android - Unable to start activity ComponentInfo{..} : java.lang.NullPointerException -
i'm trying start new activity when button playlistbtn clicked, , i'm getting nullpointerexception, can't see did go wrong references.
complete error log:
04-08 17:02:07.847: e/androidruntime(5869): fatal exception: main 04-08 17:02:07.847: e/androidruntime(5869): java.lang.runtimeexception: unable start activity componentinfo{app.and.androidmusic/app.and.androidmusic.playlistactivity}: java.lang.nullpointerexception 04-08 17:02:07.847: e/androidruntime(5869): @ android.app.activitythread.performlaunchactivity(activitythread.java:2180) 04-08 17:02:07.847: e/androidruntime(5869): @ android.app.activitythread.handlelaunchactivity(activitythread.java:2230) 04-08 17:02:07.847: e/androidruntime(5869): @ android.app.activitythread.access$600(activitythread.java:141) 04-08 17:02:07.847: e/androidruntime(5869): @ android.app.activitythread$h.handlemessage(activitythread.java:1234) 04-08 17:02:07.847: e/androidruntime(5869): @ android.os.handler.dispatchmessage(handler.java:99) 04-08 17:02:07.847: e/androidruntime(5869): @ android.os.looper.loop(looper.java:137) 04-08 17:02:07.847: e/androidruntime(5869): @ android.app.activitythread.main(activitythread.java:5039) 04-08 17:02:07.847: e/androidruntime(5869): @ java.lang.reflect.method.invokenative(native method) 04-08 17:02:07.847: e/androidruntime(5869): @ java.lang.reflect.method.invoke(method.java:511) 04-08 17:02:07.847: e/androidruntime(5869): @ com.android.internal.os.zygoteinit$methodandargscaller.run(zygoteinit.java:793) 04-08 17:02:07.847: e/androidruntime(5869): @ com.android.internal.os.zygoteinit.main(zygoteinit.java:560) 04-08 17:02:07.847: e/androidruntime(5869): @ dalvik.system.nativestart.main(native method) 04-08 17:02:07.847: e/androidruntime(5869): caused by: java.lang.nullpointerexception 04-08 17:02:07.847: e/androidruntime(5869): @ app.and.androidmusic.playlistactivity.oncreate(playlistactivity.java:68) 04-08 17:02:07.847: e/androidruntime(5869): @ android.app.activity.performcreate(activity.java:5104) 04-08 17:02:07.847: e/androidruntime(5869): @ android.app.instrumentation.callactivityoncreate(instrumentation.java:1080) 04-08 17:02:07.847: e/androidruntime(5869): @ android.app.activitythread.performlaunchactivity(activitythread.java:2144) mainactivity.java:
public class mainactivity extends listactivity { ... protected void oncreate(bundle savedinstancestate) { super.oncreate(savedinstancestate); setcontentview(r.layout.activity_main); ... button btnplaylist = (button) findviewbyid(r.id.playlistbtn); btnplaylist.setonclicklistener(new view.onclicklistener() { @override public void onclick(view arg0) { intent in = new intent(getapplicationcontext(), playlistactivity.class); startactivity(in); playlistactivity.java:
public class playlistactivity extends listactivity{ ... @override protected void oncreate(bundle savedinstancestate) { super.oncreate(savedinstancestate); setcontentview(r.layout.activity_playlist); { androidmanifest.xml:
<activity android:name="app.and.androidmusic.mainactivity" android:label="@string/app_name" > <intent-filter> <action android:name="android.intent.action.main" /> <category android:name="android.intent.category.launcher" /> </intent-filter> </activity> <activity android:name=".playlistactivity" /> ok, here activity_main.xml asked it's quite long:
<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" tools:context=".mainactivity" > <app.and.androidmusic.dragndroplistview android:id="@+id/android:list" android:layout_width="match_parent" android:layout_height="300dp" android:layout_below="@+id/playlistbtn" android:layout_alignparentleft="true" > </app.and.androidmusic.dragndroplistview> <button android:id="@+id/playbtn" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_below="@id/android:list" android:layout_torightof="@+id/prevbtn" android:text="@string/playbtn" /> <button android:id="@+id/pausebtn" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_below="@id/android:list" android:layout_torightof="@+id/playbtn" android:text="@string/pausebtn" /> <button android:id="@+id/prevbtn" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_below="@id/android:list" android:text="@string/prevbtn" /> <button android:id="@+id/nextbtn" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_below="@id/android:list" android:layout_torightof="@+id/pausebtn" android:text="@string/nextbtn" /> <button android:id="@+id/songsbtn" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_below="@+id/songtxt" android:text="@string/songsbtn" /> <button android:id="@+id/playlistbtn" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_below="@+id/songtxt" android:layout_torightof="@+id/songsbtn" android:text="@string/playlistbtn" /> <button android:id="@+id/eqbtn" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_below="@+id/songtxt" android:layout_torightof="@+id/playlistbtn" android:text="@string/eqbtn" /> <textview android:id="@+id/songtxt" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignparenttop="true" android:layout_centerhorizontal="true" android:text="" /> </relativelayout>
wild guess:
btnplaylist null , there's no button id playlistbtn in activity_main.xml.
edit:
the problem inside playlistactivity (line 68). whatever object you're accessing there null.
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