android - Using an external xml file for custom list view adapter? -
i developing first android application. in app there should listview displaying @ left side pic , next 2 textviews.
the xml listview looks following:
<relativelayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="fill_parent" android:layout_height="?android:attr/listpreferreditemheight" android:padding="6dip" > <imageview android:id="@+id/icon" android:layout_width="wrap_content" android:layout_height="fill_parent" android:layout_alignparentbottom="true" android:layout_alignparenttop="true" android:layout_marginright="6dip" android:contentdescription="todo" android:src="@drawable/ic_launcher" /> <textview android:id="@+id/secondline" android:layout_width="fill_parent" android:layout_height="26dip" android:layout_alignparentbottom="true" android:layout_alignparentright="true" android:layout_torightof="@id/icon" android:ellipsize="marquee" android:singleline="true" android:text="description" android:textsize="12sp" /> <textview android:id="@+id/firstline" android:layout_width="fill_parent" android:layout_height="wrap_content" android:layout_above="@id/secondline" android:layout_alignparentright="true" android:layout_alignparenttop="true" android:layout_alignwithparentifmissing="true" android:layout_torightof="@id/icon" android:gravity="center_vertical" android:text="example application" android:textsize="16sp" /> </relativelayout> the xml the mainactivity looking this:
<relativelayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" android:paddingleft="@dimen/activity_horizontal_margin" android:paddingright="@dimen/activity_horizontal_margin" android:paddingtop="@dimen/activity_vertical_margin" android:paddingbottom="@dimen/activity_vertical_margin" tools:context=".mainactivity"> <listview xmlns:android="rowlayout" android:id="@+id/list" android:layout_width="wrap_content" android:layout_height="wrap_content" /> </relativelayout> my mainactivity.java code looks looks following:
import android.app.listactivity; import android.os.bundle; import android.view.view; import android.widget.listview; import android.widget.toast; public class mainactivity extends listactivity { public void oncreate(bundle icicle) { super.oncreate(icicle); string[] values = new string[] { "android", "iphone", "windowsmobile", "blackberry", "webos", "ubuntu", "windows7", "max os x", "linux", "os/2" }; string[] values2 = new string[] {"good","bad","medium","not yet tested","don't know it","very cool","just windows","piece of shit","very cool","don't know too"}; listview listview = (listview) findviewbyid(r.id.listview); listviewadapter adapter1 = new listviewadapter (values,values2,android.r.id.list); listview.setadapter(adapter1); } } my current custom adapter looks this:
import android.widget.baseadapter; import android.widget.textview; public class listviewadapter extends baseadapter { string[] values; string[] values2; context ctxt; layoutinflater layoutinflater; public listviewadapter (string [] values,string [] values2, context context) { values = values; values2 = values2; ctxt = context; layoutinflater = (layoutinflater) context.getsystemservice (context.layout_inflater_service); } @override public int getcount() { return values.length; } @override public object getitem(int position) { string [] res = new string [] {values [position],values2 [position]}; return res; } @override public long getitemid(int position) { return 0; } @override public view getview(int position, view convertview, viewgroup parent) { textview name1 = (textview)convertview.findviewbyid(android.r.id.text1); textview name2 = (textview)convertview.findviewbyid(android.r.id.text2); name1.settext(values [position]); name2.settext(values2 [position]); return convertview; } } i following error when launching app:
process: de.gotthold.myapplication2.app, pid: 16723 java.lang.runtimeexception: unable start activity componentinfo{de.gotthold.myapplication2.app/de.gotthold.myapplication2.app.mainactivity}: java.lang.nullpointerexception: attempt invoke virtual method 'void android.widget.listview.setadapter(android.widget.listadapter)' on null object reference @ android.app.activitythread.performlaunchactivity(activitythread.java:2411) @ android.app.activitythread.handlelaunchactivity(activitythread.java:2474) @ android.app.activitythread.access$800(activitythread.java:144) @ android.app.activitythread$h.handlemessage(activitythread.java:1359) @ android.os.handler.dispatchmessage(handler.java:102) @ android.os.looper.loop(looper.java:155) @ android.app.activitythread.main(activitythread.java:5727) @ java.lang.reflect.method.invoke(native method) @ java.lang.reflect.method.invoke(method.java:372) @ com.android.internal.os.zygoteinit$methodandargscaller.run(zygoteinit.java:1029) @ com.android.internal.os.zygoteinit.main(zygoteinit.java:824) caused by: java.lang.nullpointerexception: attempt invoke virtual method 'void android.widget.listview.setadapter(android.widget.listadapter)' on null object reference @ de.gotthold.myapplication2.app.mainactivity.oncreate(mainactivity.java:19) @ android.app.activity.performcreate(activity.java:5961) @ android.app.instrumentation.callactivityoncreate(instrumentation.java:1129) @ android.app.activitythread.performlaunchactivity(activitythread.java:2364) at android.app.activitythread.handlelaunchactivity(activitythread.java:2474) at android.app.activitythread.access$800(activitythread.java:144) at android.app.activitythread$h.handlemessage(activitythread.java:1359) at android.os.handler.dispatchmessage(handler.java:102) at android.os.looper.loop(looper.java:155) at android.app.activitythread.main(activitythread.java:5727) at java.lang.reflect.method.invoke(native method) at java.lang.reflect.method.invoke(method.java:372) at com.android.internal.os.zygoteinit$methodandargscaller.run(zygoteinit.java:1029) at com.android.internal.os.zygoteinit.main(zygoteinit.java:824) 02-06 12:45:27.641 16723-16723/? d/process﹕ killprocess, pid=16723 02-06 12:45:27.641 16723-16723/? d/process﹕ com.android.internal.os.runtimeinit$uncaughthandler.uncaughtexception:138 java.lang.threadgroup.uncaughtexception:693 java.lang.threadgroup.uncaughtexception:690
i explanation problem, not link tutorial because tried working trough them , happend. read multiple stackoverflow threads, none of solve problem.
thanks help, school-guy
p.s.: not app developing diffrent 1 messing around new learnt knowledge.
you have lot of errors in code. let me point them out
error 1
setting adapter. cannot call without setcontentview()
listview listview = (listview) findviewbyid(r.id.listview); listview.setadapter(adapter1); you should call
setlistadapter(adapter1); better way of doing is:
use acticity not listactivity. in oncreate()
setconetentview(r.id.your_main_view); listview listview = (listview) findviewbyid(r.id.listview); listviewadapter adapter1 = new listviewadapter (values,values2,this); listview.setadapter(adapter1); error 2
your listviewadapter constructor has parameters
(string[] values,string [], context) but sending
(values,values2,android.r.id.list) you should instead send
(values,values2,this) error 3
you not inflating view in adpater. without inflating listview.xml view cannot convert view type object, cannot create custom listview it
you should do
public static class holder //holder class containing view components/widgets { textview name1,name2; } @override public view getview(int position, view convertview, viewgroup parent) { holder holder=new holder(); view convertview=inflater.inflate(r.layout.row_list, null); holder.name1 = convertview.(textview)convertview.findviewbyid(r.id.text1); holder.name2 = convertview.(textview)convertview.findviewbyid(r.id.text2); holder.name1.settext(values [position]); holder.name2.settext(values2 [position]); return convertview; } for more detail understanding have written example here
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