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PONewbie Android NullPointerException Trouble Shooting
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  1. PONewbie Android NullPointerException Trouble Shooting
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    copied!<p>I am having a similar problem as the person here: <a href="https://stackoverflow.com/questions/7977126/android-activity-error">Android activity error</a> I've read through the post. I also read through other posts. But I can't seem to get my Android application running. </p> <p>Description: I have one button. I want this button to work. I keep getting an NPE because of an OnClickListener. This is virtually an identical problem as the above post, but mine is behaving a little differently. Please help me. Thank you very much. </p> <p>Main.java</p> <pre><code>import android.app.Activity; import android.content.Intent; import android.os.Bundle; import android.view.View; import android.view.View.OnClickListener; import android.widget.Button; public class Main extends Activity { /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); Button b = (Button) findViewById(R.id.button1); b.setOnClickListener(new OnClickListener() { public void onClick(View v) { startActivity(new Intent(Main.this, Second.class)); } }); } } </code></pre> <p>Second.java</p> <pre><code>import android.app.Activity; import android.os.Bundle; public class Second extends Activity { @Override protected void onCreate(Bundle savedInstanceState) { // TODO Auto-generated method stub super.onCreate(savedInstanceState); } } </code></pre> <p>Error Message</p> <pre><code>12-27 09:19:10.729: W/dalvikvm(923): threadid=1: thread exiting with uncaught exception (group=0x409951f8) 12-27 09:19:10.749: E/AndroidRuntime(923): FATAL EXCEPTION: main 12-27 09:19:10.749: E/AndroidRuntime(923): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.harryoh.firstapp/com.harryoh.firstapp.Main}: java.lang.NullPointerException 12-27 09:19:10.749: E/AndroidRuntime(923): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1955) 12-27 09:19:10.749: E/AndroidRuntime(923): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1980) 12-27 09:19:10.749: E/AndroidRuntime(923): at android.app.ActivityThread.access$600(ActivityThread.java:122) 12-27 09:19:10.749: E/AndroidRuntime(923): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1146) 12-27 09:19:10.749: E/AndroidRuntime(923): at android.os.Handler.dispatchMessage(Handler.java:99) 12-27 09:19:10.749: E/AndroidRuntime(923): at android.os.Looper.loop(Looper.java:137) 12-27 09:19:10.749: E/AndroidRuntime(923): at android.app.ActivityThread.main(ActivityThread.java:4340) 12-27 09:19:10.749: E/AndroidRuntime(923): at java.lang.reflect.Method.invokeNative(Native Method) 12-27 09:19:10.749: E/AndroidRuntime(923): at java.lang.reflect.Method.invoke(Method.java:511) 12-27 09:19:10.749: E/AndroidRuntime(923): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784) 12-27 09:19:10.749: E/AndroidRuntime(923): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551) 12-27 09:19:10.749: E/AndroidRuntime(923): at dalvik.system.NativeStart.main(Native Method) 12-27 09:19:10.749: E/AndroidRuntime(923): Caused by: java.lang.NullPointerException 12-27 09:19:10.749: E/AndroidRuntime(923): at com.harryoh.firstapp.Main.onCreate(Main.java:19) 12-27 09:19:10.749: E/AndroidRuntime(923): at android.app.Activity.performCreate(Activity.java:4465) 12-27 09:19:10.749: E/AndroidRuntime(923): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049) 12-27 09:19:10.749: E/AndroidRuntime(923): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1919) 12-27 09:19:10.749: E/AndroidRuntime(923): ... 11 more </code></pre> <p>I really appreciate your help. I really want to learn Android, and these trouble shooting problems have always caused a lot of pain. </p> <p>EDIT: Thanks for your help. I will return the favor to this community once I am able... I haven't gone through your inputs yet, since I wanted to provide this as requested. I will work on it now. I hope it works. </p> <p>main.xml</p> <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt; &lt;LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="fill_parent" android:layout_height="fill_parent" android:orientation="vertical" &gt; &lt;TextView android:layout_width="fill_parent" android:layout_height="wrap_content" android:text="@string/hello" /&gt; &lt;/LinearLayout&gt; </code></pre>
 

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