After picking up my projects after a month, I run into a really catastrophic problem: I cannot start new activities anymore! Everytime I use an intent to do that, I get an Activity not found error and Android studio wants me to declare my activities in the manifest. However, I have checked the declarations for what feels like years now and have no idea where the problem is. I have created a (several, rather) new project(s) from scratch to avoid any complications and the problem persists. Among other things, I have tried declaring the activities like this

```
      android:name=".MainActivity"

```

and like this

```
      android:name="com.example.dorothea.intenttest.MainActivity"

```

and formulating the intent like this

```
     public final Intent intenttest = new Intent(this, SecondActivity.class);

```

and this

```
     public final Intent intenttest = new Intent(MainActivity.this, SecondActivity.class);

```

Also, because this problem persists in even the simplest of projects, I cannot think of a null pointer exception in the construction of the started activity that has escaped me. I am really stumped here and any help would be very appreciated. Probably it is a really dumb error on my part, but I cannot see which one :(
In the following, I attach the logcat and code of a very simple (two blank pages) app that I used to find the problem. I let Android Studio create two blank activities and just added two lines of code to the Java file of the first.

Logcat:

```
 08-24 13:36:32.460  26726-26726/? E/AndroidRuntime﹕ FATAL EXCEPTION:      main
     java.lang.RuntimeException: Unable to start activity      ComponentInfo{com.example.dorothea.intenttest/com.example.dorothea.intenttest     .MainActivity}: android.content.ActivityNotFoundException: Unable to find explicit activity class {/com.example.dorothea.intenttest.SecondActivity}; have you declared this activity in your AndroidManifest.xml?
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2252)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2306)
        at android.app.ActivityThread.access$700(ActivityThread.java:153)
 at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1286)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:176)
        at android.app.ActivityThread.main(ActivityThread.java:5302)
        at java.lang.reflect.Method.invokeNative(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:511)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1102)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:869)
        at dalvik.system.NativeStart.main(Native Method)
 Caused by: android.content.ActivityNotFoundException: Unable to find explicit activity class {/com.example.dorothea.intenttest.SecondActivity}; have you declared this activity in your AndroidManifest.xml?
        at android.app.Instrumentation.checkStartActivityResult(Instrumentation.java:1635)
        at android.app.Instrumentation.execStartActivity(Instrumentation.java:1434)
        at android.app.Activity.startActivityForResult(Activity.java:3434)
        at android.app.Activity.startActivityForResult(Activity.java:3395)
        at android.support.v4.app.FragmentActivity.startActivityForResult(FragmentActivity.java:820)
        at android.app.Activity.startActivity(Activity.java:3630)
        at android.app.Activity.startActivity(Activity.java:3598)
        at com.example.dorothea.intenttest.MainActivity.onCreate(MainActivity.java:16)
        at android.app.Activity.performCreate(Activity.java:5326)
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1097)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2215)
     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2306)
   at android.app.ActivityThread.access$700(ActivityThread.java:153)
 at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1286)
 at android.os.Handler.dispatchMessage(Handler.java:99)
             at android.os.Looper.loop(Looper.java:176)
             at android.app.ActivityThread.main(ActivityThread.java:5302)
             at java.lang.reflect.Method.invokeNative(Native Method)
             at java.lang.reflect.Method.invoke(Method.java:511)
             at  com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1102)
             at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:869)
             at dalvik.system.NativeStart.main(Native Method)
      08-24 13:36:39.137  26726-26726/? I/Process﹕ Sending signal. PID: 26726 SIG: 9

```

Java file first activity:

```
package com.example.dorothea.intenttest;

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;

public class MainActivity extends AppCompatActivity {
    public final Intent intenttest = new Intent(this, SecondActivity.class);

    @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_main);
         startActivity(intenttest);
     }

     @Override
    public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.menu_main, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();

    //noinspection SimplifiableIfStatement
    if (id == R.id.action_settings) {
        return true;
    }

    return super.onOptionsItemSelected(item);
}

```

}

The activity to be started is just like android created it:

```
 package com.example.dorothea.intenttest;

 import android.support.v7.app.AppCompatActivity;
 import android.os.Bundle;
 import android.view.Menu;
 import android.view.MenuItem;

 public class SecondActivity extends AppCompatActivity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_second);
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.menu_second, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();

    //noinspection SimplifiableIfStatement
    if (id == R.id.action_settings) {
        return true;
    }

    return super.onOptionsItemSelected(item);
}

```

}

And needless to say, Android Studio has in fact declared the activities in the manifest file, which is here:

```
  <?xml version="1.0" encoding="utf-8"?>
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
     package="com.example.dorothea.intenttest" >

<application
    android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:theme="@style/AppTheme" >
    <activity
        android:name=".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=".SecondActivity"
        android:label="@string/title_activity_second" >
    </activity>
</application>

```