[Geotools-gt2-users] SEVERE: Error adding map layer

[Zekeng l. <ken...@ho...>]

Hi,

When I tried to remove the layers from the MapContext, update the layers and 
then add them back to the MapContext, it has the "SEVERE: Error adding map 
layer" problem. It says:
java.lang.NullPointerException
        at 
org.geotools.renderer.j2d.StyledMapRenderer.addLayer(StyledMapRendere
r.java:180)
        at 
org.geotools.renderer.j2d.StyledMapRenderer$1.layerAdded(StyledMapRen
derer.java:135)
        at 
org.geotools.map.DefaultMapContext.fireMapLayerListListenerLayerAdded
(DefaultMapContext.java:701)
        at 
org.geotools.map.DefaultMapContext.addLayers(DefaultMapContext.java:2
62)
        at SpearfishMySQL.loadFeatures(SpearfishMySQL.java:709)
        at SpearfishMySQL$1.zoomChanged(SpearfishMySQL.java:457)
        at 
org.geotools.gui.swing.ZoomPane.fireZoomChanged0(ZoomPane.java:1387)
        at 
org.geotools.gui.swing.ZoomPane.fireZoomChanged(ZoomPane.java:1360)
        at org.geotools.gui.swing.ZoomPane.transform(ZoomPane.java:1167)
        at org.geotools.gui.swing.ZoomPane.transform(ZoomPane.java:1313)
        at org.geotools.gui.swing.ZoomPane.access$600(ZoomPane.java:212)
        at 
org.geotools.gui.swing.ZoomPane$3.actionPerformed(ZoomPane.java:734)
        at javax.swing.SwingUtilities.notifyAction(Unknown Source)
        at javax.swing.JComponent.processKeyBinding(Unknown Source)
        at javax.swing.JComponent.processKeyBindings(Unknown Source)
        at javax.swing.JComponent.processKeyEvent(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.KeyboardFocusManager.redispatchEvent(Unknown Source)
        at java.awt.DefaultKeyboardFocusManager.dispatchKeyEvent(Unknown 
Source)
......

It has no probelm if I dont remove the layers but add the updated layers 
into the MapContext directly. But this approach will increase the using 
memory as the times to add the layers to the MapContext increases, and the 
program will be very slow in the end. Can anyone give some hints ?

Regards

zekeng

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