I'm an Android noob and I'm having difficulty finding out something basic about Android.
I currently have an activity_main.xml file.
I want to use this layout when I first start the Android emulator, using Android Studio
Does Android look for a file activity_main.xml and use it as the default layout?
Here's my AndroidManifest.xml:
<application
android:allowBackup="true"
android:icon="#mipmap/ic_launcher"
android:label="#string/app_name"
android:supportsRtl="true"
android:theme="#style/AppTheme" >
<activity android:name=".MainActivity" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
So I understand that this specifies that my .MainActivity will respond to an action.MAIN intent call. What I don't know is what the action.MAIN intent call actually is, and how my activity_main.xml relates to this.
public class MainActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
}
Can anyone provide an explanation or a link to a good primer that explains these basic concepts?
From manifest :
<action android:name="android.intent.action.MAIN" />
Means this activity is the entry point of the application. In your case, the MainActivity starts.
The MainActivity sets up the layout for itself - the line responsible is
setContentView(R.layout.activity_main);
Where it looks for layout file activity_main.xml. This is just the naming convention - feel free to rename the layout file and call the new one from setContentView. It's not required to be called activity_main
Related
Hello everyone this is my first android coding and im trying to switch between activities, but i cant simply find where is my mistake.
Main here;
public class MainActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
protected void start()
{
Intent k= new Intent(MainActivity.this, Try.class);
startActivity(k);
finish();
}
And My manifest is here and my second activity name is "Try";
<application
android:allowBackup="true"
android:icon="#mipmap/ic_launcher"
android:label="#string/app_name"
android:roundIcon="#mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="#style/AppTheme">
<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="com.example.ege.intent.Try"
android:label="#string/app_name" >
</activity>
</application>
Thanks.
I think;
May your class package name is wrong but there should be more information about crash.
Change android:name="com.example.ege.intent.Try"
with Try.class location, if it is same in Manifest.
Just try to Change android:name=".Try"
If you put your error or your log details, I can help you
the method "start()" is unused. use it in "onCreate()" method .
you may add a button . swtich activities by listening the click.
Where do you call start()?. Manifest seems okay but check if your package is right, anyway try would do the same, MainActivity lacks a closing semicolon }
I'm new to Android Application development. I just added another activity tag in my AndroidManifest.xml file but its gives me the following message : Can't resolve symbol 'SecondActivity' Validates resource references inside Android XML files.
I want to know why is this message getting displayed?
Here is my AndroidManifest.xml file :
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.aupadhyay.myfirstapp">
<application
android:allowBackup="true"
android:icon="#mipmap/amiticon"
android:label="#string/app_name"
android:supportsRtl="true"
android:theme="#style/AppTheme">
<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=".SecondActivity">
<intent-filter>
<action android:name="anything" />
<category android:name="android.intent.category.DEFAULT" />
</intent-filter>
</activity>
</application>
</manifest>
And this is my SecondActivity.java file :
import android.support.v7.app.AppCompatActivity;
public class SecondActivity extends AppCompatActivity {
}
Picture :
Consider the following:
Remove the intent-filter inside your second activity unless you really need that.
In your second activity, override onCreate method
#override
public void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.second_activity_layout);
}
Did you create a layout for your second activity? It seems your activity is empty - although this might not be the cause of your problem. Also what is the location of your SecondActivity, a different package or in the same place as the first activity?
As shown in your code, your second activity doesn't seem to have any of that layout stuff!
I hope this helps you!
It seems your SecondActivity doesn't belongs to the package "com.aupadhyay.myfirstapp", So move it to src of the "com.aupadhyay.myfirstapp" package where ever it currently belongs to.
As i am new to android programming, I don't know how to call a certain class and/or certain activity first.
For example i have two classes viz. 1) Login.java 2) Create.java and two xml files associated with them are activity_main.xml and create_new.xml respectively.
So how can i make Login.java run first with activity_main.xml as screen?
in login java use this
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);}
in create java us this
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.create_new);
in androidmanifest
<activity
android:name=".Login"
android:label="#string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
and another activities
<activity android:name=".MainActivity" ></activity>
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.your.package"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="10"
android:targetSdkVersion="19" />
<uses-permission android:name="android.permission.INTERNET" />
<application
android:allowBackup="true"
android:icon="#drawable/ic_launcher"
android:label="#string/app_name"
android:theme="#style/AppTheme" >
<activity
android:name="com.example.your.package.activity.Login"
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.example.your.package.activity.Create"
android:label="#string/app_name" >
</activity>
</application>
</manifest>
In this case, the intent-filter of LOGIN activity specifies that the intent with action of MAIN and category of LAUNCHER will be caught by it, aka it is where the application starts.
Afterwards,
public class Login extends Activity
{
//honestly I'd name this class LoginActivity and same in the XML
#Override
public void onCreate(Bundle saveInstanceState)
{
super.onCreate(saveInstanceState);
setContentView(R.layout.activity_main);
}
....
}
Also look at this example to learn how to use Fragments:
NullPointerException accessing views in onCreate()
from the intent filters you decalre in the android manifest file of your project;see the image
You declare an intent filter in the activity tag something like shown in the image for making it the first activity of your application.and if there are other activities in your app having intent filters than you have to just change the capital letter MAIN to DEFAULT in the intent filter tag
You will find AndroidManifest file like in the following image in your project
I am using Win 7.0, Eclipse and android SDK. I want to add new activity in AndroidManifest.xml Application tab as it is shown in this tutorial Android Development – Adding Screens & Button Handlers
I add an Activity name to my manifest but it does not automatically turn it into a link. e.g. I cannot click the "Name"(It is not a hyperlink as shown in the article), thus I cannot create my class.
Can You Help me? what is the problem ?
1.Go to the Androidmanifest.xml file and add the activity inside the tag
if your activity name is secondAct.
2.Create a class named secondAct.
<application android:icon="#drawable/icon" android:label="#string/app_name">
<activity android:name=".Project1Activity"
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=".secondAct"></activity>
<activity android:name=".third"></activity>
</application>
3 . if you are using a button for going to next activity, use the following code in secondAct.java
Button fbtn=(Button)findViewById(R.id.sbtn);
fbtn.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
// TODO Auto-generated method stub
Intent sec=new Intent(secondAct.this,com.asish.third.class);
startActivity(sec);
}
});
Go to the small tab underneath that says AndroidManifest.xml and shows you the XML code for it. It should look like this:
<application android:label="#string/app_name" android:icon="#drawable/icon">
<activity android:name=".ApplicationName"
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=".AnotherActivity"></activity>
</application>
Okay, click on ADD, then select the top box that says "Create a new element at the top level, in Application" and then you should get a box with linkable NAME*.
You need to create the class first, then point to that class in your manifest... just putting the class name in the manifest is not enough. It will not automatically create it for you.
Also, it is easier to create the class first because then Eclipse will autocomplete the class name/path for you.
EDIT: AH HAH! I see what link you are talking about...
Yeah, you need to actually create the class first for that to appear.
I'm trying to create a simple app, whose main task is to open the browser on defined URL.
I've created first Activity:
public class MyActivity extends Activity {
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
//setContentView(R.layout.main);
Intent myIntent = new Intent(Intent.ACTION_VIEW,
Uri.parse("http://my.url.tld"));
startActivity(myIntent);
}
Here's my AndroidManifest.xml:
<manifest ...>
<application ...>
<activity android:name=".MyActivity" ...>
<intent-filter>
<action android:name="android.intent.action.MAIN"/>
<category android:name="android.intent.category.LAUNCHER"/>
</intent-filter>
</activity>
This code is fully functional, but before it opens the browser, it displays a black background - blank app GUI. I didn't figured out, how to go directly do the browser (without displaying the GUI).
Anyone knows?
Add this theme declaration to your activity definition in you manifest
<activity android:name=".MyActivity"
android:theme="#android:style/Theme.Translucent.NoTitleBar"
>
Be careful with this, you must call finish(); from your activity after you are done with it otherwise users could get stuck with an invisible activity that prevents them from interacting the phonetop.