Question

我正在尝试根据获得点几何的形状绘制图形并在选择此几何体“bornes”的行时更改它的颜色问题是我每次选择行时都会出现此错误的日志文件：提前谢谢

     Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at com.vividsolutions.jump.workbench.ui.renderer.java2D.Java2DConverter.toShape(Java2DConverter.java:313)
at com.vividsolutions.jump.workbench.ui.plugin.specific.SearchPropertiesPlugin$2.valueChanged(SearchPropertiesPlugin.java:144)
at javax.swing.DefaultListSelectionModel.fireValueChanged(DefaultListSelectionModel.java:167)
at javax.swing.DefaultListSelectionModel.fireValueChanged(DefaultListSelectionModel.java:147)
at javax.swing.DefaultListSelectionModel.fireValueChanged(DefaultListSelectionModel.java:194)
at javax.swing.DefaultListSelectionModel.changeSelection(DefaultListSelectionModel.java:388)
at javax.swing.DefaultListSelectionModel.changeSelection(DefaultListSelectionModel.java:398)
at javax.swing.DefaultListSelectionModel.setSelectionInterval(DefaultListSelectionModel.java:442)
at javax.swing.JTable.changeSelectionModel(JTable.java:2352)
at javax.swing.JTable.changeSelection(JTable.java:2421)
at javax.swing.plaf.basic.BasicTableUI$Handler.adjustSelection(BasicTableUI.java:1085)
at javax.swing.plaf.basic.BasicTableUI$Handler.mousePressed(BasicTableUI.java:1008)
at java.awt.AWTEventMulticaster.mousePressed(AWTEventMulticaster.java:263)
at java.awt.Component.processMouseEvent(Component.java:6294)
at javax.swing.JComponent.processMouseEvent(JComponent.java:3275)
at java.awt.Component.processEvent(Component.java:6062)
at java.awt.Container.processEvent(Container.java:2039)
at java.awt.Component.dispatchEventImpl(Component.java:4660)
at java.awt.Container.dispatchEventImpl(Container.java:2097)
at java.awt.Component.dispatchEvent(Component.java:4488)
at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4575)
at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4233)
at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4166)
at java.awt.Container.dispatchEventImpl(Container.java:2083)
at java.awt.Window.dispatchEventImpl(Window.java:2489)
at java.awt.Component.dispatchEvent(Component.java:4488)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:668)
at java.awt.EventQueue.access$400(EventQueue.java:81)
at java.awt.EventQueue$2.run(EventQueue.java:627)
at java.awt.EventQueue$2.run(EventQueue.java:625)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:87)
at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:98)
at java.awt.EventQueue$3.run(EventQueue.java:641)
at java.awt.EventQueue$3.run(EventQueue.java:639)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:87)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:638)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)

这里是这个错误所关注的代码行，它发生在包含bornes（Name，X，Y）的bornesTable的监听器中

     searchProperties.getBornesTable().getSelectionModel().addListSelectionListener(new ListSelectionListener(){

    @Override
    public void valueChanged(ListSelectionEvent e) {

        try {

            if (search()!= null){
        // here's the line 144 in toShape() method      
            final Shape shape = context.getLayerViewPanel().getViewport().getJava2DConverter().toShape(selectedBornes());
            Color color = Color.yellow;
            Stroke stroke =new BasicStroke(5, BasicStroke.CAP_ROUND,BasicStroke.JOIN_ROUND);
            final Graphics2D graphics = (Graphics2D) context.getLayerViewPanel().getGraphics();
            graphics.setColor(color);
            //graphics.setXORMode(Color.white);
            graphics.setStroke(stroke);
            graphics.fill(shape);

            }
            else
                  JOptionPane.showMessageDialog(null, "vous n'avez pas selectionner une bornes " );

        } catch (NoninvertibleTransformException e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();
        }




    }

   });

这是方法：selectedBornes（）

   public Geometry selectedBornes() {

    if (getSelectedRowIndex()> 0)
    {
     Geometry geometry;
     geometry = searchBorne().get(getSelectedRowIndex()).getGeometry();
     return geometry;
    }
    return null;

}

和方法serchBornes（）这没有问题，但我会发布

   private List<BasicFeature> searchBorne() {

    final List<BasicFeature> basicFeatureBornes = new ArrayList<BasicFeature>();

     for(BasicFeature basicFeature : BornesList) {

                if ( searchProperties.getNumTextField().getText().equals(basicFeature.getString("num")) &&
                        searchProperties.getComplementComboBox().getSelectedItem().equals(basicFeature.getString("complement")))
                    basicFeatureBornes.add(basicFeature);


                    }
     return basicFeatureBornes;

}

和方法getSelectedRowIndex（）这也没问题，但我会发布

    public int getSelectedRowIndex() {

    int row = 0;
     for(int i = 0; i < searchBorne().size() ; i++ ) {

          row = searchProperties.getBornesTable().getSelectedRow();

     }

    return row;

}

Answer 1

final Shape shape = context.getLayerViewPanel().getViewport().getJava2DConverter().toShape(selectedBornes());

在这里，您直接将selectedBornes()值传递给toShape方法，但是您没有检查selectedBornes()值是否为空，因此得到NullPointerException如果未选择RowIndex，请将代码更改为

Goemetry newGometry=selectedBornes();
if (newGometry !=null){
final Shape shape = context.getLayerViewPanel().getViewport().getJava2DConverter().toShape(newGometry);
}

Answer 2

public Geometry selectedBornes() {
    if (getSelectedRowIndex()> 0)
    {
     Geometry geometry;
     geometry = searchBorne().get(getSelectedRowIndex()).getGeometry();
     return geometry;
    }

如果所选索引为0（第一个元素）会发生什么？它返回null并且方法崩溃。如果没有选择任何内容，请添加一个检查来处理案例。

用绘图图法绘制形状？

2 个答案: