Question

I am not totally new to working with the eclipse android plugin but I am new at writing a project from the ground up. So I went to the Android developers website to follow the ‘Hello World’ tutorial.

When I run my program the emulator puts up a screen that says
unfortunately Hello, Android Has stopped working.
my code is:

HelloAndroid.Java

package daniel.android.projects;

import android.app.Activity;
import android.os.Bundle;

    public class HelloAndroid extends Activity {
        /** Called when the activity is first created. */
        @Override
        public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            Object o = null;
            o.toString();
            setContentView(R.layout.main);
        }
    }

Main.xml

<?xml version="1.0" encoding="utf-8"?>
<TextView xmlns:android="http://schemas.android.com/apk/res/android"
  android:id="@+id/textview"
  android:layout_width="fill_parent"
  android:layout_height="fill_parent"
  android:text="@string/hello"/>

Strings.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <string name="hello">Hello, Android! I am a string resource!</string>
    <string name="app_name">Hello, Android</string>
</resources>

Manifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="daniel.android.projects"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk android:minSdkVersion="15" />

    <application
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name" >
        <activity
            android:name=".AndroidTesterActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

Answer 1

You have a null pointer exception, you assign null to o and then call toString() on it:

Object o = null;
o.toString();

It seems like it serves nothing in your application anyway, it shouldn’t be there.

Also, looking at your code, you create HelloAndroid class, but in themanifest you declare

android:name=".AndroidTesterActivity"

it should be

android:name=".HelloAndroid"