Android不启动默认活动（MainActivity）

Question

I have a very simple widget application with one single activity (MainActivity). At the very beginning I've created MainActivity from BlankActivity template. I filled it a bit later with components and I've added it to AndroidManifest.

The problem is that Android don't launch the activity (the only one).

What I see when app started is white blank view (with topbar with app-name).

I've put a breakpoint and didn't get to it during debug.

I've tried to set DEFAULT category to MainActivity and without it:

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

I've tried to put full or short path to Main Activity:

android:name="pl.test.firstwidget.view.MainActivity"

android:name=".view.MainActivity"

I'm sure my MainActivity is in view package.

• I've tried to uninstall application from emulator, and install app again, but it didn't help.
• I've tried to install app to another emulator - no success
• I've tried to install app to phone - no success.
• I've tried to clean and rebuild my project - no success.
• I've tried to set DefaultActivity in my AndroidStudio run configuration - no success.
• I've tried to set specified activity (MainActivity) in run configuration - no success.

AndroidManifest.xml:

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="pl.test.firstwidget"
    android:versionCode="1"
    android:versionName="1.0">

  <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=".view.MainActivity"
        android:label="@string/app_name"
        android:screenOrientation="portrait">
        <intent-filter>
            <action android:name="android.intent.action.MAIN"/>
            <category android:name="android.intent.category.DEFAULT"/>
            <category android:name="android.intent.category.LAUNCHER"/>
        </intent-filter>
    </activity>

    <receiver android:name=".view.MyWidgetProvider" >
        <intent-filter>
            <action android:name="android.appwidget.action.APPWIDGET_UPDATE" />
        </intent-filter>
        <meta-data android:name="android.appwidget.provider" android:resource="@xml/widget_info" />
    </receiver>

  </application>

</manifest>

MainActivity.java:

package pl.test.firstwidget.view;
(...)

public class MainActivity extends AppCompatActivity {

    @BindView(R.id.ordersNumber) TextView ordersNumber;
    @BindView(R.id.ordersValue) TextView ordersValue;
    @BindView(R.id.lastUpdate) TextView lastUpdate;
    @BindView(R.id.refreshButton) TextView refreshButton;

    @Override
    public void onCreate(Bundle savedInstanceState, PersistableBundle persistentState) {
        super.onCreate(savedInstanceState, persistentState);
        setContentView(R.layout.activity_main);

        ButterKnife.bind(this);
        fillView();
    }

    private void fillView() {
        //empty so far    
    }

    @OnClick(R.id.refreshButton)
    public void refresh() {
        //empty so far
    }

}

build.gradle

apply plugin: 'com.android.application'
apply plugin: 'me.tatarka.retrolambda'

android {
    compileSdkVersion 25
    buildToolsVersion "25.0.2"
    defaultConfig {
        applicationId 'pl.test.firstwidget'
        minSdkVersion 15
        targetSdkVersion 25
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
    productFlavors {
    }
}

dependencies {
    compile fileTree(include: ['*.jar'], dir: 'libs')
    androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', {
        exclude group: 'com.android.support', module: 'support-annotations'
    })

    compile 'com.google.code.gson:gson:2.8.0'
    compile 'com.squareup.retrofit2:retrofit:2.3.0'
    compile 'com.squareup.retrofit2:converter-gson:2.3.0'
    compile 'com.squareup.okhttp3:logging-interceptor:3.8.0'

    compile group: 'joda-time', name: 'joda-time', version: '2.9.9'

    compile 'com.jakewharton:butterknife:8.6.0'
    annotationProcessor 'com.jakewharton:butterknife-compiler:8.8.1'

    compile 'com.android.support:appcompat-v7:25.3.1'
    testCompile 'junit:junit:4.12'
}

Does anybody see what I do wrong?

Answer 1

You need to override public void onCreate(Bundle savedInstanceState) not public void onCreate(Bundle savedInstanceState, PersistableBundle persistentState) which is intended for api 21+ to persist your activity state across restarts

Note Same as onCreate(android.os.Bundle) but called for those activities created with the attribute persistableMode set to persistAcrossReboots (in the manifest otherwise it won't get called hence empty view)

About PersistableBundle

if the activity is being re-initialized after previously being shut down or powered off then this Bundle contains the data it most recently supplied to outPersistentState in onSaveInstanceState(Bundle). Note: Otherwise it is null.

So use

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState, persistentState);
    setContentView(R.layout.activity_main);

    ButterKnife.bind(this);
    fillView();
}

Answer 2

It seems nothing is wrong.

1. You don't need android.intent.category.DEFAULT in the manifest, just android.intent.action.MAIN and android.intent.category.LAUNCHER should work

2. If you are starting Android development, for now, remove all references to butterKnife and don't use it yet; just to verify if it runs.

3. change your onCreate method as Pavneet_Singh answered, but don't use that super just use:

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.id.activity_main);
    // ..code
}