java netbeans java.lang.NullPointerException错误

我正在为我的学术目的开发一个软件。为此，我使用Netbeans IDE、sqlite。当我运行代码时，它会给我以下错误

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at sun.misc.FloatingDecimal.readJavaFormatString(FloatingDecimal.java:1838)
at sun.misc.FloatingDecimal.parseDouble(FloatingDecimal.java:110)
at java.lang.Double.parseDouble(Double.java:538)
at ProductInfo.getProductList(ProductInfo.java:109)
at ProductInfo.Show_Products_In_JTable(ProductInfo.java:126)
at ProductInfo.<init>(ProductInfo.java:44)
at ProductInfo$12.run(ProductInfo.java:658)
at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:311)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:756)
at java.awt.EventQueue.access$500(EventQueue.java:97)
at java.awt.EventQueue$3.run(EventQueue.java:709)
at java.awt.EventQueue$3.run(EventQueue.java:703)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:76)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:726)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)

这是实体类

public class Product {
private int id;
private String name;
private double price;
private String addDate; 
private byte[] picture;


public Product(int pid, String pname, double pprice, String pAddDate, byte[] pimg)
{
    this.id = pid;
    this.name = pname;
    this.price = pprice;
    this.addDate = pAddDate;
    this.picture = pimg;

}

public int getId()
{
    return id;
}

public String getName()
{
    return name;
}

public double getPrice()
{
    return price;
}

public String getAddDate()
{
    return  addDate;
}

public byte[] getImage()
{
    return picture;
}

---

我是一个初学者，不理解错误。有人能帮我解决吗？

调试NullPointerException的启发式方法几乎总是一样的：您应该仔细阅读异常的堆栈跟踪，找到出错的代码行，即引发异常的代码行，然后仔细检查该行，找出哪个变量为null，然后追溯到你的代码，看看原因。相信我，你会一次又一次地碰到这些。将来，请在发布之前搜索该主题，因为这是一个太常见的问题，无法发布另一个NPE问题。因此，您需要研究此行的变量：

ProductInfo.java:109

以查看空值，然后返回搜索以了解原因。请查看在中找到的合适答案，我猜第109行就是这一行：

productList.add（product）。请让我知道这是否正确。如果是这样的话，您将需要了解变量阴影和NullPointerException。另外，请阅读您提供的搜索并尝试，但仍然无法找到解决方法（@hoverfullofeels）
// Variables declaration - do not modify                     
private javax.swing.JTable JTable_Products;
private javax.swing.JButton btn_Image;
private javax.swing.JButton btn_delete;
private javax.swing.JButton btn_first;
private javax.swing.JButton btn_insert;
private javax.swing.JButton btn_last;
private javax.swing.JButton btn_next;
private javax.swing.JButton btn_previous;
private javax.swing.JButton btn_update;
private javax.swing.JPanel jPanel1;
private javax.swing.JScrollPane jScrollPane1;
private javax.swing.JLabel lbl_date;
private javax.swing.JLabel lbl_id;
private javax.swing.JLabel lbl_image;
private javax.swing.JLabel lbl_img;
private javax.swing.JLabel lbl_name;
private javax.swing.JLabel lbl_price;
private datechooser.beans.DateChooserCombo txt_AddDate;
private javax.swing.JTextField txt_id;
private javax.swing.JTextField txt_name;
private javax.swing.JTextField txt_price;
// End of variables declaration                   

public class Product {
private int id;
private String name;
private double price;
private String addDate; 
private byte[] picture;


public Product(int pid, String pname, double pprice, String pAddDate, byte[] pimg)
{
    this.id = pid;
    this.name = pname;
    this.price = pprice;
    this.addDate = pAddDate;
    this.picture = pimg;

}

public int getId()
{
    return id;
}

public String getName()
{
    return name;
}

public double getPrice()
{
    return price;
}

public String getAddDate()
{
    return  addDate;
}

public byte[] getImage()
{
    return picture;
}