ActivityNotFoundException?

问题:

I am getting an ActivityNotFoundException in the following code:

Main.java

Intent intent = new Intent();
     intent.setAction("com.test.app.TEST");
     startActivity(intent); // ActivityNotFoundException

Manifest.xml

<activity android:name=".MainActivity" android:theme="@android:style/Theme.Dialog">
        <intent-filter>
            <action android:name="com.test.app.TEST" />
        </intent-filter>
</activity>

回答1:

I've had this issue too, as perfectly concisely described by jpahn.

the period at the front did not give any help to me.

even with exactly this (a copy of the original question including edits), I would still get ActivityNotFoundException.

Main.java

Intent intent = new Intent();
 intent.setAction("com.test.app.TEST");
 startActivity(intent); // ActivityNotFoundException

Manifest.xml

<activity android:name=".MainActivity" android:theme="@android:style/Theme.Dialog">
    <intent-filter>
        <action android:name="com.test.app.TEST" />
    </intent-filter>
</activity>

This was resolved, after much trial-and-error, by simply adding this to the intent-filter in the manifest:

<category android:name="android.intent.category.DEFAULT" />

So the final manifest file contained:

<activity android:name=".MainActivity" android:theme="@android:style/Theme.Dialog">
    <intent-filter>
        <action android:name="com.test.app.TEST" />
        <category android:name="android.intent.category.DEFAULT" />
    </intent-filter>
</activity>

回答2:

Be sure to declare your activity in the manifest.xml within the aplication:

<application>
    <activity android:name=".YourNewActivity"/>
</application>

To start the new Activity:

Intent intent = new Intent(main.this, YourNewActivity.class);
startActivity(intent);

Where main stands for the current activity,

回答3:

I got this error after moving an activity class from one package to another. Clean build solved it (Project -> Clean).

回答4:

Add a . (dot) before your activity name in Android Manifest. So it should be android:name=".WordsToSpeakMainActivity"

回答5:

There two types of intents in android framework, 1-Implicit intents that you are using,

<activity android:name=".MainActivity" android:theme="@android:style/Theme.Dialog">
    <intent-filter>
        <action android:name="com.test.app.TEST" />
    </intent-filter>
</activity>

just add one line in intent filter

<intent-filter>
        <action android:name="com.test.app.TEST" />
        <category android:name="android.intent.category.DEFAULT" />
    </intent-filter>

2- Explicit Intents

Intent i=new Intent(CurrentActivity.this,WhereWeWantToGoActivity.class);

startActivity(i);

回答6:

To be safe you can also call your new activity like this:

Intent intent = new Intent();
intent.setClass(this, THECLASSNAME);
startActivity(intent); // 

However, you must add the activity to the androidmanifest - and write a . in front of it, e.g.

<activity android:name=".YOURACTIVITYNAME"></activity>

回答7:

I have some addition to the @Tom Pace answer. The answer is completely right, but to make it more clear:

ActivityNotFoundException occurs because of absence of

<category android:name="android.intent.category.DEFAULT" />

Because when Android OS see this in the manifest file, understands that this activity can receive intent.

The point ActivityNotFoundException thrown is that, when activity(intent-creator-activity) tries to create intent for other activity(intent-receiver-activity), Android OS sees there is intent for receiver activity but receiver activity does not receive anyone. Then Android OS returns null or empty intent to intent-creator-activity. And startActivity throws that exception.

I have found a code from android developers to avoid this exception:

// Verify the original intent will resolve to at least one activity
if (sendIntent.resolveActivity(getPackageManager()) != null) {
    startActivity(chooser);
}

Android Developers: Intent Filters

回答8:

To launch an activity by a string definition, use:

Intent intent = new Intent();
intent.setComponent(
        new ComponentName("com.app", "com.app.activity.TheActivity"));
startActivity(intent);

回答9:

At the very top of your AndroidManifest.xml, you'll see the package attribute

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.android.example"

and then, in the activity tag, you'll see the name attribute:

<activity
            android:name=".Something"

Make sure that the package name and activity name, when joined together, make the full package specification of your Activity i.e.

com.android.example + .Something = com.android.example.Something

Otherwise, you'll get a ActivityNotFoundException.

回答10:

I found a solution to this problem... I´m using 2 modules in a android studio project, the thing here is that I needed to add the activity to the main manifest file

<activity android:name="com.HeadApp.ARTry.UnityPlayerActivity"
          android:clearTaskOnLaunch="false" android:label="@string/app_name"
          android:screenOrientation="portrait" 
          android:configChanges="fontScale|keyboard|keyboardHidden|locale|mnc|mcc|navigation|orientation|screenLayout|screenSize|smallestScreenSize|uiMode|touchscreen"
/>

I had that in the unity activity manifest, I just copied the activity and paste it in the main manifest and that was it, hope it helps, eve been struggling a lot with this for the past 3 weeks