如何從 JDateChooser 獲取日期並格式化它？

Question

如何從 JDateChooser 獲取日期並格式化它？

JDateChooser實例

private void jDateChooser1PropertyChange(java.beans.PropertyChangeEvent evt) { 
   
   SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");

   String date = sdf.format(jDateChooser1.getDate());
   System.out.println("date:"+ date);
   
}  

我收到如下所示的錯誤

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException: Cannot invoke 
"java.util.Date.getTime()" because "date" is null

at java.base/java.util.Calendar.setTime(Calendar.java:1801)
at java.base/java.text.SimpleDateFormat.format(SimpleDateFormat.java:975)
at java.base/java.text.SimpleDateFormat.format(SimpleDateFormat.java:968)
at java.base/java.text.DateFormat.format(DateFormat.java:375)
at com.mycompany.pos.add_stock_adjustment1.jDateChooser1PropertyChange(add_stock_adjustment1.java:880)
at com.mycompany.pos.add_stock_adjustment1$7.propertyChange(add_stock_adjustment1.java:466)
at java.desktop/java.beans.PropertyChangeSupport.fire(PropertyChangeSupport.java:341)
at java.desktop/java.beans.PropertyChangeSupport.firePropertyChange(PropertyChangeSupport.java:333)
at java.desktop/java.beans.PropertyChangeSupport.firePropertyChange(PropertyChangeSupport.java:266)    

如何修復此錯誤？

Answer 1

private void jDateChooser1PropertyChange(java.beans.PropertyChangeEvent evt) {                                             
   if ("date".equals(evt.getPropertyName())) { 
       SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
       String date = sdf.format(jDateChooser1.getDate());
       System.out.println("date:"+ date);
   }else{
       System.out.println("null");
   } 
} 

現在它正在工作。