我需要帮助。 我正在编写一个具有GUI的程序

Question

The user will enter a number between 1 and 99. I've got most my code written I just can't figure out out to get it to calculate with the calculate button. I could really use some step by step help I'm willing to learn if some one can help me. I'm a very beginner.

package minimumchris;

import javax.swing.JButton;
import javax.swing.JTextField;


public class useri extends javax.swing.JFrame {


    public useri() {
        initComponents();
    }


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

        jScrollPane1 = new javax.swing.JScrollPane();
        jLabel1 = new javax.swing.JLabel();
        jTextField1 = new javax.swing.JTextField();
        jLabel2 = new javax.swing.JLabel();
        jLabel3 = new javax.swing.JLabel();
        jLabel4 = new javax.swing.JLabel();
        jLabel5 = new javax.swing.JLabel();
        jButton1 = new javax.swing.JButton();
        jButton2 = new javax.swing.JButton();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

        jLabel1.setText("enter a number between 1-99");

        jLabel2.setText("quarters");

        jLabel3.setText("dimes");

        jLabel4.setText("nickels");

        jLabel5.setText("pennies");

        jButton1.setText("calculate");
        jButton1.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButton1ActionPerformed(evt);
            }
        });

        jButton2.setText("clear");

        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(layout.createParallelGroup(org.jdesktop.layout.GroupLayout.LEADING)
                    .add(layout.createSequentialGroup()
                        .addContainerGap()
                        .add(jLabel1, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE, 197, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE)
                        .addPreferredGap(org.jdesktop.layout.LayoutStyle.RELATED, org.jdesktop.layout.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                        .add(jTextField1, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE, 47, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE))
                    .add(layout.createSequentialGroup()
                        .add(66, 66, 66)
                        .add(layout.createParallelGroup(org.jdesktop.layout.GroupLayout.LEADING)
                            .add(jLabel5)
                            .add(jLabel4)
                            .add(jLabel3)
                            .add(jLabel2))
                        .add(0, 0, Short.MAX_VALUE)))
                .addContainerGap())
            .add(layout.createSequentialGroup()
                .addContainerGap()
                .add(jButton1, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE, 195, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE)
                .addPreferredGap(org.jdesktop.layout.LayoutStyle.RELATED)
                .add(jButton2, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE, 177, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE)
                .addContainerGap(16, Short.MAX_VALUE))
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(org.jdesktop.layout.GroupLayout.LEADING)
            .add(layout.createSequentialGroup()
                .addContainerGap()
                .add(layout.createParallelGroup(org.jdesktop.layout.GroupLayout.TRAILING)
                    .add(jTextField1, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE, org.jdesktop.layout.GroupLayout.DEFAULT_SIZE, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE)
                    .add(jLabel1))
                .add(32, 32, 32)
                .add(jLabel2)
                .add(18, 18, 18)
                .add(jLabel3)
                .addPreferredGap(org.jdesktop.layout.LayoutStyle.UNRELATED)
                .add(jLabel4)
                .addPreferredGap(org.jdesktop.layout.LayoutStyle.RELATED)
                .add(jLabel5)
                .add(29, 29, 29)
                .add(layout.createParallelGroup(org.jdesktop.layout.GroupLayout.LEADING, false)
                    .add(jButton2, org.jdesktop.layout.GroupLayout.DEFAULT_SIZE, 73, Short.MAX_VALUE)
                    .add(jButton1, org.jdesktop.layout.GroupLayout.DEFAULT_SIZE, org.jdesktop.layout.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
                .addContainerGap(32, Short.MAX_VALUE))
        );

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

    private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                         
        int cntrquart = 0;
        int cntrdimes = 0;
        int cntrpennies = 0;
        int cntrnickels = 0;



         JTextField jTextField=new JTextField(); // initialize textFild
         JButton calculate =jButton1;




       int quarters = Integer.parseInt(jTextField.getText());


        while (quarters >= 25)

        {
           quarters = quarters  - 25;
           cntrquart++;


        }


//dimes 
        int dimes = quarters;


        while (dimes >= 10)

        {
           dimes = dimes  - 10;
           cntrdimes++;
        }



//nickels 
        int nickels = dimes;


        while (nickels >= 5)
        {
           nickels = nickels  - 5;
           cntrnickels++;
        }



//pennies
        int pennies = nickels;


        while (pennies >= 1)
        {
           pennies = pennies  - 1;
           cntrpennies++;
        }
        jLabel2.setText("Quarter" + cntrquart );
        jLabel3.setText("Dimes:" + cntrdimes );
        jLabel4.setText("Nickels:" + cntrnickels );
        jLabel5.setText("Pennies:" + cntrpennies );
    }                                        

    /**
     * @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(useri.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (InstantiationException ex) {
            java.util.logging.Logger.getLogger(useri.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (IllegalAccessException ex) {
            java.util.logging.Logger.getLogger(useri.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (javax.swing.UnsupportedLookAndFeelException ex) {
            java.util.logging.Logger.getLogger(useri.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        }
        //</editor-fold>

        /* Create and display the form */
        java.awt.EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                new useri().setVisible(true);
            }
        });
    }
    // Variables declaration - do not modify                     
    private javax.swing.JButton jButton1;
    private javax.swing.JButton jButton2;
    private javax.swing.JLabel jLabel1;
    private javax.swing.JLabel jLabel2;
    private javax.swing.JLabel jLabel3;
    private javax.swing.JLabel jLabel4;
    private javax.swing.JLabel jLabel5;
    private javax.swing.JScrollPane jScrollPane1;
    private javax.swing.JTextField jTextField1;
    // End of variables declaration                   
}

Answer 1

Problem is you're using a brand new JTextField when "calculate" is pressed:

JTextField jTextField=new JTextField(); // useless
JButton calculate =jButton1; // useless

int quarters = Integer.parseInt(jTextField.getText()); // should use jTextField1 (probably)

Answer 2

Like RC said with the line:

JTextField jTextField=new JTextField();

You are creating a new JTextField object which is not want you want. Since the variables you have are class instances you can refer to them directly as such:

int quaters = Integer.parseInt(jTextField1.getText());

Creating a new variable means entire new distinct set of parameters for that variable and instance-specific data (like whats inside the box of a JTextField ) is not shared. Since you are (presumably) populating the JTextField jTextField1 with text, the text can only be retrieved via calling getText() upon the jTextField1 object itself.

Besides the point but might I suggest using more intuitive variable names and only copying the relevant parts of the code. This helps us find your issue more quickly. Please also make your question title specific to the problem itself, "I need help" isn't going to get you anywhere.

As a final point, your code can be further optimized and simplified if you replace your loops with simple division/mod operations. Instead of:

while (quarters >= 25){
    quarters = quarters  - 25;
    cntrquart++;
}

int dimes = quarters;

//...

do:

cntrlquart = quarters / 25; //Integer division
int dimes = quarters % 25; //Mod operation, remainder of dividing by 25.