Java Question ClassCastException

Johan Schoeman · Mar 19, 2017

I am trying to do a shortcut wrap for a B4A member. By "shortcut" I mean that the B4A wrapper purely kick starts the original project as a separate activity. I have done it numerous times with similar projects but this project refuses to cooperate. The error that I get is the following:

B4X:

java.lang.RuntimeException: Unable to start activity ComponentInfo{JHS.SkyTest/com.skytree.epubtest.HomeActivity}: java.lang.ClassCastException: android.app.Application cannot be cast to com.skytree.epubtest.SkyApplication

The B4A wrapper is simple:

B4X:

public class skytestWrapper extends AbsObjectWrapper<HomeActivity> {

   
    @Hide
    public static BA ba;
    @Hide
    public static String eventName;
    private static HomeActivity cv;
    private IOnActivityResult ion;
   
   
    Intent izx;
   
    public void Initialize(BA paramBA, String paramString) {
        eventName = paramString.toLowerCase(BA.cul);
        ba = paramBA;

        HomeActivity cv = new HomeActivity();
        String str = paramString.toLowerCase(BA.cul);
   
        setObject(cv);
        izx = new Intent(BA.applicationContext, HomeActivity.class);   
    }   


     public void startSkyTest() {
        ion = new IOnActivityResult() {
           
            @Override
            public void ResultArrived(int arg0, Intent data) {
               
            }
        };
        ba.startActivityForResult(ion, izx);
    }
   
   
}

The error occurs in class HomeActivity.java as

B4X:

Caused by: java.lang.ClassCastException: android.app.Application cannot be cast to com.skytree.epubtest.SkyApplication
at com.skytree.epubtest.HomeActivity.onCreate(HomeActivity.java:303)

Line 303 of HomeActivity.java is as follows:

B4X:

app = (SkyApplication)getApplication();

app is declared as type SkyApplication in class HomeActivity.java

The projects Manifest file looks as follows:

B4X:

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.skytree.epubtest"
    android:versionCode="2"
    android:versionName="1.2" >

    <!-- tagetgetSdkVersion should be 16. -->
    <uses-sdk
        android:minSdkVersion="11"
        android:targetSdkVersion="19" />
    <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
    <uses-permission android:name="android.permission.READ_PHONE_STATE" />
    <uses-permission android:name="android.permission.VIBRATE" />
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
    <uses-permission android:name="android.permission.ACCESS_WIFI_STATE"/>   
    <uses-permission android:name="android.permission.WRITE_SETTINGS" />
    <uses-permission android:name="android.permission.CHANGE_WIFI_STATE"/>
   
   
<application
        android:name="com.skytree.epubtest.SkyApplication"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:largeHeap="true"
        android:hapticFeedbackEnabled="false"
        android:hardwareAccelerated="true"
         >
        <activity
            android:name="com.skytree.epubtest.HomeActivity"
            android:configChanges="keyboard|keyboardHidden|orientation|screenLayout|uiMode|screenSize"           
            android:label="@string/app_name"
            android:theme="@android:style/Theme.NoTitleBar" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <activity
            android:name="com.skytree.epubtest.BookViewActivity"
            android:configChanges="keyboard|keyboardHidden|orientation|screenLayout|uiMode|screenSize"
            android:label="BookView"
            android:theme="@android:style/Theme.Light.NoTitleBar" >
        </activity>
        <activity
            android:name="com.skytree.epubtest.MagazineActivity"
            android:configChanges="keyboard|keyboardHidden|orientation|screenLayout|uiMode|screenSize"
            android:label="Magazine"
            android:theme="@android:style/Theme.NoTitleBar" >
        </activity>

        <service
            android:name="com.skytree.epubtest.LocalService"
            android:enabled="true" >
        </service>

        <activity
            android:name="com.skytree.epubtest.SettingActivity"
            android:configChanges="keyboard|keyboardHidden|orientation|screenLayout|uiMode|screenSize"
            android:label="@string/title_activity_setting" >
        </activity>
    </application>

</manifest>

My B4A manifest file looks as follows:

B4X:

AddManifestText(
<uses-sdk android:minSdkVersion="11" android:targetSdkVersion="19"/>
<supports-screens android:largeScreens="true"
    android:normalScreens="true"
    android:smallScreens="true"
    android:anyDensity="true"/>)
'AddApplicationText(android:name = "com.skytree.epubtest.SkyApplication")

SetApplicationAttribute(android:icon, "@drawable/icon")
SetApplicationAttribute(android:label, "$LABEL$")
'End of default text.
       
AddApplicationText(<service
            android:name="com.skytree.epubtest.LocalService"
            android:enabled="true" >
        </service>)       
       
AddApplicationText(

<activity
            android:name="com.skytree.epubtest.HomeActivity"
            android:configChanges="keyboard|keyboardHidden|orientation|screenLayout|uiMode|screenSize"           
            android:label="@string/app_name"
            android:theme="@android:style/Theme.NoTitleBar" >
        </activity>
        <activity
            android:name="com.skytree.epubtest.BookViewActivity"
            android:configChanges="keyboard|keyboardHidden|orientation|screenLayout|uiMode|screenSize"
            android:label="BookView"
            android:theme="@android:style/Theme.Light.NoTitleBar" >
        </activity>
        <activity
            android:name="com.skytree.epubtest.MagazineActivity"
            android:configChanges="keyboard|keyboardHidden|orientation|screenLayout|uiMode|screenSize"
            android:label="Magazine"
            android:theme="@android:style/Theme.NoTitleBar" >
        </activity>


        <activity
            android:name="com.skytree.epubtest.SettingActivity"
            android:configChanges="keyboard|keyboardHidden|orientation|screenLayout|uiMode|screenSize"
            android:label="@string/title_activity_setting" >
        </activity>)

I have added the permission that are in the project's Manifest in the wrapper

B4X:

@Permissions(values={"android.permission.INTERNET", "android.permission.ACCESS_NETWORK_STATE", "android.permission.READ_PHONE_STATE",
                     "android.permission.VIBRATE", "android.permission.WRITE_EXTERNAL_STORAGE", "android.permission.ACCESS_WIFI_STATE",
                     "android.permission.WRITE_SETTINGS", "android.permission.CHANGE_WIFI_STATE"})

My question is:
1. Is my Manifest correct and if not is that why I get the error?
2. If not my Manifest - why the ClassCastException?

Will appreciate some help with this.

Thanks

JS

Erel · Mar 19, 2017

The generated manifest doesn't match the manifest code you posted.

You should set the application class with:

B4X:

SetApplicationAttribute(android:name, "com.skytree.epubtest.SkyApplication")

Johan Schoeman · Mar 19, 2017

Erel said:
The generated manifest doesn't match the manifest code you posted.

You should set the application class with:

B4X:

SetApplicationAttribute(android:name, "com.skytree.epubtest.SkyApplication")

Thanks Erel - manifest is now looking like this and it is working:

B4X:

'This code will be applied to the manifest file during compilation.
'You do not need to modify it in most cases.
'See this link for for more information: https://www.b4x.com/forum/showthread.php?p=78136
AddManifestText(
<uses-sdk android:minSdkVersion="11" android:targetSdkVersion="19"/>
<supports-screens android:largeScreens="true"
    android:normalScreens="true"
    android:smallScreens="true"
    android:anyDensity="true"/>)
'AddApplicationText(android:name = "com.skytree.epubtest.SkyApplication")

SetApplicationAttribute(android:icon, "@drawable/icon")
SetApplicationAttribute(android:label, "@string/app_name")
SetApplicationAttribute(android:name, "com.skytree.epubtest.SkyApplication")
SetApplicationAttribute(android:largeHeap,"true")
SetApplicationAttribute(android:hapticFeedbackEnabled, "false")
SetApplicationAttribute(android:hardwareAccelerated, "true")
'End of default text.
       
AddApplicationText(<service
            android:name="com.skytree.epubtest.LocalService"
            android:enabled="true" >
        </service>)       
       
AddApplicationText(<activity
            android:name="com.skytree.epubtest.HomeActivity"
            android:configChanges="keyboard|keyboardHidden|orientation|screenLayout|uiMode|screenSize"           
            android:theme="@android:style/Theme.NoTitleBar" >
        </activity>
        <activity
            android:name="com.skytree.epubtest.BookViewActivity"
            android:configChanges="keyboard|keyboardHidden|orientation|screenLayout|uiMode|screenSize"
            android:label="BookView"
            android:theme="@android:style/Theme.Light.NoTitleBar" >
        </activity>
        <activity
            android:name="com.skytree.epubtest.MagazineActivity"
            android:configChanges="keyboard|keyboardHidden|orientation|screenLayout|uiMode|screenSize"
            android:label="Magazine"
            android:theme="@android:style/Theme.NoTitleBar" >
        </activity>


        <activity
            android:name="com.skytree.epubtest.SettingActivity"
            android:configChanges="keyboard|keyboardHidden|orientation|screenLayout|uiMode|screenSize"
            android:label="@string/title_activity_setting" >
        </activity>)

Erel · Mar 19, 2017

Note that setting a custom application class means that MultiDex will not work on Android 4.x devices. This is not a big problem but it is worth mentioning in the library thread.

Java Question ClassCastException

Johan Schoeman

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Erel

B4X founder

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