NullPointerException when setting text of text field

Question

Can someone please help me because I have to get this project in by the end of tomorrow?

Every time I try and set the text of a text field my program crashes and gives a null pointer exception. How can I overcome this?

Here is sample code where the error also occurred:

package disciplinesys;

public class NewJFrame extends javax.swing.JFrame {

    /** Creates new form NewJFrame */
    public NewJFrame() {
        jTextField1.setText("Yes");
        initComponents();
    }

    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">
    private void initComponents() {

        jTextField1 = new javax.swing.JTextField();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGap(120, 120, 120)
                .addComponent(jTextField1, javax.swing.GroupLayout.PREFERRED_SIZE, 139, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addContainerGap(141, Short.MAX_VALUE))
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGap(116, 116, 116)
                .addComponent(jTextField1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addContainerGap(164, Short.MAX_VALUE))
        );

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

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

    // Variables declaration - do not modify
    private javax.swing.JTextField jTextField1;
    // End of variables declaration

}

Denis Biondic · Accepted Answer · 2011-07-02 11:22:15Z

6

Call jTextField1.setText("Yes"); after the initComponents();

Like this:

/** Creates new form NewJFrame */
public NewJFrame() {
    initComponents();
    jTextField1.setText("Yes");
}

This is because your textfield variable isn't created until the initComponents();

answered Jul 2, 2011 at 11:22

Denis Biondic

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1 Comment

Hovercraft Full Of Eels Over a year ago

And don't use NetBeans to create your Swing code so you'll know what you are doing.

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