Creating a new Activity, makes a whole new application? - java

Im new to android, and when i read "Create New Activity" i was under the impression it creates a new "Window/Layout/Screen".
When i start making my own application i see
Main.java
is one application and
SecondActivity.java
is another app in my Emulators menu?
Why is that and how can i go about making one app with multiple windows as apposed to multiple applications essentially?
Manifest
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.ryan.bidorbuyapp" >
<application
android:allowBackup="true"
android:icon="#mipmap/bidorbuy_logo"
android:label="#string/app_name"
android:theme="#style/AppTheme" >
<activity
android:name=".FullscreenActivity"
android:configChanges="orientation|keyboardHidden|screenSize"
android:label="#string/app_name"
android:theme="#style/FullscreenTheme" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity
android:name=".SearchResults"
android:configChanges="orientation|keyboardHidden|screenSize"
android:label="#string/title_activity_search_results"
android:parentActivityName=".FullscreenActivity"
android:theme="#style/FullscreenTheme" >
<meta-data
android:name="android.support.PARENT_ACTIVITY"
android:value="com.ryan.bidorbuyapp.FullscreenActivity" />
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
thanks


Look at your AndroidManifest.xml there is the problem. Your activities have Launcher between it's tags. Only one activity must have LAUNCHER tag
Only one activity must have
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>


You should understand what is an Activity before starting to developing an android application. You can think an activity as a page in web. There can be one or more and every activity includes their own contents.
When you create a new activity in your project, you should navigate by doing some operations in another activity. Intent helps you at this point to navigate one activity to the another.
Your problem is that, you should check your AndroidManifest.xml file. Please check the declaration of intent here. I think you will solve it after making a search about Intent.

Related

How to add a Login Page/Activity to a Pre-Existing Main Activity? [duplicate]

I have created the meat and guts of my application but I want to add a different activity that will be the starting point (sort of a log-in screen).
Couple questions:
1 I have a fairly decent handle on how to switch between activities (based on this article: http://www.linux-mag.com/id/7498) but I'm not sure how to go about creating a new one (with eclipse).
2 Once I have a new activity created, how can I set it as the default activity of my application? I presume I could just change the name of the classes...but is there a more elegant way to handle that (maybe within the AndroidManifest.xml)?

Yes, you use the AndroidManifest.xml file. You can actually even have more than one launcher activity specified in your application manifest. To make an activity seen on the launcher you add these attributes to your activity in the manifest:
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>

Go to AndroidManifest.xml in the root folder of your project and change the Activity name which you want to execute first.
Example:
<activity android:name=".put your started activity name here"
android:label="#string/app_name">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>

If you are using Android Studio and you might have previously selected another Activity to launch.
Click on Run > Edit configuration and then make sure that Launch default Activity is selected.

<application
android:icon="#drawable/YOUR_ICON" <!-- THIS ICON(IMAGE) WILL BE SHOWN IN YOUR APPS -->
android:label="MY APP NAME " > <!-- HERE LABEL(APP NAME) -->
<activity
android:name=".application's starting activity" <!-- (.)dot means current dir, if your activity is in another package then give full package name ex: com.xxx.Activity -->
android:label="LABEL FOR ACTIVITY "
android:screenOrientation="portrait" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>

Follow to below instructions:
1:) Open your AndroidManifest.xml file.
2:) Go to the activity code which you want to make your main activity like below.
such as i want to make SplashScreen as main activity
<activity
android:name=".SplashScreen"
android:screenOrientation="sensorPortrait"
android:label="City Retails">
</activity>
3:) Now copy the below code in between activity tags same as:
<activity
android:name=".SplashScreen"
android:screenOrientation="sensorPortrait"
android:label="City Retails">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
and also check that newly added lines are not attached with other activity tags.

This is easy to fix.
Changes to the Launcher activity are also stored in the Debug configuration.
Go to Run > Debug Configurations and edit the setting.
There is also a similar setting in Intellij under Run > Edit Configurations select Run default Activity and it will no longer save the setting in this fashion.

It's simple. Do this, in your Manifest file.
<activity
android:name="Your app name"
android:label="#string/app_name">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.HOME" />
<category android:name="android.intent.category.DEFAULT" />
</intent-filter>
</activity>

<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>

Just go to your AndroidManifest.xml file and add like below
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
then save and run your android project.

You add this you want to launch activity
android:exported="true" in manifest file like
<activity
android:name=".activities.activity.MainActivity"
android:windowSoftInputMode="adjustPan"
android:exported="true"/>
<activity
Open java file of this activity and right click then click on Run 'main Activity'
OR
Open java file of this activity and press Ctrl+Shift+F10.

In a recent project I changed the default activity in AndroidManifest.xml with:
<activity android:name=".MyAppRuntimePermissions">
</activity>
<activity android:name=".MyAppDisplay">
<intent-filter>
<action android:name="android.intent.activity.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
In Android Studio 3.6; this seems to broken. I've used this technique in example applications, but when I use it in this real-world application it falls flat. The IDE once again reports:
Error running app: Default activity not found.
The IDE still showed a configuration error in the "run app" space in the toolbar (yellow arrow in this screenshot)
To correct this error I've tried several rebuilds of the project, and finally File >> "Invalidate Cache/Restart". This did not help. To run the application I had to "Edit Configurations" and point at the specific activity instead of the default activity:

In AndroidManifest.xml
I changed here the first activity to be MainActivity4 instead of MainActivity:
Before:
<activity android:name=".MainActivity" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity android:name=".MainActivity2" />
<activity android:name=".MainActivity3" />
<activity android:name=".MainActivity4" />
<activity android:name=".MainActivity5" />
<activity android:name=".MainActivity6"/>
After:
<activity android:name=".MainActivity" />
<activity android:name=".MainActivity2" />
<activity android:name=".MainActivity3" />
<activity android:name=".MainActivity4" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity android:name=".MainActivity5" />
<activity android:name=".MainActivity6"/>

For anyone getting errors in their debug\AndroidManifest.xml file make sure that you include the tag!
"<activity android:name=".MainActivity>"
For example:
<activity android:name=".MainActivity"><intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter></activity>

Android Studio Layout is not Responding

I recently have added a layout and a java file connecting it to my java code file which is taking and giving actual output by implementing an algorithm but the second layout when opened in my phone it does not react to any of the two buttons clicked on it.
Seems like an error in AndroidManifest file.
here is Manifest file code,
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.myapplicationgeneric">
<application
android:allowBackup="true"
android:label="#string/app_name2"
android:icon="#mipmap/jug_black_trasnparent"
android:roundIcon="#mipmap/jug_black_trasnparent"
android:supportsRtl="true"
android:theme="#style/AppTheme">
<activity android:name=".Next"></activity>
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity android:name=".connectorclass">
<intent-filter>
<action android:name="android.intent.action.ANSWER"/>
<category android:name="android.intent.category.Calculator"/>
</intent-filter>
</activity>
</application>
<uses-sdk android:minSdkVersion="3" />
</manifest>
here connectorclass.java is linked to the Layout not Responding named something xyz..

Just remove the intent filter for "connectorclass".

In AndroidManifest.xml file, you provide two intent files. That doesn't need it. Always try to add one intent-filter on your activity and this activity is your lancer activity. So remove the second intent-filter from connectorclass activity.
Then add below code on your button onClickListener
Intent intent = new Intent(MainActivity.class, connectorclass.class);
startActivity(intent);

you can remove
<intent-filter>
<action android:name="android.intent.action.ANSWER"/>
<category android:name="android.intent.category.Calculator"/>
</intent-filter>
in android manifest and can start activity using class name by default
like this
Intent intent = new Intent(this, connectorclass.class);
startActivity(intent);
try this

Figuring out the launcher on this Android Studio Github project

Still a little bit new to Android studio and app development. On this project: https://github.com/watabou/pixel-dungeon, which file is acting as the MainActivity.java file? As in, which file is the main launcher of the application, how do you tell?

The activity with the intent filters android.intent.action.MAIN and android.intent.category.LAUNCHER is the launcher for any app,
Just check which activity it has bellow intent filter that is launcher,
<intent-filter >
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
In that project PixelDungeon is the launcher activity.

Your launcher activity is defined in your android manifest (AndroidManifest.xml), it should look like this:
<activity
android:name=".activity.Login_screen"
android:label="Activity Validation">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
For your case, if you want to edit your launcher activity just change ".activity.Login_screen" for the activity you want to display on launch. However, make sure that there are no duplicate definitions.
As you can see in your code:
<activity
android:label="#string/app_name"
android:name=".PixelDungeon"
android:screenOrientation="portrait">
<intent-filter >
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>

Trying to have main menu and submenu classes

So my original problem was that in my manifest my menu wasent loading ie
<activity
android:name=".MainMenu"
android:label="#string/app_name" >
<intent-filter>
<action android:name="com.th3ramr0d.learnar670_1.MAINMENU" />
<category android:name="android.intent.category.DEFAULT" />
</intent-filter>
</activity>
This was fixed by loading it at startup ie
<activity
android:name=".MainMenu"
android:label="#string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
So now my main menu works. However, the buttons inside MainMenu.xml will take you to another .xml file with more buttons. So now I have the same problem. I created another class called SubMenuChapter3 and put it in the manifest as such.
<activity
android:name=".SubMenuChapter3"
android:label="#string/app_name" >
<intent-filter>
<action android:name="com.th3ramr0d.learnar670_1.SUBMENUCHAPTER3" />
<category android:name="android.intent.category.DEFAULT" />
</intent-filter>
</activity>
Now this doesnt work I am assuming for the same reason as before with mainmenu. Doesnt crash or give me errors. It just wont open the submenuchapter3 class. I forced the submenuchapter3 class to open by putting
startActivity(new Intent("com.th3ramr0d.learnar670_1.SUBMENUCHAPTER3"));
directly into the MainMenu class outside of an onclick just to see if it was working. When I do that it opens the chapter_3.xml like it is supposed to and the button works. Thanks for the help.

You misunderstood <intent-filter> tag and the way you start activities.
Also maintain proper terminology - Menu and Activity are completely different things.
Everything you need to know about Activities can be found here: Activities | Android Developers
Example:
This entry in AndroidManifest.xml says "show the MainMenu Activity as icon in the launcher":
<activity
android:name=".MainMenu"
android:label="#string/app_name">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
EDIT: This allows Android to start MainActivity. It will also show in the installed app list.
The following Activity will not be displayed in launcher but can be opened from the app:
<activity android:name=".SubMenuChapter3"/>
EDIT: This allows Android to start SubMenuChapter3. It won't show in the installed app list.
These lines say "open the SubMenuChapter3 Activity":
Intent i = new Intent(this, SubMenuChapter3.class);
startActivity(i);
EDIT: You call this code from inside the onClick method inside MainMenu. It will launch SubMenuChapter3.

Make home intent take to specific application activity?

I've built a project that contains different packages and activities, say:
com.example.package1.Activity1
com.example.package2.Activity2
The first package holds a launcher. On my project manifest file this activity is listening to the home intent:
// Launcher
<activity android:name=".package1.Activity1" android:label="#string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.HOME" />
<category android:name="android.intent.category.DEFAULT" />
</intent-filter>
</activity>
// package2.activity1
<activity android:name=".package2.activity1" android:label="#string/package2_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
My problem is that when a user clicks Home the launcher isn't opened, instead the user is taken to the last opened activity of the app. EG: User opens package2.MainActivity from default launcher > goes to another app > clicks home > package2.MainActivity is opened again.
Is this normal? How do I make sure the device Home button takes to .package1.activity1?

If you are trying to create a HOME-screen replacement, then the activity for that needs to have the following in its <activity> tag in the manifest:
android:launchMode="singleInstance"
This will ensure that only one instance of this activity ever exists and that when this activity launches other activities that they will all go into new tasks and not be a part of the HOME-screen replacement's task.

I am not sure but please try to this code:
// package2.activity1
<activity android:name=".package2.activity1" android:label="#string/package2_name" >
<intent-filter>
<action android:name="android.intent.action.View" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>

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