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PONullPointerException when accessing the widget in Activity
 

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  1. PONullPointerException when accessing the widget in Activity
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    <p>My LogCat shows <code>NullPointerException</code>, no matter which code I run as the main activity. The same exception is occurring in all activities that I try in same or different projects.</p> <p><strong>MainActivity</strong></p> <pre><code>public class MainActivity extends Activity implements View.OnClickListener{ private static EditText et; private static Button b; private static TextView tv; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); et=(EditText)findViewById(R.id.editText1); Button b=(Button)findViewById(R.id.button1); TextView tv=(TextView)findViewById(R.id.textView1); b.setOnClickListener(this); setContentView(R.layout.activity_main); } @Override public void onClick(View v) { // TODO Auto-generated method stub tv.setText(et.getText()); } } </code></pre> <p><strong>activity_main.xml</strong></p> <pre><code>&lt;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:paddingBottom="@dimen/activity_vertical_margin" android:paddingLeft="@dimen/activity_horizontal_margin" android:paddingRight="@dimen/activity_horizontal_margin" android:paddingTop="@dimen/activity_vertical_margin" tools:context=".MainActivity" &gt; &lt;EditText android:id="@+id/editText1" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignParentTop="true" android:layout_centerHorizontal="true" android:layout_marginTop="73dp" android:ems="10" &gt; &lt;requestFocus /&gt; &lt;/EditText&gt; &lt;Button android:id="@+id/button1" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_below="@+id/editText1" android:layout_centerHorizontal="true" android:layout_marginTop="68dp" android:text="Button" /&gt; &lt;TextView android:id="@+id/textView1" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_below="@+id/button1" android:layout_centerHorizontal="true" android:layout_marginTop="72dp" android:text="TextView" /&gt; &lt;/RelativeLayout&gt; </code></pre> <p><strong>Manifest file</strong></p> <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt; &lt;manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.android.stuff" android:versionCode="1" android:versionName="1.0" &gt; &lt;uses-sdk android:minSdkVersion="8" android:targetSdkVersion="15" /&gt; &lt;application android:allowBackup="true" android:icon="@drawable/ic_launcher" android:label="@string/app_name" android:theme="@style/AppTheme" &gt; &lt;activity android:name="com.android.stuff.MainActivity" android:label="@string/app_name" &gt; &lt;intent-filter&gt; &lt;action android:name="android.intent.action.MAIN" /&gt; &lt;category android:name="android.intent.category.LAUNCHER" /&gt; &lt;/intent-filter&gt; &lt;/activity&gt; &lt;/application&gt; &lt;/manifest&gt; </code></pre> <p><strong>LogCat</strong></p> <pre><code>10-09 05:52:58.953: E/Trace(667): error opening trace file: No such file or directory (2) 10-09 05:53:00.152: D/AndroidRuntime(667): Shutting down VM 10-09 05:53:00.172: W/dalvikvm(667): threadid=1: thread exiting with uncaught exception (group=0x40a13300) 10-09 05:53:00.202: E/AndroidRuntime(667): FATAL EXCEPTION: main 10-09 05:53:00.202: E/AndroidRuntime(667): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.android.stuff/com.android.stuff.MainActivity}: java.lang.NullPointerException 10-09 05:53:00.202: E/AndroidRuntime(667): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2059) 10-09 05:53:00.202: E/AndroidRuntime(667): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2084) 10-09 05:53:00.202: E/AndroidRuntime(667): at android.app.ActivityThread.access$600(ActivityThread.java:130) 10-09 05:53:00.202: E/AndroidRuntime(667): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1195) 10-09 05:53:00.202: E/AndroidRuntime(667): at android.os.Handler.dispatchMessage(Handler.java:99) 10-09 05:53:00.202: E/AndroidRuntime(667): at android.os.Looper.loop(Looper.java:137) 10-09 05:53:00.202: E/AndroidRuntime(667): at android.app.ActivityThread.main(ActivityThread.java:4745) 10-09 05:53:00.202: E/AndroidRuntime(667): at java.lang.reflect.Method.invokeNative(Native Method) 10-09 05:53:00.202: E/AndroidRuntime(667): at java.lang.reflect.Method.invoke(Method.java:511) 10-09 05:53:00.202: E/AndroidRuntime(667): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786) 10-09 05:53:00.202: E/AndroidRuntime(667): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553) 10-09 05:53:00.202: E/AndroidRuntime(667): at dalvik.system.NativeStart.main(Native Method) 10-09 05:53:00.202: E/AndroidRuntime(667): Caused by: java.lang.NullPointerException 10-09 05:53:00.202: E/AndroidRuntime(667): at com.android.stuff.MainActivity.onCreate(MainActivity.java:23) 10-09 05:53:00.202: E/AndroidRuntime(667): at android.app.Activity.performCreate(Activity.java:5008) 10-09 05:53:00.202: E/AndroidRuntime(667): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1079) 10-09 05:53:00.202: E/AndroidRuntime(667): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2023) 10-09 05:53:00.202: E/AndroidRuntime(667): ... 11 more 10-09 05:53:03.652: I/Process(667): Sending signal. PID: 667 SIG: 9 </code></pre>
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    1. COPut setContentView(R.layout.activity_main); right after super.onCreate(savedInstanceState);
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    2. COAnd please validate an answer in order to thank the people who took time to answer your question. Thanks in advance for that.
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