android - when slide fragment with gridview, it happens java.lang.NullPointerException -
i'm trying implement avtivity use viewpager fragment gridview in android. every gridview contains 8 apps icon of system , number of fragment dynamic. works slide third fragment. sorry english.
in current state of app, following exception:
v/test_gridadapter( 1418): position 0, com.android.providers.downloads.ui getview v/test_gridadapter( 1418): position 0, com.android.providers.downloads.ui getview v/test_gridadapter( 1418): position 0, com.android.providers.downloads.ui getview v/test_gridadapter( 1418): position 0, com.android.providers.downloads.ui getview v/test_gridadapter( 1418): position 0, com.android.providers.downloads.ui getview v/test_gridadapter( 1418): position 1, com.android.quicksearchbox getview v/test_gridadapter( 1418): position 2, com.rockchip.gamecontrolsetting getview v/test_gridadapter( 1418): position 3, com.android.apkinstaller getview v/test_gridadapter( 1418): position 4, com.android.rockchip getview v/test_gridadapter( 1418): position 5, com.android.speechrecorder getview v/test_gridadapter( 1418): position 6, com.android.videoeditor getview v/test_gridadapter( 1418): position 7, com.rockchip.wfd getview v/test_gridadapter( 1418): position 0, com.rockchip.mediacenter getview v/test_gridadapter( 1418): position 0, com.rockchip.mediacenter getview v/test_gridadapter( 1418): position 0, com.rockchip.mediacenter getview v/test_gridadapter( 1418): position 0, com.rockchip.mediacenter getview v/test_gridadapter( 1418): position 0, com.rockchip.mediacenter getview d/androidruntime( 1418): shutting down vm w/dalvikvm( 1418): threadid=1: thread exiting uncaught exception (group=0x41c79300) e/androidruntime( 1418): fatal exception: main e/androidruntime( 1418): process: com.example.zhengjy.ljlauncher, pid: 1418 e/androidruntime( 1418): java.lang.nullpointerexception e/androidruntime( 1418): @ com.example.zhengjy.ljlauncher.gridadapter.getview(gridadapter.java:95) e/androidruntime( 1418): @ android.widget.abslistview.obtainview(abslistview.java:2263) e/androidruntime( 1418): @ android.widget.gridview.makeandaddview(gridview.java:1345) e/androidruntime( 1418): @ android.widget.gridview.makerow(gridview.java:345) e/androidruntime( 1418): @ android.widget.gridview.filldown(gridview.java:287) e/androidruntime( 1418): @ android.widget.gridview.fillfromtop(gridview.java:421) e/androidruntime( 1418): @ android.widget.gridview.layoutchildren(gridview.java:1233) e/androidruntime( 1418): @ android.widget.abslistview.onlayout(abslistview.java:2091) e/androidruntime( 1418): @ android.view.view.layout(view.java:14838) e/androidruntime( 1418): @ android.view.viewgroup.layout(viewgroup.java:4631) e/androidruntime( 1418): @ android.widget.linearlayout.setchildframe(linearlayout.java:1671) e/androidruntime( 1418): @ android.widget.linearlayout.layoutvertical(linearlayout.java:1525) e/androidruntime( 1418): @ android.widget.linearlayout.onlayout(linearlayout.java:1434) e/androidruntime( 1418): @ android.view.view.layout(view.java:14838) e/androidruntime( 1418): @ android.view.viewgroup.layout(viewgroup.java:4631) e/androidruntime( 1418): @ android.support.v4.view.viewpager.onlayout(viewpager.java:1626) e/androidruntime( 1418): @ android.view.view.layout(view.java:14838) e/androidruntime( 1418): @ android.view.viewgroup.layout(viewgroup.java:4631) e/androidruntime( 1418): @ android.widget.linearlayout.setchildframe(linearlayout.java:1671) e/androidruntime( 1418): @ android.widget.linearlayout.layoutvertical(linearlayout.java:1525) e/androidruntime( 1418): @ android.widget.linearlayout.onlayout(linearlayout.java:1434) e/androidruntime( 1418): @ android.view.view.layout(view.java:14838) e/androidruntime( 1418): @ android.view.viewgroup.layout(viewgroup.java:4631) e/androidruntime( 1418): @ android.widget.framelayout.layoutchildren(framelayout.java:453) e/androidruntime( 1418): @ android.widget.framelayout.onlayout(framelayout.java:388) e/androidruntime( 1418): @ android.view.view.layout(view.java:14838) e/androidruntime( 1418): @ android.view.viewgroup.layout(viewgroup.java:4631) e/androidruntime( 1418): @ android.widget.relativelayout.onlayout(relativelayout.java:1055) e/androidruntime( 1418): @ android.view.view.layout(view.java:14838) e/androidruntime( 1418): @ android.view.viewgroup.layout(viewgroup.java:4631) e/androidruntime( 1418): @ android.widget.framelayout.layoutchildren(framelayout.java:453) e/androidruntime( 1418): @ android.widget.framelayout.onlayout(framelayout.java:388) e/androidruntime( 1418): @ android.view.view.layout(view.java:14838) e/androidruntime( 1418): @ android.view.viewgroup.layout(viewgroup.java:4631) e/androidruntime( 1418): @ android.widget.linearlayout.setchildframe(linearlayout.java:1671) e/androidruntime( 1418): @ android.widget.linearlayout.layoutvertical(linearlayout.java:1525) e/androidruntime( 1418): @ android.widget.linearlayout.onlayout(linearlayout.java:1434) e/androidruntime( 1418): @ android.view.view.layout(view.java:14838) e/androidruntime( 1418): @ android.view.viewgroup.layout(viewgroup.java:4631) e/androidruntime( 1418): @ android.widget.framelayout.layoutchildren(framelayout.java:453) e/androidruntime( 1418): @ android.widget.framelayout.onlayout(framelayout.java:388) e/androidruntime( 1418): @ android.view.view.layout(view.java:14838) e/androidruntime( 1418): @ android.view.viewgroup.layout(viewgroup.java:4631) e/androidruntime( 1418): @ android.view.viewrootimpl.performlayout(viewrootimpl.java:1996) e/androidruntime( 1418): @ android.view.viewrootimpl.performtraversals(viewrootimpl.java:1753) e/androidruntime( 1418): @ android.view.viewrootimpl.dotraversal(viewrootimpl.java:1005) e/androidruntime( 1418): @ android.view.viewrootimpl$traversalrunnable.run(viewrootimpl.java:5750) e/androidruntime( 1418): @ android.view.choreographer$callbackrecord.run(choreographer.java:761) e/androidruntime( 1418): @ android.view.choreographer.docallbacks(choreographer.java:574) e/androidruntime( 1418): @ android.view.choreographer.doframe(choreographer.java:544) e/androidruntime( 1418): @ android.view.choreographer$framedisplayeventreceiver.run(choreographer.java:747) e/androidruntime( 1418): @ android.os.handler.handlecallback(handler.java:733) e/androidruntime( 1418): @ android.os.handler.dispatchmessage(handler.java:95) e/androidruntime( 1418): @ android.os.looper.loop(looper.java:136) e/androidruntime( 1418): @ android.app.activitythread.main(activitythread.java:5017) e/androidruntime( 1418): @ java.lang.reflect.method.invokenative(native method) e/androidruntime( 1418): @ java.lang.reflect.method.invoke(method.java:515) e/androidruntime( 1418): @ com.android.internal.os.zygoteinit$methodandargscaller.run(zygoteinit.java:794) e/androidruntime( 1418): @ com.android.internal.os.zygoteinit.main(zygoteinit.java:610) e/androidruntime( 1418): @ dalvik.system.nativestart.main(native method) the activiy xml :
<android.support.v4.view.viewpager android:id="@+id/pager" android:layout_width="match_parent" android:layout_height="match_parent" android:layout_marginbottom="1dp" android:layout_weight="1" /> <com.viewpagerindicator.circlepageindicator android:id="@+id/pagerindicator" android:layout_width="match_parent" android:layout_height="match_parent" android:padding="3dp" android:layout_gravity="bottom|center_horizontal" android:layout_marginbottom="5dp" android:layout_weight="5" /> the grid.xml is:
<linearlayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="fill_parent" android:layout_height="wrap_content" android:orientation="vertical" > <gridview android:id="@+id/gridview" android:layout_width="fill_parent" android:layout_height="fill_parent" android:layout_margin="10dp" android:layout_margintop="10dp" android:horizontalspacing="100dp" android:listselector="@android:color/transparent" android:numcolumns="4" android:stretchmode="columnwidth" android:verticalspacing="2dp" />
the grid_item xml is:
<relativelayout xmlns:android="http://schemas.android.com/apk/res/android" android:id="@+id/app_grid_item" android:layout_width="wrap_content" android:layout_height="match_parent" android:padding="@dimen/app_margin"> <imageview android:id="@+id/app_icon" android:layout_width="@dimen/grid_icon_width" android:layout_height="@dimen/grid_icon_height" android:layout_centerhorizontal="true" android:visibility="visible" /> <relativelayout android:id="@+id/label_container" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_below="@+id/app_icon" android:layout_alignparentbottom="true"> <textview android:id="@+id/app_name" android:layout_width="match_parent" android:layout_height="wrap_content" android:gravity="center_horizontal" android:minwidth="20dp" android:ellipsize="end" android:singleline="true" android:padding="4dp" android:textsize="15sp" /> </relativelayout> the gridadapter is:
public class gridadapter extends baseadapter { context context; private griditems[] items; private layoutinflater minflater; public class viewholder { public imageview imageview; public textview texttitle; } public gridadapter(context context, griditems[] items) { minflater = (layoutinflater) context .getsystemservice(context.layout_inflater_service); this.context = context; this.items = items; } ... @override public void notifydatasetchanged() { super.notifydatasetchanged(); } @override public object getitem(int position) { if (items != null && position >= 0 && position < getcount()) { return items[position]; } return null; } @override public long getitemid(int position) { if (items != null && position >= 0 && position < getcount()) { return items[position].id; } return 0; } public void setitemslist(griditems[] locations) { this.items = locations; } @override public view getview(int position, view convertview, viewgroup parent) { viewholder viewholder; if (convertview == null) { convertview = minflater.inflate(r.layout.app_grid_item, parent, false); viewholder = new viewholder(); viewholder.imageview = ((imageview) convertview.findviewbyid(r.id.app_icon)); viewholder.texttitle = ((textview) convertview.findviewbyid(r.id.app_name)); convertview.settag(viewholder); } else { viewholder = (viewholder) convertview.gettag(); } griditems griditems = items[position]; viewholder.imageview.setimagedrawable(griditems.appinfo.icon); viewholder.texttitle.settext(griditems.appinfo.name); log.v(tag, "the position " + position + ", " + griditems.appinfo.packagename + " getview"); return convertview; } }
the fragmentstatepageradapter :
private class mypageradapter extends fragmentstatepageradapter { private list<gridfragment> fragments; fragmentmanager fm; public mypageradapter(fragmentmanager fm, list<gridfragment> gridfragments) { super(fm); this.fm = fm; this.fragments = gridfragments; } @override public gridfragment getitem(int position) { return this.fragments.get(position); } @override public int getcount() { return this.fragments.size(); } } }
the null pointer seems in getview() method. determine item null following:
public view getview(int position, view convertview, viewgroup parent) { viewholder viewholder; if (convertview == null) { convertview = minflater.inflate(r.layout.app_grid_item, parent, false); viewholder = new viewholder(); viewholder.imageview = ((imageview) convertview.findviewbyid(r.id.app_icon)); viewholder.texttitle = ((textview) convertview.findviewbyid(r.id.app_name)); convertview.settag(viewholder); } else { viewholder = (viewholder) convertview.gettag(); } if (viewholder == null) { log.e("gridadapter", "viewholder null") return convertview; } griditems griditems = items[position]; if (griditems == null || griditems.appinfo == null) { log.e("gridadapter", "griditems or appinfo null") return convertview; } viewholder.imageview.setimagedrawable(griditems.appinfo.icon); viewholder.texttitle.settext(griditems.appinfo.name); log.v(tag, "the position " + position + ", " + griditems.appinfo.packagename + " getview"); return convertview; }
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