JTextArea没有设置，抛出错误

所以我从数据库中提取信息并将它们放入我的GUI中的字段/框中。JTextArea没有设置，抛出错误

houseText和addressText都是文本字段，它们设置正常，但oInfo是JTextArea，当我尝试设置它时会导致错误。我也尝试使用'追加'，但它没有改变任何东西。任何解决方案

infoHolder = dBStatement.executeQuery("SELECT * FROM House"); 
infoHolder.next(); 

hName = infoHolder.getString("Name"); 
hAddress = infoHolder.getString("Address"); 
numRooms = infoHolder.getInt("numRooms"); 
Type = infoHolder.getString("Type"); 
charge = infoHolder.getString("roomCharge"); 
Access = infoHolder.getString("dAccess"); 
Info = infoHolder.getString("oInfo"); 

// the below print prints all the details to prove that the database has been read correctly. 
System.out.println(hName + " " + hAddress + " " + numRooms + " " + Type + " " + charge + " " + Access + " " + Info); 

houseText.setText(" " + hName); 
addressText.setText(" " + hAddress); 
//roomNumber.setSelectedItem(numRooms); 
//roomType.setSelectedItem(" " + Type); 
//chargeRoom.setSelectedItem(" " + charge); 
//access.setSelectedItem(" " + Access); 
oInfo.setText(Info);

堆栈跟踪：为了完整起见，和其他一些次要的信息

java.lang.NullPointerException at FinalBAndB.initialiseDatabase(FinalBAndB.java:124) 
    at FinalBAndB$1.run(FinalBAndB.java:274) 
    at java.awt.event.InvocationEvent.dispatch(Unknown Source) 
    at java.awt.EventQueue.dispatchEventImpl(Unknown Source) 
    at java.awt.EventQueue.access$400(Unknown Source) at java.awt.EventQueue$3.run(Unknown Source) 
    at java.awt.EventQueue$3.run(Unknown Source) at java.security.AccessController.doPrivileged(Native Method) 
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source) at java.awt.EventQueue.dispatchEvent(Unknown Source) 
    at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source) 
    at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source) 
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source) 
    at java.awt.EventDispatchThread.pumpEvents(Unknown Source) 
    at java.awt.EventDispatchThread.pumpEvents(Unknown Source) 
    at java.awt.EventDispatchThread.run(Unknown Source)

来源

2015-02-06 user3822332

你得到了什么错误，你从哪里调用这段代码？它是一个事件处理程序，一些其他线程？ – npinti 2015-02-06 13:30:11

@npinti我打电话从我的公共静态无效的主要代码。上面的代码在它自己的方法里面，名为initialiseDatabase（）; textfields设置完美，但textarea（oinfo）是问题。我在打印堆栈跟踪的方法上有一个异常处理程序，但它没有任何启发性。 infoHolder是一个结果集。 – user3822332 2015-02-06 13:34:16

什么不启发乔可能会启发杰克。堆栈跟踪不是FYEO。 – laune 2015-02-06 13:53:21

添加答案。

堆栈跟踪：

java.lang.NullPointerException at FinalBAndB.initialiseDatabase(FinalBAndB.java:124) 
    at FinalBAndB$1.run(FinalBAndB.java:274) 
    at java.awt.event.InvocationEvent.dispatch(Unknown Source) 
    at java.awt.EventQueue.dispatchEventImpl(Unknown Source) 
    at java.awt.EventQueue.access$400(Unknown Source) at java.awt.EventQueue$3.run(Unknown Source) 
    at java.awt.EventQueue$3.run(Unknown Source) at java.security.AccessController.doPrivileged(Native Method) 
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source) at java.awt.EventQueue.dispatchEvent(Unknown Source) 
    at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source) 
    at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source) 
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source) 
    at java.awt.EventDispatchThread.pumpEvents(Unknown Source) 
    at java.awt.EventDispatchThread.pumpEvents(Unknown Source) 
    at java.awt.EventDispatchThread.run(Unknown Source)

表明您试图访问一个非初始化的对象。事实证明情况就是如此。

附加信息：与许多其他语言一样，Java使用特定线程来执行其所有UI操作。在Java中，这被称为Event Dispatcher Thread（EDT）。由于您正在更新UI组件的文本，因此您需要确保操作通过EDT的操作环境进行。要做到这一点，通常会回到使用SwingUtilities.invokeLater(Runnable runnable)。请确保您遵循此模式以避免任何跨线程操作的潜在问题。

来源

2015-02-06 14:25:25 npinti

JTextArea没有设置，抛出错误

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