Android studio 中的登录和注册表单无法解析 class

Question

I am new to programming and need a little bit of noob assistance please. I am busy completing the following tutorial: https://www.androidtutorialpoint.com/androidwithphp/login-and-registration-form-in-android/#ulp-EvSUMG7gujVVNOTG I am having an error that my manifest cannot resolve my classes.:

Manifest:
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.holliacc">
    <uses-permission android:name="android.permission.INTERNET" />
    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:supportsRtl="true"
        android:theme="@style/AppTheme" >
        <activity android:name=".LoginActivity" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <activity android:name=".RegisterActivity"/>
        <activity android:name=".UserActivity" />
    </application>
</manifest>

Error log:

E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.example.holliacc, PID: 17425
    java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.holliacc/com.example.holliacc.LoginActivity}: java.lang.ClassNotFoundException: Didn't find class "com.example.holliacc.LoginActivity" on path: DexPathList[[zip file "/data/app/~~kZF1Y8ZOF3c7KaMf5oydhg==/com.example.holliacc-p6ZfAvZpZQUhmyYVsggi2w==/base.apk"],nativeLibraryDirectories=[/data/app/~~kZF1Y8ZOF3c7KaMf5oydhg==/com.example.holliacc-p6ZfAvZpZQUhmyYVsggi2w==/lib/x86, /system/lib, /system_ext/lib, /product/lib]]
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3258)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3484)
        at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:83)
        at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)

I have attempted to reach out to the author with no luck. Additionally i have googled but i don't think i understand enough yet to answer my question.

Please help? Also if anyone else has done this tutuorial. where is the UserActivity class??

Thanks all!

Answer 1

add this line in the buildgradle

implementation 'com.android.support:multidex:1.0.3'

and in the same gradle add

defaultConfig {
        applicationId "com.example.project"
        minSdkVersion 21
        targetSdkVersion 29
        versionCode 1
        versionName "1.0"
        multiDexEnabled true  //add this line
        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
    }

after synced project Clean Project from Build -> Clean project