addTableModelListener中加入JLabel.setText()就报错，请教，谢谢！

[ycjnx]

关键代码如下：

	private JLabel info_sumJL;//总数信息
........
........
........
	public TabbedPane() {
........
			JLabel info_sumJL=new JLabel(getInfo_sum(sum_zhong,sum_jian,sum_price));
			topicLabel.add(info_sumJL);
			// 为表格数据添加事件监听器
			tableModel.addTableModelListener(new TableModelListener() {
				public void tableChanged(TableModelEvent e) {					
					int type = e.getType();// 获得事件的类型
					int row = e.getFirstRow();// 获得触发此次事件的表格行索引
					int column = e.getColumn();// 获得触发此次事件的表格列索引
					//更改金额小计和neworder_id值时不触发事件，金额小计栏的索引值：6，这行代码很重要，不加狂报错
					if((column==6)||(column==7)||(column==9)) return;
					if (type == TableModelEvent.UPDATE) {
						TableModel model = (TableModel)e.getSource();//自动获取表格模型
				        Object data = model.getValueAt(row, column);						
				        int num=Integer.parseInt(data.toString());//订购数量
						data=model.getValueAt(row,9);//9:订购数量_old
						int num_old=Integer.parseInt(data.toString());
						if(num<0){
							//订购数量不能小于0
							model.setValueAt(num_old+"",row,column);
						}else{
							Object goods_id=model.getValueAt(row,0);//商品ID
							data=model.getValueAt(row,2);//商品单价
							float shop_price = Float.parseFloat(data.toString());
							//修改金额小计一栏的数值
							model.setValueAt((shop_price*num),row,(column+1));
							if(num_old!=num){
								//存储数据							
								int id=Dao.updateNeworder(num+"",user_id,goods_id.toString());
								//修改neworder_id值（有可能是新插入的记录）
								model.setValueAt(id+"",row,(column+2));
								//修改neworder_id值
								model.setValueAt(num+"",row,(column+4));
								if(num==0){
									sum_zhong--;								
								}else if(num_old==0){
									sum_zhong++;
								}
								int num_new=num-num_old;
								sum_jian+=num_new;
								sum_price+=num_new*shop_price;	
								String s=getInfo_sum(sum_zhong,sum_jian,sum_price);
								//System.out.println(s);//这句加上正常输出
								info_sumJL.setText(s);//这句加上就报错
							}
						}
					}					
				}
			});
........
        }
........
	public String getInfo_sum(int sum_zhong,int sum_jian,float sum_price){
		DecimalFormat df = new DecimalFormat(".00");
		return "共 "+sum_zhong+" 种 "+sum_jian+" 件         金额总计："+df.format(sum_price)+" 元";	
	}	

//下面这句加上就报错：
info_sumJL.setText(s);

//下面这句加上正常输出：
System.out.println(s);
//输出的内容：
共 13 种 26 件 金额总计：26.40 元
共 13 种 27 件 金额总计：26.80 元
共 14 种 32 件 金额总计：46.80 元
共 15 种 38 件 金额总计：58.80 元

请高手指点，这代码错在什么地方？正确的该如何写？

[ycjnx]

//下面这句加上就报错： info_sumJL.setText(s); //报错信息： Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException at cn.nxxian.TabbedPane$3.tableChanged(TabbedPane.java:176) at javax.swing.table.AbstractTableModel.fireTableChanged(Unknown Source) at javax.swing.table.AbstractTableModel.fireTableCellUpdated(Unknown Source) at javax.swing.table.DefaultTableModel.setValueAt(Unknown Source) at cn.nxxian.TableSorter.setValueAt(TableSorter.java:280) at javax.swing.JTable.setValueAt(Unknown Source) at javax.swing.JTable.editingStopped(Unknown Source) at javax.swing.AbstractCellEditor.fireEditingStopped(Unknown Source) at javax.swing.DefaultCellEditor$EditorDelegate.stopCellEditing(Unknown Source) at javax.swing.DefaultCellEditor.stopCellEditing(Unknown Source) at javax.swing.JTable$GenericEditor.stopCellEditing(Unknown Source) at javax.swing.plaf.basic.BasicTableUI$Handler.mousePressed(Unknown Source) at java.awt.AWTEventMulticaster.mousePressed(Unknown Source) at java.awt.Component.processMouseEvent(Unknown Source) at javax.swing.JComponent.processMouseEvent(Unknown Source) at java.awt.Component.processEvent(Unknown Source) at java.awt.Container.processEvent(Unknown Source) at java.awt.Component.dispatchEventImpl(Unknown Source) at java.awt.Container.dispatchEventImpl(Unknown Source) at java.awt.Component.dispatchEvent(Unknown Source) at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source) at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source) at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source) at java.awt.Container.dispatchEventImpl(Unknown Source) at java.awt.Window.dispatchEventImpl(Unknown Source) at java.awt.Component.dispatchEvent(Unknown Source) at java.awt.EventQueue.dispatchEventImpl(Unknown Source) at java.awt.EventQueue.access$200(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.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source) at java.awt.EventQueue$4.run(Unknown Source) at java.awt.EventQueue$4.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)

[ycjnx]

info_sumJL是JTable之外的一个成员变量，怎么会触发 .tableChanged()呢？初学，不懂，请指教，谢谢！

[ycjnx]

自撸成功： 把： JLabel info_sumJL=new JLabel(getInfo_sum(sum_zhong,sum_jian,sum_price)); 改成： final JLabel info_sumJL=new JLabel(getInfo_sum(sum_zhong,sum_jian,sum_price));

[ycjnx]

解决了，谢谢，前三回复就结贴！

[haoayuyu]

楼主，解决了吗？