Data Transfer between activities and Database
- 1. Data Transfer between Activities & Databases Lecturer Faiz Ur Rehman University of Mianwali
- 2. Intent • Android uses Intent for communicating between the components of an Application and also from one application to another application. • Intent are the objects which is used in android for passing the information among Activities in an Application and from one app to another also. Intent are used for communicating between the Application components and it also provides the connectivity between two apps
- 5. Example Intent intent = new Intent(getApplicationContext(), SecondActivity.class); startActivity(intent); getApplicationContext() returns the context for your foreground activity.
- 7. Explicit Intent: • Explicit Intents are used to connect the application internally. • Explicit Intent work internally within an application to perform navigation and data transfer. • Example. Intent intent = new Intent(getApplicationContext(), SecondActivity.class); startActivity(intent);
- 8. Implicit Intent: • In Implicit Intents we do need to specify the name of the component. • We just specify the Action which has to be performed and further this action is handled by the component of another application. • The basic example of implicit Intent is to open any web page • Example Intent intentObj = new Intent(Intent.ACTION_VIEW); intentObj.setData(Uri.parse("https://www.abhiandroid.com")); startActivity(intentObj);
- 9. Intent Uses in android: 1. Intent for an Activity: • Every screen in Android application represents an activity. To start a new activity you need to pass an Intent object to startActivity() method. This Intent object helps to start a new activity and passing data to the second activity
- 10. 2. Intent for Services: • Services work in background of an Android application and it does not require any user Interface. Intents could be used to start a Service that performs one-time task • (for example:Downloading some file)
- 11. 3. Intent for Broadcast Receivers: • There are various message that an app receives, these messages are called as Broadcast Receivers. (For example, a broadcast message could be initiated to intimate that the file downloading is completed and ready to use). Android system initiates some broadcast message on several events, such as System Reboot, Low Battery warning message etc. 4. Display a list of contacts 5. Dial a phone call etc.
- 12. Implicit Example Code • Intent intent=new Intent(Intent.ACTION_VIEW); intent.setData(Uri.parse("http://www.tutlane.com")); startActivity(intent); • (ACTION_VIEW) to open the defined URL (http://www.tutlane.com) in browser within the device
- 13. XML Code • <?xml version="1.0" encoding="utf-8"?> <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" tools:context="com.tutlane.intents.MainActivity"> <EditText android:layout_width="wrap_content" android:layout_height="wrap_content" android:id="@+id/urlText" android:layout_alignParentTop="true" android:layout_centerHorizontal="true" android:layout_marginTop="100dp" android:ems="10" /> <Button android:layout_width="wrap_content" android:layout_height="wrap_content" android:id="@+id/btnNavigate" android:layout_below="@+id/urlText" android:text="Navigate" android:layout_centerHorizontal="true" /> </RelativeLayout>
- 14. MainActivity.java • package com.tutlane.intents; import android.content.Intent; import android.net.Uri; import android.support.v7.app.AppCompatActivity; import android.os.Bundle; import android.view.View; import android.widget.Button; import android.widget.EditText; public class MainActivity extends AppCompatActivity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); • final EditText editText = (EditText)findViewById(R.id.urlText); Button btn = (Button) findViewById(R.id.btnNavigate); btn.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { String url = editText.getText().toString(); Intent intent = new Intent(Intent.ACTION_VIEW, Uri.parse(url)); startActivity(intent); } });
- 16. Intent Filter:
- 18. Intent Filter: • decide the behavior of an intent. • -Intent about the navigation of one activity to another,that can be achieve by declaring intent filter. • -We can declare an Intent Filter for an Activity in manifest file. • - Intent filters specify the type of intents that an Activity, service or Broadcast receiver can respond to.
- 19. Syntax of Intent Filters: • <activity android:name=".MainActivity"> • <intent-filter • android:icon="@drawable/icon" android:label="@string/label" > • <action android:name="android.intent.action.MAIN" /> • <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> • </activity>
- 20. What are icons and labels • icon: This is displayed as icon for activity. You can check or save png image of name icon in drawable folder. android:icon="@drawable/icon" • • label: The label / title that appears at top in Toolbar of that particular Activity. You can check or edit label name by opening String XML file present inside Values folder android:label = "@string/label“ or android:label = "New Activity“ Just like icon attribute, if you have not declared any label for your activity then it will be same as your parent activity
- 21. • Elements In Intent Filter: • There are following three elements in an intent filter: • 1.Action • 2.Data • 3.Category
- 22. Multipurpose Internet Mail Extensions
- 24. Action
- 25. Examples
- 26. Data
- 28. Activity Lifecycle: • Activity is a screen that user interact with. Every Activity in android has lifecycle like created, started, resumed, paused, stopped or destroyed. These different states are known as Activity Lifecycle.
- 29. • onCreate() – Called when the activity is first created • onStart() – Called just after it’s creation or by restart method after onStop(). Here Activity start becoming visible to user • onResume() – Called when Activity is visible to user and user can interact with it • onPause() – Called when Activity content is not visible because user resume previous activity • onStop() – Called when activity is not visible to user because some other activity takes place of it • onRestart() – Called when user comes on screen or resume the activity which was stopped • onDestroy – Called when Activity is not in background
- 31. Broadcast Receiver • Broadcast Receiver is a component which will allow android system or other apps to deliver events to the app like sending a low battery message or screen turned off message to the app. The apps can also initiate broadcasts to let other apps know that required data available in a device to use it. • Generally, we use Intents to deliver broadcast events to other apps and Broadcast Receivers use status bar notifications to let user know that broadcast event occurs. • is implemented as a subclass of Broadcast Receiver and each broadcast is delivered as an Intent object.
- 32. Two important steps to make BroadcastReceiver: • Registering Broadcast Receiver • • Creating the Broadcast Receiver
- 33. • A broadcast receiver is implemented as a subclass of BroadcastReceiver class and overriding the onReceive() method where each message is received as a Intent object parameter. • Example- public class MyReceiver extends BroadcastReceiver { public void onReceive(Context context, Intent intent) { Toast.makeText(context, "Intent Detected.", Toast.LENGTH_LONG).show(); } }
- 34. System generated events are: • android.intent.action.BATTERY_CHANGED • • android.intent.action.BATTERY_LOW • • android.intent.action.BATTERY_OKAY • • android.intent.action.BOOT_COMPLETED • • android.intent.action.BUG_REPORT • • android.intent.action.CALL • • android.intent.action.CALL_BUTTON • • android.intent.action.DATE_CHANGED • • android.intent.action.REBOOT
- 38. Create Button click Event
- 39. Registered this button to event Go to your xml file
- 40. Create intent instance , set action , set flag, send intent
- 41. Create another app for Receiving
- 42. Receiver app is not registered yet
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