Hey there! Let me walk you through this step by step—since you're new to Android Studio, figuring out manifest declarations can feel a bit overwhelming at first, but it's really simple once you know the basics.

First, the Basic Structure of an Activity Declaration #

Every activity in your app needs to be registered inside the <application> tag of your AndroidManifest.xml file. Here's the core template:

<activity
    android:name="YOUR_ACTIVITY_CLASS_NAME"
    android:label="YOUR_DISPLAY_LABEL">
    <!-- Optional: Add intent filters if this is a launchable activity -->
</activity>

Let's Break Down the name Parameter #

This is the most critical part—it tells Android exactly which Java/Kotlin class corresponds to this activity. You have two valid ways to write it:

• Relative Package Name: If your activity class is in the same base package as declared at the top of your AndroidManifest.xml (look for the package="com.yourdomain.yourapp" line), you can use a dot followed by the class name. For example, if your activity is named MainActivity and your base package is com.example.myapp, write android:name=".MainActivity".
• Full Qualified Class Name: If your activity is in a subpackage (like com.example.myapp.ui.home), you need to write the full path: android:name="com.example.myapp.ui.home.HomeActivity".

How to Get the Exact Class Name? #

• Open your Activity class file (like MainActivity.kt or MainActivity.java). At the very top, you'll see the package line (e.g., package com.example.myapp;). Combine that with the class name (the word after class or public class) to get the full path.
• Alternatively, right-click your Activity class in the Project view → Copy Reference—this will copy the full qualified name directly to your clipboard, which you can paste straight into the name parameter.

Understanding the label Parameter #

This controls the text that shows up for your activity in places like:

• The app launcher (if this is your main activity)
• The action bar/toolbar of the activity
• The recent apps list

You have two options here too:

• Hardcoded Text: Just write a string directly, like android:label="My Home Page". This is quick, but not recommended for apps you plan to localize (translate to other languages).
• String Resource: Use a reference to a string in your res/values/strings.xml file, like android:label="@string/home_activity_label". This is the best practice because you can easily add translations for different languages later without changing the manifest.

Full Example #

Here's a complete manifest snippet to tie it all together:

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

    <application
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/Theme.MyApp">
        
        <!-- Main launch activity -->
        <activity
            android:name=".MainActivity"
            android:label="@string/main_activity_label">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

        <!-- A secondary activity in a subpackage -->
        <activity
            android:name="com.example.myapp.ui.settings.SettingsActivity"
            android:label="@string/settings_label" />
            
    </application>
</manifest>

Pro Tip #

When you create a new Activity in Android Studio (via File → New → Activity), the IDE automatically adds the correct declaration to your manifest. Take a look at what it generates next time—this is a great way to learn by example!

内容的提问来源于stack exchange，提问作者Abby Layman