AndroidIntents
1323 views.Android Intent is the message that is passed between components such as activities, content providers, broadcast receivers, services etc.
It is generally used with startActivity() method to invoke activity, broadcast receivers etc.
The dictionary meaning of intent is intention or purpose. So, it can be described as the intention to do action.
The LabeledIntent is the subclass of android.content.Intent class.
Android intents are mainly used to:
- Start the service
- Launch an activity
- Display a web page
- Display a list of contacts
- Broadcast a message
- Dial a phone call etc.
There are two types of intents in android: implicit and explicit.
1) Implicit Intent
Implicit Intent doesn’t specifiy the component. In such case, intent provides information of available components provided by the system that is to be invoked.
For example, you may write the following code to view the webpage.
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Intent intent=new Intent(Intent.ACTION_VIEW); intent.setData(Uri.parse("http://androindian.com/")); startActivity(intent); |
Program for Implicit Intent
Activity_main.xml
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<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="${relativePackage}.${activityClass}" > <TextView android:id="@+id/textView1" android:layout_width="fill_parent" android:layout_height="wrap_content" android:text="Implicit Intent Example" android:gravity="center"/> <Button android:id="@+id/button1" android:layout_width="fill_parent" android:layout_height="wrap_content" android:layout_alignParentLeft="true" android:layout_below="@+id/textView1" android:layout_marginTop="137dp" android:text="Click me" /> </RelativeLayout> |
ActivityMain.Java
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package com.raj.implicitintent; import android.app.Activity; import android.content.Intent; import android.net.Uri; import android.os.Bundle; import android.view.Menu; import android.view.MenuItem; import android.view.View; import android.view.View.OnClickListener; import android.widget.Button; public class MainActivity extends Activity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); Button b=(Button) findViewById(R.id.button1); b.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { // TODO Auto-generated method stub String url = "http://androindian.com/"; Intent i = new Intent(Intent.ACTION_VIEW); i.setData(Uri.parse(url)); startActivity(i); } }); } } |
AndroidManifest.xml
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<?xml version="1.0" encoding="utf-8"?> <manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.raj.implicitintent" android:versionCode="1" android:versionName="1.0" > <uses-sdk android:minSdkVersion="8" android:targetSdkVersion="21" /> <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=".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> |
2) Explicit Intent
Explicit Intent specifies the component. In such case, intent provides the external class to be invoked.
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Intent i = new Intent(getApplicationContext(), ActivityTwo.class); startActivity(i); |
To get the full code of explicit intent, visit the next page
Program for Explicit Intents
Activity _Main.xml
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<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="${relativePackage}.${activityClass}" > <TextView android:id="@+id/textView1" android:layout_width="fill_parent" android:layout_height="wrap_content" android:text="Explicit Intent Example" android:gravity="center" /> <Button android:id="@+id/button1" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignParentLeft="true" android:layout_alignParentRight="true" android:layout_below="@+id/textView1" android:layout_marginTop="88dp" android:text="Button" /> </RelativeLayout> |
MainActivity.Java
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package com.raj.explicitintent; import android.app.Activity; import android.content.Intent; import android.os.Bundle; import android.view.Menu; import android.view.MenuItem; import android.view.View; import android.view.View.OnClickListener; import android.widget.Button; public class MainActivity extends Activity { Button bt; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); bt=(Button) findViewById(R.id.button1); bt.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { // TODO Auto-generated method stub Intent intent=new Intent(getApplicationContext(), Second.class); startActivity(intent); } }); } } |
Second_Activity.xml
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<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="${relativePackage}.${activityClass}" > <TextView android:layout_width="fill_parent" android:layout_height="wrap_content" android:text="Hi Mr. Raj...................Welcome to SEcond Activity" android:textSize="20sp" android:gravity="center"/> |
SecondActivity.java
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package com.raj.explicitintent; import android.app.Activity; import android.os.Bundle; import android.view.Menu; import android.view.MenuItem; public class Second extends Activity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_second); } } |
Android Manifest.xml
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<?xml version="1.0" encoding="utf-8"?> <manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.raj.explicitintent" android:versionCode="1" android:versionName="1.0" > <uses-sdk android:minSdkVersion="8" android:targetSdkVersion="21" /> <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> <activity android:name=".Second" android:label="@string/title_activity_second" > </activity> </application> </manifest> |
