)); // NOI18N
        dayLabel.setText("1");
        dayLabel.setAlignmentX(1.0F);
        dayLabel.setBorder(javax.swing.BorderFactory.createLineBorder(new java.awt.Color(0, 0, 0)));
        dayLabel.setOpaque(true);

        yearLabel.setBackground(new java.awt.Color(255, 255, 255));
        yearLabel.setFont(new java.awt.Font("Lucida Grande", 1, 48));
        yearLabel.setText("2010");
        yearLabel.setAlignmentX(1.0F);
        yearLabel.setBorder(javax.swing.BorderFactory.createLineBorder(new java.awt.Color(0, 0, 0)));
        yearLabel.setOpaque(true);

        monthLabel.setBackground(new java.awt.Color(255, 255, 255));
        monthLabel.setFont(new java.awt.Font("Lucida Grande", 1, 48));
        monthLabel.setText("1");
        monthLabel.setAlignmentX(1.0F);
        monthLabel.setBorder(javax.swing.BorderFactory.createLineBorder(new java.awt.Color(0, 0, 0)));
        monthLabel.setOpaque(true);

        dayPlusLabel.setBackground(new java.awt.Color(255, 255, 255));
        dayPlusLabel.setText("           +");
        dayPlusLabel.setBorder(javax.swing.BorderFactory.createLineBorder(new java.awt.Color(0, 0, 0)));
        dayPlusLabel.setOpaque(true);
        dayPlusLabel.addMouseListener(new java.awt.event.MouseAdapter() {
            public void mouseClicked(java.awt.event.MouseEvent evt) {
                dayPlusLabelMouseClicked(evt);
            }
        });

        monthPlusLabel.setBackground(new java.awt.Color(255, 255, 255));
        monthPlusLabel.setText("            +");
        monthPlusLabel.setBorder(javax.swing.BorderFactory.createLineBorder(new java.awt.Color(0, 0, 0)));
        monthPlusLabel.setOpaque(true);
        monthPlusLabel.addMouseListener(new java.awt.event.MouseAdapter() {
            public void mouseClicked(java.awt.event.MouseEvent evt) {
                monthPlusLabelMouseClicked(evt);
            }
        });

        yearPlusLabel.setBackground(new java.awt.Color(255, 255, 255));
        yearPlusLabel.setText("              +");
        yearPlusLabel.setBorder(javax.swing.BorderFactory.createLineBorder(new java.awt.Color(0, 0, 0)));
        yearPlusLabel.setOpaque(true);
        yearPlusLabel.addMouseListener(new java.awt.event.MouseAdapter() {
            public void mouseClicked(java.awt.event.MouseEvent evt) {
                yearPlusLabelMouseClicked(evt);
            }
        });

        dayMinusLabel.setBackground(new java.awt.Color(255, 255, 255));
        dayMinusLabel.setText("            -");
        dayMinusLabel.setBorder(javax.swing.BorderFactory.createLineBorder(new java.awt.Color(0, 0, 0)));
        dayMinusLabel.setOpaque(true);
        dayMinusLabel.addMouseListener(new java.awt.event.MouseAdapter() {
            public void mouseClicked(java.awt.event.MouseEvent evt) {
                dayMinusLabelMouseClicked(evt);
            }
        });

        monthMinusLabel.setBackground(new java.awt.Color(255, 255, 255));
        monthMinusLabel.setText("            -");
        monthMinusLabel.setBorder(javax.swing.BorderFactory.createLineBorder(new java.awt.Color(0, 0, 0)));
        monthMinusLabel.setOpaque(true);
        monthMinusLabel.addMouseListener(new java.awt.event.MouseAdapter() {
            public void mouseClicked(java.awt.event.MouseEvent evt) {
                monthMinusLabelMouseClicked(evt);
            }
        });

        yearMinusLabel.setBackground(new java.awt.Color(255, 255, 255));
        yearMinusLabel.setText("              -");
        yearMinusLabel.setBorder(javax.swing.BorderFactory.createLineBorder(new java.awt.Color(0, 0, 0)));
        yearMinusLabel.setOpaque(true);
        yearMinusLabel.addMouseListener(new java.awt.event.MouseAdapter() {
            public void mouseClicked(java.awt.event.MouseEvent evt) {
                yearMinusLabelMouseClicked(evt);
            }
        });

        uhrzeitLabel1.setFont(new java.awt.Font("Lucida Grande", 0, 18)); // NOI18N
        uhrzeitLabel1.setText("0-3");

        uhrzeitLabel2.setFont(new java.awt.Font("Lucida Grande", 0, 18)); // NOI18N
        uhrzeitLabel2.setText("3-6");

        uhrzeitLabel3.setFont(new java.awt.Font("Lucida Grande", 0, 18)); // NOI18N
        uhrzeitLabel3.setText("6-9");

        uhrzeitLabel4.setFont(new java.awt.Font("Lucida Grande", 0, 18)); // NOI18N
        uhrzeitLabel4.setText("12-15");

        uhrzeitLabel5.setFont(new java.awt.Font("Lucida Grande", 0, 18)); // NOI18N
        uhrzeitLabel5.setText("9-12");

        uhrzeitLabel6.setFont(new java.awt.Font("Lucida Grande", 0, 18)); // NOI18N
        uhrzeitLabel6.setText("15-18");

        uhrzeitLabel7.setFont(new java.awt.Font("Lucida Grande", 0, 18)); // NOI18N
        uhrzeitLabel7.setText("18-21");

        uhrzeitLabel8.setFont(new java.awt.Font("Lucida Grande", 0, 18)); // NOI18N
        uhrzeitLabel8.setText("21-24");

        speichernButton.setText("Änderungen speichern");
        speichernButton.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                speichernButtonActionPerformed(evt);
            }
        });

        org.jdesktop.layout.GroupLayout layout = new org.jdesktop.layout.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(org.jdesktop.layout.GroupLayout.LEADING)
            .add(layout.createSequentialGroup()
                .add(74, 74, 74)
                .add(layout.createParallelGroup(org.jdesktop.layout.GroupLayout.LEADING)
                    .add(layout.createSequentialGroup()
                        .add(layout.createParallelGroup(org.jdesktop.layout.GroupLayout.TRAILING)
                            .add(uhrzeitLabel4)
                            .add(uhrzeitLabel7)
                            .add(uhrzeitLabel2)
                            .add(uhrzeitLabel5)
                            .add(uhrzeitLabel3)
                            .add(uhrzeitLabel1)
                            .add(uhrzeitLabel6)
                            .add(uhrzeitLabel8))
                        .add(33, 33, 33)
                        .add(layout.createParallelGroup(org.jdesktop.layout.GroupLayout.TRAILING, false)
                            .add(org.jdesktop.layout.GroupLayout.LEADING, termin1, org.jdesktop.layout.GroupLayout.DEFAULT_SIZE, 276, Short.MAX_VALUE)
                            .add(org.jdesktop.layout.GroupLayout.LEADING, termin2, org.jdesktop.layout.GroupLayout.DEFAULT_SIZE, 276, Short.MAX_VALUE)
                            .add(org.jdesktop.layout.GroupLayout.LEADING, termin3, org.jdesktop.layout.GroupLayout.DEFAULT_SIZE, 276, Short.MAX_VALUE)
                            .add(org.jdesktop.layout.GroupLayout.LEADING, termin4, org.jdesktop.layout.GroupLayout.DEFAULT_SIZE, 276, Short.MAX_VALUE)
                            .add(org.jdesktop.layout.GroupLayout.LEADING, termin5, org.jdesktop.layout.GroupLayout.DEFAULT_SIZE, 276, Short.MAX_VALUE)
                            .add(org.jdesktop.layout.GroupLayout.LEADING, termin6, org.jdesktop.layout.GroupLayout.DEFAULT_SIZE, 276, Short.MAX_VALUE)
                            .add(org.jdesktop.layout.GroupLayout.LEADING, termin7, org.jdesktop.layout.GroupLayout.DEFAULT_SIZE, 276, Short.MAX_VALUE)
                            .add(org.jdesktop.layout.GroupLayout.LEADING, termin8, org.jdesktop.layout.GroupLayout.DEFAULT_SIZE, 276, Short.MAX_VALUE)
                            .add(org.jdesktop.layout.GroupLayout.LEADING, speichernButton, org.jdesktop.layout.GroupLayout.DEFAULT_SIZE, org.jdesktop.layout.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
                        .addContainerGap())
                    .add(layout.createSequentialGroup()
                        .add(layout.createParallelGroup(org.jdesktop.layout.GroupLayout.TRAILING, false)
                            .add(dayPlusLabel, org.jdesktop.layout.GroupLayout.DEFAULT_SIZE, org.jdesktop.layout.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                            .add(org.jdesktop.layout.GroupLayout.LEADING, dayMinusLabel, org.jdesktop.layout.GroupLayout.DEFAULT_SIZE, org.jdesktop.layout.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                            .add(org.jdesktop.layout.GroupLayout.LEADING, dayLabel, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE, 112, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE))
                        .add(layout.createParallelGroup(org.jdesktop.layout.GroupLayout.LEADING)
                            .add(layout.createSequentialGroup()
                                .add(12, 12, 12)
                                .add(layout.createParallelGroup(org.jdesktop.layout.GroupLayout.LEADING)
                                    .add(monthLabel, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE, 112, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE)
                                    .add(monthPlusLabel, org.jdesktop.layout.GroupLayout.DEFAULT_SIZE, 112, Short.MAX_VALUE)))
                            .add(layout.createSequentialGroup()
                                .addPreferredGap(org.jdesktop.layout.LayoutStyle.UNRELATED)
                                .add(monthMinusLabel, org.jdesktop.layout.GroupLayout.DEFAULT_SIZE, 110, Short.MAX_VALUE)))
                        .addPreferredGap(org.jdesktop.layout.LayoutStyle.UNRELATED)
                        .add(layout.createParallelGroup(org.jdesktop.layout.GroupLayout.LEADING)
                            .add(yearLabel)
                            .add(yearPlusLabel, org.jdesktop.layout.GroupLayout.DEFAULT_SIZE, 130, Short.MAX_VALUE)
                            .add(yearMinusLabel, org.jdesktop.layout.GroupLayout.DEFAULT_SIZE, 130, Short.MAX_VALUE))
                        .add(76, 76, 76))))
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(org.jdesktop.layout.GroupLayout.LEADING)
            .add(layout.createSequentialGroup()
                .add(30, 30, 30)
                .add(layout.createParallelGroup(org.jdesktop.layout.GroupLayout.LEADING)
                    .add(layout.createSequentialGroup()
                        .add(monthPlusLabel)
                        .addPreferredGap(org.jdesktop.layout.LayoutStyle.UNRELATED)
                        .add(monthLabel, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE, 112, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE))
                    .add(layout.createSequentialGroup()
                        .add(layout.createParallelGroup(org.jdesktop.layout.GroupLayout.BASELINE)
                            .add(dayPlusLabel)
                            .add(yearPlusLabel))
                        .addPreferredGap(org.jdesktop.layout.LayoutStyle.UNRELATED)
                        .add(layout.createParallelGroup(org.jdesktop.layout.GroupLayout.BASELINE)
                            .add(dayLabel, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE, 112, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE)
                            .add(yearLabel, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE, 112, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE))
                        .add(18, 18, 18)
                        .add(layout.createParallelGroup(org.jdesktop.layout.GroupLayout.BASELINE)
                            .add(dayMinusLabel)
                            .add(monthMinusLabel)
                            .add(yearMinusLabel))))
                .add(18, 18, 18)
                .add(layout.createParallelGroup(org.jdesktop.layout.GroupLayout.BASELINE)
                    .add(uhrzeitLabel1)
                    .add(termin1, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE, org.jdesktop.layout.GroupLayout.DEFAULT_SIZE, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE))
                .addPreferredGap(org.jdesktop.layout.LayoutStyle.RELATED)
                .add(layout.createParallelGroup(org.jdesktop.layout.GroupLayout.BASELINE)
                    .add(termin2, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE, org.jdesktop.layout.GroupLayout.DEFAULT_SIZE, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE)
                    .add(uhrzeitLabel2))
                .addPreferredGap(org.jdesktop.layout.LayoutStyle.RELATED)
                .add(layout.createParallelGroup(org.jdesktop.layout.GroupLayout.BASELINE)
                    .add(uhrzeitLabel3)
                    .add(termin3, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE, org.jdesktop.layout.GroupLayout.DEFAULT_SIZE, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE))
                .addPreferredGap(org.jdesktop.layout.LayoutStyle.RELATED)
                .add(layout.createParallelGroup(org.jdesktop.layout.GroupLayout.BASELINE)
                    .add(uhrzeitLabel5)
                    .add(termin4, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE, org.jdesktop.layout.GroupLayout.DEFAULT_SIZE, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE))
                .addPreferredGap(org.jdesktop.layout.LayoutStyle.RELATED)
                .add(layout.createParallelGroup(org.jdesktop.layout.GroupLayout.BASELINE)
                    .add(termin5, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE, org.jdesktop.layout.GroupLayout.DEFAULT_SIZE, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE)
                    .add(uhrzeitLabel4))
                .addPreferredGap(org.jdesktop.layout.LayoutStyle.RELATED)
                .add(layout.createParallelGroup(org.jdesktop.layout.GroupLayout.BASELINE)
                    .add(uhrzeitLabel6)
                    .add(termin6, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE, org.jdesktop.layout.GroupLayout.DEFAULT_SIZE, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE))
                .addPreferredGap(org.jdesktop.layout.LayoutStyle.RELATED)
                .add(layout.createParallelGroup(org.jdesktop.layout.GroupLayout.BASELINE)
                    .add(termin7, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE, org.jdesktop.layout.GroupLayout.DEFAULT_SIZE, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE)
                    .add(uhrzeitLabel7))
                .addPreferredGap(org.jdesktop.layout.LayoutStyle.RELATED)
                .add(layout.createParallelGroup(org.jdesktop.layout.GroupLayout.TRAILING)
                    .add(uhrzeitLabel8)
                    .add(termin8, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE, org.jdesktop.layout.GroupLayout.DEFAULT_SIZE, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE))
                .addPreferredGap(org.jdesktop.layout.LayoutStyle.RELATED, 20, Short.MAX_VALUE)
                .add(speichernButton))
        );

        pack();
    }// </editor-fold>                        

    private void dayPlusLabelMouseClicked(java.awt.event.MouseEvent evt) {                                          
        int[] array = time.dayPlusMethod();
        dayLabel.setText(array[0]+"");
        monthLabel.setText(array[1]+"");
        yearLabel.setText(array[2]+"");
        writer.read(dayLabel.getText(), monthLabel.getText(), yearLabel.getText(), timeFields);
    }                                         

    private void monthPlusLabelMouseClicked(java.awt.event.MouseEvent evt) {                                            
        int[] array = time.monthPlusMethod();
        dayLabel.setText(array[0]+"");
        monthLabel.setText(array[1]+"");
        yearLabel.setText(array[2]+"");
        writer.read(dayLabel.getText(), monthLabel.getText(), yearLabel.getText(), timeFields);
    }                                           

    private void yearPlusLabelMouseClicked(java.awt.event.MouseEvent evt) {                                           
        int jahr = time.yearPlusMethod();
        yearLabel.setText(jahr+"");
        writer.read(dayLabel.getText(), monthLabel.getText(), yearLabel.getText(), timeFields);
    }                                          

    private void dayMinusLabelMouseClicked(java.awt.event.MouseEvent evt) {                                           
        int[] array = time.dayMinusMethod();
        dayLabel.setText(array[0]+"");
        monthLabel.setText(array[1]+"");
        yearLabel.setText(array[2]+"");
        writer.read(dayLabel.getText(), monthLabel.getText(), yearLabel.getText(), timeFields);
    }                                          

    private void monthMinusLabelMouseClicked(java.awt.event.MouseEvent evt) {                                             
        int[] array = time.monthMinusMethod();
        dayLabel.setText(array[0]+"");
        monthLabel.setText(array[1]+"");
        yearLabel.setText(array[2]+"");
        writer.read(dayLabel.getText(), monthLabel.getText(), yearLabel.getText(), timeFields);
    }                                            

    private void yearMinusLabelMouseClicked(java.awt.event.MouseEvent evt) {                                            
        int jahr = time.yearMinusMethod();
        yearLabel.setText(jahr+"");
        writer.read(dayLabel.getText(), monthLabel.getText(), yearLabel.getText(), timeFields);
    }                                           

    private void speichernButtonActionPerformed(java.awt.event.ActionEvent evt) {                                                
        writer = new Writer(termin1, termin2, termin3, termin4, termin5, termin6, termin7, termin8);
        writer.write(dayLabel.getText(), monthLabel.getText(), yearLabel.getText());
    }                                               

    /**
     * @param args the command line arguments
     */
    public static void main(String args[]) {
        java.awt.EventQueue.invokeLater(new Runnable() {

            public void run() {
                new Calendar().setVisible(true);
            }
        });
    }
    // Variables declaration - do not modify                     
    public javax.swing.JLabel dayLabel;
    private javax.swing.JLabel dayMinusLabel;
    private javax.swing.JLabel dayPlusLabel;
    public javax.swing.JLabel monthLabel;
    private javax.swing.JLabel monthMinusLabel;
    private javax.swing.JLabel monthPlusLabel;
    private javax.swing.JButton speichernButton;
    private javax.swing.JTextField termin1;
    private javax.swing.JTextField termin2;
    private javax.swing.JTextField termin3;
    private javax.swing.JTextField termin4;
    private javax.swing.JTextField termin5;
    private javax.swing.JTextField termin6;
    private javax.swing.JTextField termin7;
    private javax.swing.JTextField termin8;
    private javax.swing.JLabel uhrzeitLabel1;
    private javax.swing.JLabel uhrzeitLabel2;
    private javax.swing.JLabel uhrzeitLabel3;
    private javax.swing.JLabel uhrzeitLabel4;
    private javax.swing.JLabel uhrzeitLabel5;
    private javax.swing.JLabel uhrzeitLabel6;
    private javax.swing.JLabel uhrzeitLabel7;
    private javax.swing.JLabel uhrzeitLabel8;
    public javax.swing.JLabel yearLabel;
    private javax.swing.JLabel yearMinusLabel;
    private javax.swing.JLabel yearPlusLabel;
    // End of variables declaration                   
}

Hier die Time.java

package mycalendar;

import javax.swing.*;

/**
 *
 * @author christopherbucklein
 */
public class Time {

    int calendar[] = new int[3];

    int dpm[] = new int[12];

    public Time(JLabel dayLabel, JLabel monthLabel, JLabel yearLabel) {

        calendar[0] = Integer.parseInt(dayLabel.getText());
        calendar[1] = Integer.parseInt(monthLabel.getText());
        calendar[2] = Integer.parseInt(yearLabel.getText());

        dpm[0] = 31;
        dpm[1] = 28;
        dpm[2] = 31;
        dpm[3] = 30;
        dpm[4] = 31;
        dpm[5] = 30;
        dpm[6] = 31;
        dpm[7] = 31;
        dpm[8] = 30;
        dpm[9] = 31;
        dpm[10] = 30;
        dpm[11] = 31;

    }

    public int[] dayPlusMethod() {
       if(calendar[2] % 4 == 0)
            {
            dpm[1] = 29;
        }

        calendar[0]++;

        if (calendar[0] > 31 && calendar[1] == 12) {
            calendar[0] = 1;
            calendar[1] = 1;
            calendar[2]++;
        }
        
        if (calendar[0] > dpm[calendar[1] - 1])
            {
            calendar[0] = 1;
            calendar[1]++;
            }

        return calendar;

    }

    public int[] monthPlusMethod() {
        calendar[1]++;
        if (calendar[1] > 12) {
            calendar[1] = 1;
            calendar[2]++;
        }
        if (calendar[0] > dpm[calendar[1] - 1])
            {
            calendar[0] = dpm[calendar[1] - 1];
            }
       
        return calendar;
    }

    public int yearPlusMethod() {
        calendar[2]++;
        return calendar[2];
    }
    public int[] dayMinusMethod() {
        calendar[0]--;
        if (calendar[0] < 1 && calendar[1] == 1) {
            calendar[0] = 31;
            calendar[1] = 12;
            calendar[2]--;
            }

        if (calendar[0] > dpm[calendar[1] - 1])
            {
            calendar[0] = dpm[calendar[1] - 1];
            }

        if (calendar[0] < 1){
            calendar[0] = dpm[calendar[1] - 2];
            calendar[1]--;
        }
        return calendar;
    }

    public int[] monthMinusMethod() {
        calendar[1]--;
        if (calendar[1] < 1) {
            calendar[1] = 12;
            calendar[2]--;
        }
        if (calendar[0] > dpm[calendar[1] - 1])
            {
            calendar[0] = dpm[calendar[1] - 1];
            }

       return calendar;
    }

    public int yearMinusMethod() {
        calendar[2]--;
        return calendar[2];
    }

}

 

[Landei]

NullPointerExceptions kommen daher, dass man versucht, an einer null-Referenz eine Methode aufzurufen.

Schau nach, in welcher Zeile die Exception fliegt, und lass dir genau davor alle Null-Kandidaten mit System.out.println ausgeben, dann bist du schonal einen Schritt weiter.

 

[Thief]

Poste doch mal den Stacktrace, da stehts wohl drin...

 

[Christopher90]

Und hier die Writer.java

package mycalendar;

import java.io.*;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.swing.*;
/**
 *
 * @author christopherbucklein
 */
public class Writer {

    String[] dates = new String[8];

    public Writer(JTextField label1, JTextField label2, JTextField label3, JTextField label4, JTextField label5, JTextField label6, JTextField label7, JTextField label8) {
        dates[0] = label1.getText();
        dates[1] = label2.getText();
        dates[2] = label3.getText();
        dates[3] = label4.getText();
        dates[4] = label5.getText();
        dates[5] = label6.getText();
        dates[6] = label7.getText();
        dates[7] = label8.getText();
    }

    public void write(String day, String month, String year) {
        try {
            String dateiname = day + month + year + ".txt";
            BufferedWriter writer = new BufferedWriter(new FileWriter(dateiname));
            for (int i = 0; i < dates.length; i++) {
                writer.write(dates[i]);
                writer.newLine();
            }
            writer.close();
        } catch (IOException ex) {
            Logger.getLogger(Writer.class.getName()).log(Level.SEVERE, null, ex);

        }

    }

    public void read(String day, String month, String year, JTextField[] fields) {
        String dateiname = day + month + year + ".txt";
        String text;
        try {
            BufferedReader reader = new BufferedReader(new FileReader(dateiname));
            for (int i = 0; i < fields.length; i++) {
                text = reader.readLine();
                fields[i].setText(text);
            }
            reader.close();
        } catch (Exception ex) {
            for (int i = 0; i < fields.length; i++) {
                fields[i].setText("");
        }


    }
}
}

 

[Christopher90]

Ausgeworfen wird folgendes:

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
        at mycalendar.Calendar.monthPlusLabelMouseClicked(Calendar.java:317)
        at mycalendar.Calendar.access$100(Calendar.java:19)
        at mycalendar.Calendar$2.mouseClicked(Calendar.java:118)
        at java.awt.Component.processMouseEvent(Component.java:6351)
        at javax.swing.JComponent.processMouseEvent(JComponent.java:3267)
        at java.awt.Component.processEvent(Component.java:6113)
        at java.awt.Container.processEvent(Container.java:2085)
        at java.awt.Component.dispatchEventImpl(Component.java:4714)
        at java.awt.Container.dispatchEventImpl(Container.java:2143)
        at java.awt.Component.dispatchEvent(Component.java:4544)
        at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4618)
        at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4291)
        at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4212)
        at java.awt.Container.dispatchEventImpl(Container.java:2129)
        at java.awt.Window.dispatchEventImpl(Window.java:2478)
        at java.awt.Component.dispatchEvent(Component.java:4544)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:635)
        at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:296)
        at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:211)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:201)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:196)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:188)
        at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)

Exemplarisch für monthPlusMethod

 

[Thief]

Stacktrace, nicht Sourcecode *g* Der war ja vorhin schon angehangen.

 

[Thief]

dein writer ist null

 

[Christopher90]

...

Wenn nur alles so einfach wäre
Vielen Dank!

Ich hatte ihn mal initialisiert, aber dann hatte ich im Konstruktor noch ein bisschen war umgestellt, da ist er wahrscheinlich verloren gegangen...

Vielen Dank, super, wie schnell mir hier geholfen wurde!

 

[Christopher90]

Hallo,

ich habe noch einmal die Methoden umgestellt, und bekomme wieder eine NullPointerException, die ich nicht begründen kann...

    public void write(String day, String month, String year) {
        try {
            String dateiname = day + month + year + ".txt";
            BufferedWriter writer = new BufferedWriter(new FileWriter(dateiname));
            for (int i = 0; i < dates.length; i++) {
                writer.write(dates[i]);
                writer.newLine();
            }
            writer.close();
        } catch (IOException ex) {
            Logger.getLogger(Writer.class.getName()).log(Level.SEVERE, null, ex);

        }

    }

 public Calendar() {
        initComponents();
        time = new Time(dayLabel, monthLabel, yearLabel);
        timeFields = new JTextField[8];
        timeFields[0] = termin1;
        timeFields[1] = termin2;
        timeFields[2] = termin3;
        timeFields[3] = termin4;
        timeFields[4] = termin5;
        timeFields[5] = termin6;
        timeFields[6] = termin7;
        timeFields[7] = termin8;
        writer = new Writer(timeFields);
    }

private void speichernButtonActionPerformed(java.awt.event.ActionEvent evt) {                                                

        writer.write(dayLabel.getText(), monthLabel.getText(), yearLabel.getText());
    }

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
        at java.io.Writer.write(Writer.java:140)
        at mycalendar.Writer.write(Writer.java:37)
        at mycalendar.Calendar.speichernButtonActionPerformed(Calendar.java:387)
        at mycalendar.Calendar.access$600(Calendar.java:19)
        at mycalendar.Calendar$7.actionPerformed(Calendar.java:195)
        at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2028)
        at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2351)
        at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:387)
        at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:242)
        at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:236)
        at java.awt.Component.processMouseEvent(Component.java:6348)
        at javax.swing.JComponent.processMouseEvent(JComponent.java:3267)
        at java.awt.Component.processEvent(Component.java:6113)
        at java.awt.Container.processEvent(Container.java:2085)
        at java.awt.Component.dispatchEventImpl(Component.java:4714)
        at java.awt.Container.dispatchEventImpl(Container.java:2143)
        at java.awt.Component.dispatchEvent(Component.java:4544)
        at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4618)
        at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4282)
        at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4212)
        at java.awt.Container.dispatchEventImpl(Container.java:2129)
        at java.awt.Window.dispatchEventImpl(Window.java:2478)
        at java.awt.Component.dispatchEvent(Component.java:4544)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:635)
        at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:296)
        at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:211)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:201)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:196)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:188)
        at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)

Es würde mich sehr freuen, wenn ihr mir noch einmal helfen könntet.

Gruss,

Christopher

 

[Thief]

pack bitte nochmal deinen ganzen source hier rein, von mir aus wieder als .rar /.zip