Formatting 如何在java中设置年份之间的格式？

所以我需要一些帮助格式化显示字段

/**
 * Creates new form birthTest
 */
public birthTest() {
    initComponents();
}

/**
 * This method is called from within the constructor to initialize the form.
 * WARNING: Do NOT modify this code. The content of this method is always
 * regenerated by the Form Editor.
 */
@SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">
private void initComponents() {

    wrapper = new javax.swing.JPanel();
    jPanel1 = new javax.swing.JPanel();
    jLabel1 = new javax.swing.JLabel();
    innerWrap = new javax.swing.JPanel();
    monthField = new javax.swing.JTextField();
    dayField = new javax.swing.JTextField();
    yearField = new javax.swing.JTextField();
    jLabel2 = new javax.swing.JLabel();
    jLabel3 = new javax.swing.JLabel();
    jLabel4 = new javax.swing.JLabel();
    ageField = new javax.swing.JTextField();
    birthdayField = new javax.swing.JTextField();
    calculate = new javax.swing.JButton();
    jLabel5 = new javax.swing.JLabel();
    jLabel6 = new javax.swing.JLabel();

    setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
    setTitle("test");

    jLabel1.setText("BirthDay Tester");

    javax.swing.GroupLayout jPanel1Layout = new javax.swing.GroupLayout(jPanel1);
    jPanel1.setLayout(jPanel1Layout);
    jPanel1Layout.setHorizontalGroup(
        jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(jPanel1Layout.createSequentialGroup()
            .addGap(85, 85, 85)
            .addComponent(jLabel1)
            .addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
    );
    jPanel1Layout.setVerticalGroup(
        jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, jPanel1Layout.createSequentialGroup()
            .addContainerGap(15, Short.MAX_VALUE)
            .addComponent(jLabel1)
            .addContainerGap())
    );

    yearField.setToolTipText("Enter a four number year");

    jLabel2.setText("M");

    jLabel3.setText("D");

    jLabel4.setText("Y");

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

    jLabel5.setText("Age");

    jLabel6.setText("Birthday");

    javax.swing.GroupLayout innerWrapLayout = new javax.swing.GroupLayout(innerWrap);
    innerWrap.setLayout(innerWrapLayout);
    innerWrapLayout.setHorizontalGroup(
        innerWrapLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, innerWrapLayout.createSequentialGroup()
            .addContainerGap(16, Short.MAX_VALUE)
            .addComponent(jLabel2)
            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
            .addComponent(monthField, javax.swing.GroupLayout.PREFERRED_SIZE, 40, javax.swing.GroupLayout.PREFERRED_SIZE)
            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
            .addComponent(jLabel3)
            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
            .addComponent(dayField, javax.swing.GroupLayout.PREFERRED_SIZE, 40, javax.swing.GroupLayout.PREFERRED_SIZE)
            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
            .addComponent(jLabel4)
            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
            .addComponent(yearField, javax.swing.GroupLayout.PREFERRED_SIZE, 70, javax.swing.GroupLayout.PREFERRED_SIZE)
            .addGap(11, 11, 11))
        .addGroup(innerWrapLayout.createSequentialGroup()
            .addContainerGap()
            .addGroup(innerWrapLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
                .addComponent(birthdayField, javax.swing.GroupLayout.DEFAULT_SIZE, 67, Short.MAX_VALUE)
                .addComponent(ageField))
            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
            .addGroup(innerWrapLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                .addGroup(innerWrapLayout.createSequentialGroup()
                    .addComponent(jLabel6)
                    .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                    .addComponent(calculate))
                .addGroup(innerWrapLayout.createSequentialGroup()
                    .addComponent(jLabel5)
                    .addGap(0, 0, Short.MAX_VALUE)))
            .addContainerGap())
    );
    innerWrapLayout.setVerticalGroup(
        innerWrapLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, innerWrapLayout.createSequentialGroup()
            .addContainerGap()
            .addGroup(innerWrapLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                .addComponent(monthField, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addComponent(dayField, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addComponent(yearField, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addComponent(jLabel2)
                .addComponent(jLabel3)
                .addComponent(jLabel4))
            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
            .addGroup(innerWrapLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                .addComponent(ageField, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addComponent(jLabel5))
            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
            .addGroup(innerWrapLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                .addComponent(birthdayField, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addComponent(calculate)
                .addComponent(jLabel6))
            .addContainerGap(28, Short.MAX_VALUE))
    );

    javax.swing.GroupLayout wrapperLayout = new javax.swing.GroupLayout(wrapper);
    wrapper.setLayout(wrapperLayout);
    wrapperLayout.setHorizontalGroup(
        wrapperLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
        .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, wrapperLayout.createSequentialGroup()
            .addContainerGap()
            .addComponent(innerWrap, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
            .addContainerGap())
    );
    wrapperLayout.setVerticalGroup(
        wrapperLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(wrapperLayout.createSequentialGroup()
            .addContainerGap()
            .addComponent(jPanel1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
            .addGap(18, 18, 18)
            .addComponent(innerWrap, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
            .addContainerGap(12, Short.MAX_VALUE))
    );

    javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
    getContentPane().setLayout(layout);
    layout.setHorizontalGroup(
        layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addComponent(wrapper, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
    );
    layout.setVerticalGroup(
        layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addComponent(wrapper, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
    );

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

private void calculateActionPerformed(java.awt.event.ActionEvent evt) {                                          
    int month = Integer.parseInt(monthField.getText());
    int day = Integer.parseInt(dayField.getText());
    int year = Integer.parseInt(yearField.getText());
    String birth = monthField.getText() + "/" + dayField.getText() + "/"
                    + yearField.getText();

    DateMidnight birthdate = new DateMidnight(year, month, day);
    DateTime now = new DateTime();
    Years age = Years.yearsBetween(birthdate, now);


    birthdayField.setText(String.valueOf(birth));
    ageField.setText(String.valueOf(age));
}                                         

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

    /* Create and display the form */
    java.awt.EventQueue.invokeLater(new Runnable() {
        public void run() {
            new birthTest().setVisible(true);
        }
    });
}
// Variables declaration - do not modify
private javax.swing.JTextField ageField;
private javax.swing.JTextField birthdayField;
private javax.swing.JButton calculate;
private javax.swing.JTextField dayField;
private javax.swing.JPanel innerWrap;
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.JLabel jLabel6;
private javax.swing.JPanel jPanel1;
private javax.swing.JTextField monthField;
private javax.swing.JPanel wrapper;
private javax.swing.JTextField yearField;
// End of variables declaration

这是我的程序，目前正在运行，它给了我想要接受的结果

年龄输出在输出中有两个字母。我正在使用乔达时间图书馆。我已经读了尽可能多的关于这方面的内容，但我不知道如何格式化输出以删除字母。任何帮助都会很好，谢谢您的时间。

当您尝试像这样将age转换为字符串时，请使用Years.toString方法 有人打电话来。该值被格式化为ISO8601持续时间格式：10年将显示为P10Y

要获得年数，请使用

int age = Years.yearsBetween(birthdate, now).getYears();

并显示该值