Develop Reference

Why onConfigurationChanged doesn't detect screen rotation?

I'm trying to use onConfigurationChanged to detect screen rotation.
Activity
public class MainActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
#Override
public void onConfigurationChanged(#NonNull Configuration newConfig) {
super.onConfigurationChanged(newConfig);
Toast.makeText(getApplicationContext(), "Screen is rotated!", Toast.LENGTH_SHORT).show();
Log.i("ROTATEAPP", "Screen is rotated...");
}
}
AndroidManifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools">
<application
android:allowBackup="true"
android:dataExtractionRules="#xml/data_extraction_rules"
android:fullBackupContent="#xml/backup_rules"
android:icon="#mipmap/ic_launcher"
android:label="#string/app_name"
android:roundIcon="#mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="#style/Theme.ScreenRotate"
tools:targetApi="31">
<activity
android:name=".MainActivity"
android:configChanges="orientation"
android:exported="true">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
<meta-data
android:name="android.app.lib_name"
android:value="" />
</activity>
</application>
</manifest>
I rotated the device (Pixel 3 running Android 12) a few times, and didn't see any Toast or log entry. What's wrong here?

Unable to find explicit activity class error

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.exampl.fitindya"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="9"
android:targetSdkVersion="20" />
<application
android:allowBackup="true"
android:icon="#drawable/ic_launcher"
android:label="#string/app_name"
android:theme="#style/AppTheme" >
<activity
android:name=".MainActivity"
android:label="#string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<!-- Entry for RegisterActivity.class -->
<activity android:name=".RegisterActivity"
android:label="Register New Account"></activity>
</application>
Don't know why this error is appearing and application crashes. please help guys.can there be any problem anywhere else
here is my class file
public class MainActivity extends ActionBarActivity {
Button login_b1;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,WindowManager.LayoutParams.FLAG_FULLSCREEN);
setContentView(R.layout.activity_main);
TextView registerScreen = (TextView) findViewById(R.id.link_to_register);
// Listening to register new account link
registerScreen.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
// Switching to Register screen
Intent i = new Intent(getApplicationContext(), RegisterActivity.class);
startActivity(i);
}
});
}
}

Place this code below the register Activity. I guess that should be the error
<intent-filter>
<action android:name="android.intent.action.DEFAULT" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>

Timer Not working in Android Eclipse

Timer is not working. after few second it should goto another activity
public class intro extends Activity {
int count=0;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,WindowManager.LayoutParams.FLAG_FULLSCREEN);
setContentView(R.layout.intro);
final Toast tosta = Toast.makeText(this, String.valueOf(count+"."), Toast.LENGTH_SHORT);
final Timer timer = new Timer();
timer.scheduleAtFixedRate(new TimerTask() {
#Override
public void run() {
count++;
if(count == 5){
Intent app = new Intent("com.jasrajcomputers.MainActivity");
startActivity(app);
}
tosta.show();
}
}, 1000, 1000);
}}
but after 5 sec app unfortunately has stopped.
manifext.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.jasrajcomputers"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="16"
android:targetSdkVersion="17" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<application
android:allowBackup="true"
android:icon="#drawable/ic_launcher"
android:theme="#style/noactionbarvirat"
android:label="#string/app_name" >
<activity
android:name=".intro"
android:label="#string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
<application
android:allowBackup="true"
android:icon="#drawable/ic_launcher"
android:label="#string/app_name"
android:theme="#style/AppTheme" >
<activity
android:name="com.jasrajcomputers.MainActivity"
android:label="#string/app_name" >
<intent-filter>
<action android:name="com.jasrajcomputers.MainActivity" />
<category android:name="android.intent.category.DEFAULT" />
</intent-filter>
</activity>
</application>
</manifest>
MY LOGCAT:
07-12 12:46:38.979: E/AndroidRuntime(14495): FATAL EXCEPTION: Timer-0
07-12 12:46:38.979: E/AndroidRuntime(14495): android.content.ActivityNotFoundException: No Activity found to handle Intent { act=com.jasrajcomputers.MainActivity }
07-12 12:46:38.979: E/AndroidRuntime(14495): at android.app.Instrumentation.checkStartActivityResult(Instrumentation.java:1697)
07-12 12:46:38.979: E/AndroidRuntime(14495): at android.app.Instrumentation.execStartActivity(Instrumentation.java:1492)
07-12 12:46:38.979: E/AndroidRuntime(14495): at android.app.Activity.startActivityForResult(Activity.java:3388)
07-12 12:46:38.979: E/AndroidRuntime(14495): at android.app.Activity.startActivityForResult(Activity.java:3349)
07-12 12:46:38.979: E/AndroidRuntime(14495): at android.app.Activity.startActivity(Activity.java:3584)
07-12 12:46:38.979: E/AndroidRuntime(14495): at android.app.Activity.startActivity(Activity.java:3552)
07-12 12:46:38.979: E/AndroidRuntime(14495): at com.jasrajcomputers.intro$1.run(intro.java:72)
07-12 12:46:38.979: E/AndroidRuntime(14495): at java.util.Timer$TimerImpl.run(Timer.java:284)

Just have
<application
android:allowBackup="true"
android:icon="#drawable/ic_launcher"
android:theme="#style/noactionbarvirat"
android:label="#string/app_name" >
<activity
android:name=".intro"
android:label="#string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity
android:name=".MainActivity"
android:label="#string/app_name" >
</activity>
</application>
Use Explicit intents
Intent app = new Intent(intro.this, MainActivity.class);
Remove
<application
android:allowBackup="true"
android:icon="#drawable/ic_launcher"
android:label="#string/app_name"
android:theme="#style/AppTheme" >
<activity
android:name="com.jasrajcomputers.MainActivity"
android:label="#string/app_name" >
<intent-filter>
<action android:name="com.jasrajcomputers.MainActivity" />
<category android:name="android.intent.category.DEFAULT" />
</intent-filter>
</activity>
</application>
Update :
Timer is not required here. You can use a Handler instead.
Quoting docs
Explicit intents specify the component to start by name (the
fully-qualified class name). You'll typically use an explicit intent
to start a component in your own app, because you know the class name
of the activity or service you want to start. For example, start a new
activity in response to a user action or start a service to download a
file in the background.

Use a Handler
new Handler().postDelayed(new Runnable(){
#Override
public void run() {
Intent app = new Intent("com.example.MainActivity");
startActivity(app);
}
}, 5000);

Try to replace this code :
Intent app = new Intent("com.jasrajcomputers.MainActivity");
With this code :
Intent app = new Intent(intro.this,MainActivity.class);
Note :
MainActivity must be define in AndroidManifest.xml

Android app force closing after splash screen

I have a splash screen with a timer that runs for 3 seconds. After the 3 seconds it is supposed to auto load another activity called Dashboard. I made a new class that I want to have load after the splash screen called WelcomeSplash. I changed the classes in the splash screen from Dashboard to WelcomeSplash and the app force closes and the logcat says it has a null point exception. Here is the snip of code from the splash class and logcat snip.
02-13 23:18:46.826: E/AndroidRuntime(2475): FATAL EXCEPTION: main
02-13 23:18:46.826: E/AndroidRuntime(2475): java.lang.RuntimeException: Unable to start
activity ComponentInfo{com.magicbuddy.gamble/com.magicbuddy.gamble.welcomeSplash}:
java.lang.NullPointerException
02-13 23:18:46.826: E/AndroidRuntime(2475): at
android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2059)
Here is the snip of the Splash code
startActivity(new Intent(Splash.this, welcomeSplash.class));
When I change the welcomeSPlash.class to Dashboard.class the app does not force close. Here is the welcomeSplash Activity,
public class welcomeSplash extends Activity implements OnClickListener {
Button btnskip;
Button btnplay;
#Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.welcome);
btnskip =(Button) findViewById(R.id.btnSkip);
btnskip.setOnClickListener(this);
btnplay =(Button) findViewById(R.id.btnOk);
btnplay.setOnClickListener(this);
}
public void onClick(View v) {
switch (v.getId()) {
case R.id.btnSkip:
Intent a = new Intent(welcomeSplash.this, Dashboard.class);
startActivity(a);
break;
case R.id.btnOk:
Intent i = new Intent(welcomeSplash.this, Profile.class);
startActivity(i);
break;
}
}
}
THe manifest is copied below too.
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.magicbuddy.gamble"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="17" />
<application
android:allowBackup="true"
android:icon="#drawable/ic_launcher"
android:label="#string/app_name"
android:theme="#style/AppTheme" >
<activity
android:name="com.magicbuddy.gamble.Splash"
android:label="#string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity
android:name="com.magicbuddy.gamble.welcomeSplash"
android:label="#string/app_name" >
<intent-filter>
<action android:name="com.magicbuddy.gamble.Dashboard" />
<category android:name="android.intent.category.DEFAULT" />
</intent-filter>
</activity>
<activity
android:name="com.magicbuddy.gamble.Dashboard"
android:label="#string/app_name" >
</activity>
<activity
android:name="com.magicbuddy.gamble.MainActivity"
android:label="#string/app_name" >
</activity>
<activity
android:name="com.magicbuddy.gamble.Player"
android:label="#string/app_name" >
</activity>
<activity
android:name="com.magicbuddy.gamble.Menu"
android:label="#string/app_name" >
</activity>
<activity
android:name="com.magicbuddy.gamble.Popup"
android:label="#string/title_activity_popup" >
</activity>
</application>
</manifest>

Remove this code from your menifest
<intent-filter>
<action android:name="com.magicbuddy.gamble.Dashboard" />
<category android:name="android.intent.category.DEFAULT" />
</intent-filter>

java.lang.ClassCastException: android.app.Application cannot be cast to roboguice.application.RoboApplication

example using roboguice.
This code get ClassCastException.
public class MainActivity extends RoboActivity{
#InjectView(R.id.text)
TextView name;
#InjectView(R.id.imageView1)
ImageView imageView;
Drawable icon;
#InjectResource(R.string.app_name)
String myName;
#Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
all jar files are already included.
My manifest.xml is here..
find this here.
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.roboguice"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="17" />
<application
android:allowBackup="true"
android:icon="#drawable/ic_launcher"
android:label="#string/app_name"
android:theme="#style/AppTheme" >
<activity
android:name="com.example.roboguice.MainActivity"
android:label="#string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
no changes in manifest.xml.
if required then say.

Try this way
<application
android:name="roboguice.application.RoboApplication" // UPDATE HERE
android:allowBackup="true"
android:icon="#drawable/ic_launcher"
android:label="#string/app_name"
android:theme="#style/AppTheme" >

Add this following line in application tag in AndroidManifest.xml
android:name="roboguice.application.RoboApplication"
#see [More details][1] http://code.google.com/p/roboguice/source/browse/roboguice/src/main/java/roboguice/application/RoboApplication.java?r=b6ae6aeaf9417826a2359fd779814af839557ca1