Exception in thread "AWT-EventQueue-0" java.lang.NumberFormatException: null

F

fragen1985

Mitglied
Hallo ,

ich schreibe mein erster Gui :lol: und daher keine Größe Erfahrung,

mein Code Lautet

Java: 
package MathematischeRechnungen;

import java.awt.BorderLayout;
import java.awt.Component;
import java.awt.Container;
import java.awt.Dimension;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.BorderFactory;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JTextArea;
import javax.swing.JTextField;
import MathematischeRechnungen.XQuadratBerechnung;

public class MainWindow extends JFrame implements ActionListener {
    
    /**
     * 
     */
    private static final long serialVersionUID = 1L;
    public static String zahl1;
    public static String zahl2;
    public static  String zahl3;
    
    static XQuadratBerechnung mainB = new XQuadratBerechnung();
    //public static String[] results;
    
    
    JLabel noThing1 = new JLabel("");
    JLabel noThing2 = new JLabel("");
    JLabel noThing3 = new JLabel("");
    JLabel noThing4 = new JLabel("");
    JLabel x2 = new JLabel(" X² ");
    JLabel x1 = new JLabel(" X ");
    JLabel plus1 = new JLabel("  +  ");
    JLabel plus2 = new JLabel("  +  ");
    JLabel equal = new JLabel("  =  ");

    JTextField x2Zahl = new JTextField();
    JTextField x1Zahl = new JTextField();
    JTextField aZahl = new JTextField();
    JTextField bZahl = new JTextField();

    JButton cal = new JButton("Calculate");

    public MainWindow() {
        // TODO Auto-generated constructor stub
        super(" Calculate Programm ");
        initComponents();
        this.addListeners();
    }
    
    
    private static void resultat() {
        JFrame Result = new JFrame("Result");
        Result.setLayout(new GridLayout(2, 0));
        
        Result.add(new JLabel(" X1 = " + MainWindow.Berechnung()[0]));
        Result.add(new JLabel(" X2 = " + MainWindow.Berechnung()[1]));
                
        Result.setLocation(400, 400);
        Result.setPreferredSize(new Dimension(160, 100)); 
        Result.setVisible(true);
        Result.pack();
    }

    private void initComponents() {

        Container c = this.getContentPane();
        GridBagLayout gbl = new GridBagLayout();
        c.setLayout(gbl);

        // x y w h wx wy
        this.addComponent(c, gbl, new JLabel("" + "Example : X²"), 0, 0, 0, 1,
                1.0, 1.0);
        this.addComponent(c, gbl, new JLabel("" + " + "), 3, 0, 0, 1, 1.0, 1.0);
        this.addComponent(c, gbl, new JLabel("" + " 4 "), 4, 0, 0, 1, 1.0, 1.0);
        this.addComponent(c, gbl, new JLabel("" + " X "), 5, 0, 0, 1, 1.0, 1.0);
        this.addComponent(c, gbl, new JLabel("" + " + "), 6, 0, 0, 1, 1.0, 1.0);
        this.addComponent(c, gbl, new JLabel("" + " 4 "), 7, 0, 0, 1, 1.0, 1.0);
        this.addComponent(c, gbl, new JLabel("" + " = "), 8, 0, 0, 1, 1.0, 1.0);
        this.addComponent(c, gbl, new JLabel("" + " 0 "), 9, 0, 0, 1, 1.0, 1.0);
        this.addComponent(c, gbl, new JLabel("" + " "), 1, 1, 0, 2, 1.0, 1.0);
        this.addComponent(c, gbl, new JLabel("" + " "), 2, 1, 0, 2, 1.0, 1.0);
        this.addComponent(c, gbl, new JLabel("" + " "), 3, 1, 0, 2, 1.0, 1.0);
        this.addComponent(c, gbl, new JLabel("" + " "), 4, 1, 0, 2, 1.0, 1.0);
        this.addComponent(c, gbl, new JLabel("" + " "), 5, 1, 0, 2, 1.0, 1.0);
        this.addComponent(c, gbl, new JLabel("" + " "), 6, 1, 0, 2, 1.0, 1.0);
        this.addComponent(c, gbl, new JLabel("" + " "), 7, 1, 0, 2, 1.0, 1.0);
        this.addComponent(c, gbl, new JLabel("" + " "), 8, 1, 0, 2, 1.0, 1.0);
        this.addComponent(c, gbl, new JLabel("" + " "), 9, 1, 0, 3, 1.0, 1.0);

        this.addComponent(c, gbl, this.x2Zahl, 0, 3, 1, 1, 1.0, 1.0);
        this.x2Zahl.setBorder(BorderFactory.createEtchedBorder());
        this.addComponent(c, gbl, this.noThing2, 1, 3, 1, 1, 1.0, 1.0);
        this.x2.setPreferredSize(new Dimension(5, 5));
        this.addComponent(c, gbl, this.x2, 2, 3, 1, 1, 1.0, 1.0);

        this.addComponent(c, gbl, this.plus1, 3, 3, 1, 1, 1.0, 1.0);
        this.addComponent(c, gbl, this.x1Zahl, 4, 3, 1, 1, 1.0, 1.0);
        this.x1Zahl.setBorder(BorderFactory.createEtchedBorder());
        this.addComponent(c, gbl, this.x1, 5, 3, 1, 1, 1.0, 1.0);
        this.addComponent(c, gbl, this.plus2, 6, 3, 1, 1, 1.0, 1.0);
        this.addComponent(c, gbl, this.aZahl, 7, 3, 1, 1, 1.0, 1.0);
        this.aZahl.setBorder(BorderFactory.createEtchedBorder());
        this.addComponent(c, gbl, this.equal, 8, 3, 1, 1, 1.0, 1.0);
        this.bZahl.setBorder(BorderFactory.createEtchedBorder());
        this.addComponent(c, gbl, this.bZahl, 9, 3, 1, 1, 1.0, 1.0);

        this.addComponent(c, gbl, new JLabel("" + " "), 1, 4, 0, 2, 1.0, 1.0);
        this.addComponent(c, gbl, new JLabel("" + " "), 2, 4, 0, 2, 1.0, 1.0);
        this.addComponent(c, gbl, new JLabel("" + " "), 3, 4, 0, 2, 1.0, 1.0);
        this.addComponent(c, gbl, new JLabel("" + " "), 4, 4, 0, 2, 1.0, 1.0);
        this.addComponent(c, gbl, new JLabel("" + " "), 5, 4, 0, 2, 1.0, 1.0);
        this.addComponent(c, gbl, new JLabel("" + " "), 6, 4, 0, 2, 1.0, 1.0);
        this.addComponent(c, gbl, new JLabel("" + " "), 7, 4, 0, 2, 1.0, 1.0);
        this.addComponent(c, gbl, new JLabel("" + " "), 8, 4, 0, 2, 1.0, 1.0);
        this.addComponent(c, gbl, new JLabel("" + " "), 9, 4, 0, 3, 1.0, 1.0);
        this.addComponent(c, gbl, this.cal, 1, 20, 8, 1, 1.0, 1.0);

        this.setLocation(255, 255);
        this.setPreferredSize(new Dimension(400, 130)); // hehe, du hast...

        this.setVisible(true);
        this.pack();
    }

    void addComponent(Container cont, GridBagLayout gbl, Component c, int x,
            int y, int width, int height, double weightx, double weighty) {
        GridBagConstraints gbc = new GridBagConstraints();
        gbc.fill = GridBagConstraints.BOTH;
        gbc.gridx = x;
        gbc.gridy = y;
        gbc.gridwidth = width;
        gbc.gridheight = height;
        gbc.weightx = weightx;
        gbc.weighty = weighty;
        gbl.setConstraints(c, gbc);
        cont.add(c);
    }

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        MainWindow s = new MainWindow();
        

    }

    @Override
    public void actionPerformed(ActionEvent e) {
        // TODO Auto-generated method stub
        if (e.getSource().equals(this.x2Zahl)) {
            
            try {
                MainWindow.zahl1 = this.x2Zahl.getSelectedText();

            } catch (NumberFormatException exc) {
                //ignore
            }
        }
        if (e.getSource().equals(this.x1Zahl)) {
            MainWindow.zahl2 = this.x1Zahl.getSelectedText();
        }
        if (e.getSource().equals(this.aZahl)) {
            MainWindow.zahl3 = this.aZahl.getSelectedText();
        }

        if (e.getSource().equals(this.cal)) {
                MainWindow.resultat();
                
            
            
            
        }
    }

    private void addListeners() {
        this.cal.addActionListener(this);
        this.x2Zahl.addActionListener(this);
        this.x1Zahl.addActionListener(this);
        this.aZahl.addActionListener(this);
        this.bZahl.addActionListener(this);
    }

    public static String[] Berechnung(){
        int d = Integer.parseInt(MainWindow.zahl1);
        int c = Integer.parseInt(MainWindow.zahl2);
        int e = Integer.parseInt(MainWindow.zahl3);
        // Test fuer alle Zahlen
        if (
        d == 0 || 
        c == 0 || 
        e == 0) {
            throw new IllegalArgumentException("Bitte Zahlen Angabe kontrollieren");
        }
        
        // dieser Fall ist für x^2 ist nicht 0
        if (
        Integer.parseInt(MainWindow.zahl1) > 1 || 
        Integer.parseInt(MainWindow.zahl1) < 0) {
            
        c = c /d;
            
        e = e / d;
        }
        
        
        int x = - c;
        
        // der Fall fuer x1 < 0
        if (x > 0) {
            for (int i = 1; i <= x; i++) {
                for (int j = 1; j <= i; j++) {
                    if ( i + j == x && i * j == 
        Integer.parseInt(MainWindow.zahl3)) {
                        String[] results = {Integer.toString(i),Integer.toString(j)};
                        return results;
                    }
                }
            }
        }
        
     // der Fall fuer x1 > 0
        if (x < 0) {
            for (int i = 1; i <= -x; i++) {
                for (int j = 1; j <= i; j++) {
                    if ( i + j == -x && i * j == 
        Integer.parseInt(MainWindow.zahl3)) {
                        String[] results = {Integer.toString(-i),Integer.toString(-j)};
                        return results;
                    }
                }
            }
        }
            
        String[] error = {"ERROR"}; 
        return  error;
    }
}

Danke :rtfm:
 
Wäre schön, wenn du die Zeile angeben könntest, wo der Fehler auftritt.
Selbst ausprobieren kann ich das Programm nicht, weil ich keine Klasse XQuadratBerechnung habe.
 
Exception in thread "AWT-EventQueue-0" java.lang.NumberFormatException: null
at java.lang.Integer.parseInt(Unknown Source)
at java.lang.Integer.parseInt(Unknown Source)
at MathematischeRechnungen.MainWindow.Berechnung(MainWindow.java:195)
at MathematischeRechnungen.MainWindow.resultat(MainWindow.java:64)
at MathematischeRechnungen.MainWindow.actionPerformed(MainWindow.java:178)
at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)
at javax.swing.AbstractButton$Handler.actionPerformed(Unknown Source)
at javax.swing.DefaultButtonModel.fireActionPerformed(Unknown Source)
at javax.swing.DefaultButtonModel.setPressed(Unknown Source)
at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(Unknown Source)
at java.awt.Component.processMouseEvent(Unknown Source)
at javax.swing.JComponent.processMouseEvent(Unknown Source)
at java.awt.Component.processEvent(Unknown Source)
at java.awt.Container.processEvent(Unknown Source)
at java.awt.Component.dispatchEventImpl(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Window.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)
 
Indem du zum Beispiel Exceptions nicht einfach ignorierst:

fragen1985 hat gesagt.:
[JAVA=163]try {
MainWindow.zahl1 = this.x2Zahl.getSelectedText();

} catch (NumberFormatException exc) {
//ignore
}[/code]
Zum Vergrößern anklicken....
Wenn es an dieser Stelle schief geht (und ich kann nur raten, ob es das tut), dann erfährt niemand etwas davon. Schreib doch zumindest
Java: 
exc.printStackTrace();
in den catch-Block…

Und überhaupt: Warum sollte das eine NumberFormatException geben? zahl1 ist ein String (wobei es ein sehr unglücklich gewählter Bezeichner ist) und was aus getSelectedText() rauskommt, ist auch ein String…
 

Aktuelle Jobs

Neue Themen

Ähnliche Themen

Java memory fehler: Exception in thread "AWT-EventQueue-0" java.lang.OutOfMemoryError: Java heap spa
Antworten: 5
Exception in thread "AWT-EventQueue-0" java.lang.N
Antworten: 4
Exception in thread "AWT-EventQueue-0" java.lang.N
Antworten: 4
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
Antworten: 7
Exception in thread "AWT-EventQueue-0" java.lang.IllegalArgumentException: data must
Antworten: 10

Zurück
Oben