http://www.vogella.com/articles/AndroidIntent/article.html



Lars Vogel

Version 3.3

16.08.2013

Revision History
Revision 0.120.07.2010Lars
Vogel
Created
Revision 0.2 - 3.319.07.2010 - 16.08.2013Lars
Vogel
bug fixes and enhancements

Using Intents in Android

This tutorials describes the usage of intents to communicate between Android components. It is based on Eclipse 4.3, Java 1.6 and Android 4.3.


1. Intents and intent filter

1.1. What are intents?

Intents are asynchronous messages which allow application components to request functionality from other Android components. Intents allow you to interact with components from the own and other applications. For example an activity can start an external activity for taking a picture.

Intents are objects of the android.content.Intent type. Your code can send them to the Android system defining the components you are targeting. For example via the startActivity() method you can define that the intent should be used to start an activity.

An intent can contain data via a Bundle. This data can be used by the receiving component.

1.2. Starting activities

To start an activity use the method startActivity(intent). This method is defined on the Context object whichActivity extends.

The following code demonstrates how you can start another activity via an intent.

# Start the activity connect to the
# specified class

Intent i = new Intent(this, ActivityTwo.class);
startActivity(i); 

1.3. Sub-activities

Activities which are started by other Android activities are called sub-activities. This wording makes it easier to describe which activity is meant.

1.4. Starting services

You can also start service via intents. Use the startService(Intent) method call for that.

1.5. Intent filter

Intents are used to signal to the Android system that a certain event has occurred. Intents often describes the action which should be performed and provide data on which such an action should be done. For example your application can start via an intent a browser component for a certain URL. This is demonstrated by the following example.

String url = "http://www.vogella.com";
Intent i = new Intent(Intent.ACTION_VIEW);
i.setData(Uri.parse(url));
startActivity(i); 

But how does the Android system identify the components which can react to a certain intent?

For this the concept of an intent filter is used. An intent filter specifies the types of intents to which that an activity , service, or broadcast receiver can respond to. It declares therefore the capabilities of a component.

Android components register intent filters either staticially in the AndroidManifest.xml or in case of a broadcast receiver also dynamically via code. An intent filter is defined by its category, action and data filters. It can also contain additional metadata.

If an intent is send to the Android system, the Android platform runs, using the data included in the Intent object, an receiver determination. In this it determines the components which are registered for the data of the intent. If several components have registered for the same intent filter the user can decide which component should be started.

2. Intents types

2.1. Different types of intents

Android supports explicit and implicit Intents.

An application can define the target component directly in the intent (explicit intent) or ask the Android system to evaluate registered components based on the intent data (implicit intents).

2.2. Explicit Intents

Explicit intents explicitly defines the component which should be called by the Android system, by using the Java class as identifier.

The following shows how to create an explicit intents and send it to the Android system. If that class represents anactivity Intent the Android system start it.

Intent i = new Intent(this, ActivityTwo.class);
i.putExtra("Value1", "This value one for ActivityTwo ");
i.putExtra("Value2", "This value two ActivityTwo"); 

s Explicit intents are typically used within on application as the classes in an application are controlled by the application developer.

2.3. Implicit Intents

Implicit intents specify the action which should be performed and optionally data which provides data for the action.

For example the following tells the Android system to view a webpage. All installed web browsers should be registered to the corresponding intent data via an intent filter.

Intent i = new Intent(Intent.ACTION_VIEW, Uri.parse("http://www.vogella.com"));
startActivity(i); 

If an explicit intent is send to the Android system, it searches for all components which are registered for the specific action and the fitting data type.

If only one component is found, Android starts this component directly. If several components are identifier by the Android system, the user will get an selection dialog and can decide which component should be used for the intent.

3. Data transfer between activities

3.1. Data transfer to the target component

An intent contains the action and optionally additional data. The component which creates the Intent can add data to it via the overloaded putExtra() method. Extras are key/value pairs; the key is always a String. As value you can use the primitive data types (int, float,..) plus objects of type String, Bundle, Parceable and Serializable.

The receiving component can access this information via the getAction() and getData() methods on the Intentobject. This Intent object can be retrieved via the getIntent() method.

The component which receives the intent can use the getIntent().getExtras() method call to get the extra data.

Bundle extras = getIntent().getExtras();
if (extras == null) {
    return;
    }
// Get data via the key
String value1 = extras.getString(Intent.EXTRA_TEXT);
if (value1 != null) {
  // do something with the data
} 

3.2. Example: Using the share intent

Lots of Android applications allow you to share some data with other people, e.g. the Facebook, G+, Gmail and Twitter application. You can send data to one of this components. The following code snippet demonstrates that.

Intent intent = new Intent(Intent.ACTION_SEND);
intent.setType("text/plain");
intent.putExtra(android.content.Intent.EXTRA_TEXT, "News for you!");
startActivity(intent); 

3.3. Retrieving result data from a sub-activity

An activity can be closed via the back button on the phone. In this case the finish() method is performed. If the activity was started with the startActivity(Intent) method call, the caller requires no result or feedback from the activity which now is closed.

If you start the activity with the startActivityForResult() method call, you expect feedback from the sub-activity. Once the sub-activity ends the onActivityResult() method on the sub-activity is called and you can perform actions based on the result.

In the startActivityForResult() method call you can specify a result code to determine which activity you started. This result code is returned to you. The started activity can also set a result code which the caller can use to determine if the activity was canceled or not.

startActivity with result

startActivity with result

The sub-activity uses the finish() method to create a new intent and to put data into it. It also set an result via thesetResult() method call.

The following example code demonstrates how to trigger and intent with the startActivityForResult() method.

public void onClick(View view) {
  Intent i = new Intent(this, ActivityTwo.class);
  i.putExtra("Value1", "This value one for ActivityTwo ");
  i.putExtra("Value2", "This value two ActivityTwo");
  // Set the request code to any code you like, you can identify the
  // callback via this code
  startActivityForResult(i, REQUEST_CODE);
} 

If you use the startActivityForResult() method then the started activity is called a Sub-Activity.

If the sub-activity is finished it can send data back to its caller via Intent. This is done in the finish() method.

@Override
public void finish() {
  // Prepare data intent 
  Intent data = new Intent();
  data.putExtra("returnKey1", "Swinging on a star. ");
  data.putExtra("returnKey2", "You could be better then you are. ");
  // Activity finished ok, return the data
  setResult(RESULT_OK, data);
  super.finish();
} 

Once the sub-activity finishes, the onActivityResult() method in the calling activity is be called.

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
  if (resultCode == RESULT_OK && requestCode == REQUEST_CODE) {
    if (data.hasExtra("returnKey1")) {
      Toast.makeText(this, data.getExtras().getString("returnKey1"),
        Toast.LENGTH_SHORT).show();
    }
  }
} 

4. Defining intent filters

4.1. Defining intent filter

You can register your own components via intent filters. If a component does not define one, it can only be called by explicit intent. This chapter gives some example for registering a component for an intent. The key for this registration is that your component registers for the correct action, mime-type and specifies the correct meta-data.

4.2. Example: Register an activity as Browser

The following code will register an Activity for the Intent which is triggered when someone wants to open a webpage.

<activity android:name=".BrowserActivitiy" 
          android:label="@string/app_name">
  <intent-filter>
     <action android:name="android.intent.action.VIEW" />
     <category android:name="android.intent.category.DEFAULT" />
     <data android:scheme="http"/> 
  </intent-filter>
</activity> 

4.3. Example: Register an activity for the share intent

The following example registers an activity for the ACTION_SEND intent. It declares itself only relevant for the text/plainmime type.

<activity
  android:name=".ActivityTest"
    android:label="@string/app_name" >
    <intent-filter>
      <action android:name="android.intent.action.SEND" />
      
      <category android:name="android.intent.category.DEFAULT" />

      <data android:mimeType="text/plain" />
    
    </intent-filter>

</activity> 

If a component does not define an Intent filter, it can only be called by explicit Intents.

5. Intents as event triggers

Intents can also be used to send broadcast messages into the Android system. BroadcastReceivers can register to event and will get notified if such an event is triggered.

Your application can register to system events, e.g. a new email has arrived, system boot is complete or a phone call is received and react accordingly.

As said earlier, since Android version 3.1 the Android system will per default exclude all BroadcastReceiver from receiving Intents if the corresponding application has never been started by the user or if the user explicitly stopped the application via the Android menu (in Manage Application).

6. Determine valid intent receivers

Sometimes you want to determine if an component has registered for an intent. . For example you want to check if a certain intent receiver is available and in case a component is available you enable a functionality in your application.

This check can be done via the PackageManager class.

The following example code checks if a component has registered for a certain intent. Construct your Intent as you desired to trigger it and pass it to the following method.

public static boolean isIntentAvailable(Context ctx, Intent intent) {
   final PackageManager mgr = ctx.getPackageManager();
   List<ResolveInfo> list =
      mgr.queryIntentActivities(intent, 
         PackageManager.MATCH_DEFAULT_ONLY);
   return list.size() > 0;
} 

Based on the result you can adjust your application. For example you could disable or hide certain menu items.

7. Prerequisites for this tutorial

The following assumes that you have already basic knowledge in Android development. Please check the Android development tutorial to learn the basics.

8. Exercise: Starting activities

8.1. Target of this exercise

The following exercise demonstrates how to use an explicit intent to start a sub-activity and how to send data to it.

This is the first part of an exercise continued in Section 9.1, “Target of this exercise”. The final solution can be found in Section 10, “Solution: Using intents”.

8.2. Create project and main layout

Create a new Android project called com.vogella.android.intent.explicit with an activity called MainActivity.

Change the layout of the first activity to the following.

<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"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".MainActivity" >

    <EditText
        android:id="@+id/inputforintent"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:minHeight="60dip"
        android:text="First Activity"
        android:textSize="20sp" >
    </EditText>

    <Button
        android:id="@+id/startintent"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/inputforintent"
        android:layout_below="@+id/inputforintent"
        android:onClick="onClick"
        android:text="Calling an intent" />

</RelativeLayout> 

8.3. Create new layout file

Create a new layout called activity_result.xml which will be used in your second activity.

To create a new layout file select your project, right click on it and select File → New → Other... → Android →Android XML File and select the Layout option.

Enter activity_result.xml as file name and press the Finish button. Change your layout so that it is similar to the following XML file.

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <TextView
        android:id="@+id/displayintentextra"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Input"
        android:textAppearance="?android:attr/textAppearanceLarge" />

    <EditText
        android:id="@+id/returnValue"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" >

        <requestFocus />
    </EditText>

</LinearLayout> 

8.4. Create new activity

Add a new activity to the AndroidManifest.xml file.

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.vogella.android.first"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk android:minSdkVersion="14" />

    <application
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name" >
        <activity
            android:label="@string/app_name"
            android:name=".MainActivity" >
            <intent-filter >
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <activity
            android:label="Result Activity"
            android:name=".ResultActivity" >
        </activity>
    </application>

</manifest> 

Create the corresponding ResultActivity class based on the following example code.

package com.vogella.android.intent.explicit;

import android.app.Activity;
import android.os.Bundle;

public class ResultActivity extends Activity {

  @Override
  public void onCreate(Bundle bundle) {
    super.onCreate(bundle);
    setContentView(R.layout.activity_result);
  }
} 

This new activity will be started via the first activity, hence it is called a sub-activity.

8.5. Start sub-activity

Start the sub-activity via a button click from the MainActivity class. The following code gives some pointers how to solve this.

package com.vogella.android.intent.explicit;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;

public class MainActivity extends Activity {

  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
  }

  public void onClick(View view) {
    EditText text = (EditText) findViewById(R.id.inputforintent);
    // used later
    String value = text.getText().toString();
    // TODO 1 create new explicit Intent
    // based on "ResultActivity.class"

    // TODO 2 start second Activity with
    // startActivity(intent);
  }

} 

Solve the TODO's in the source code so that the ResultActivity activity is started from the onClick() method.

Once you finished this part of the exercise, start your application an ensure that you can start the second activity.

8.6. Send data to ResultActivity

The MainActivity class should pass the value of the EditText view to the sub-activity. For this use theputExtra("yourKey", string) on the Intent object.

8.7. Get intent data in the ResultActivity

In your ResultActivity sub-activity get the Bundle with the intent data via the getIntent().getExtras()) method call.

Get the value of the passed extra with the getExtra("yourKey") method on the bundle object which you got with thegetExtras() call.

This value should be placed in the TextView with the displayintentextra ID.

9. Exercise: Receiving data from sub-activities

9.1. Target of this exercise

This is the second part of an exercise which started in Section 8.1, “Target of this exercise”. An example solution for the activity can be found in Section 10, “Solution: Using intents”.

Continue to use the com.vogella.android.intent.explicit project.

In the following exercise you transfer data back from your sub-activity second to the (MainActivity once the user selects the Back button.

9.2. Return data from ResultActivity

Add the implementation of the finish() method to the ResultActivity class.

@Override
public void finish() {
    
  // TODO 1 create new Intent 
  // Intent intent = new Intent();
    
  // TODO 2 read the data of the EditText field
  // with the id returnValue
  
  // TODO 3 put the text from EditText
  // as String extra into the intent
  // use editText.getText().toString();
    
  // TODO 4 use setResult(RESULT_OK, intent); 
  // to return the Intent to the application
  
  super.finish();
} 

Solve all TODOs.

9.3. Evaluate the return data in MainActivity

Use in MainActivity the startActivityForResult() method to start the sub-activity. This allows you to use theonActivityResult() method to receive data from the sub-activity. Extract the extra with the received bundle.

Show a Toast with the extra data to validate that you correctly received it. The following code contains some pointer how to solve that.

package com.vogella.android.intent.explicit;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;

public class MainActivity extends Activity {
  
  // constant to determine which sub-activity returns
  private static final int REQUEST_CODE = 10;

  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
  }

  public void onClick(View view) {
    EditText text = (EditText) findViewById(R.id.inputforintent);
    String string = text.getText().toString();
    Intent i = new Intent(this, ResultActivity.class);
    i.putExtra("yourkey", string);
    // TODO 2.. now use 
    // startActivityForResult(i, REQUEST_CODE);
  }

  // TODO 3 Implement this method
  // assumes that "returnkey" is used as key to return the result
  @Override
  protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    if (resultCode == RESULT_OK && requestCode == REQUEST_CODE) {
      if (data.hasExtra("returnkey")) {
        String result = data.getExtras().getString("returnkey");
        if (result != null && result.length() > 0) {
          Toast.makeText(this, result, Toast.LENGTH_SHORT).show();
        }
      }
    }
  }
} 

10. Solution: Using intents

10.1. Overview

After finishing the exercise in Section 9.1, “Target of this exercise” your activity coding should look similar to the following classes.

10.2. Activity code

package com.vogella.android.intent.explicit;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.widget.EditText;
import android.widget.TextView;

public class ResultActivity extends Activity {

  @Override
  public void onCreate(Bundle bundle) {
    super.onCreate(bundle);
    setContentView(R.layout.activity_result);
    Bundle extras = getIntent().getExtras();
    String inputString = extras.getString("yourkey");
    TextView view = (TextView) findViewById(R.id.displayintentextra);
    view.setText(inputString);
  }

  @Override
  public void finish() {
    Intent intent = new Intent();
    EditText editText= (EditText) findViewById(R.id.returnValue);
    String string = editText.getText().toString();
    intent.putExtra("returnkey", string);
    setResult(RESULT_OK, intent);
    super.finish();
  }
} 

package com.vogella.android.intent.explicit;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;
import android.widget.Toast;

public class MainActivity extends Activity {

  // constant to determine which sub-activity returns
  private static final int REQUEST_CODE = 10;

  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
  }


  public void onClick(View view) {
    EditText text = (EditText) findViewById(R.id.inputforintent);
    String string = text.getText().toString();
    Intent i = new Intent(this, ResultActivity.class);
    i.putExtra("yourkey", string);
    startActivityForResult(i, REQUEST_CODE);
  }

  @Override
  protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    if (resultCode == RESULT_OK && requestCode == REQUEST_CODE) {
      if (data.hasExtra("returnkey")) {
        String result = data.getExtras().getString("returnkey");
        if (result != null && result.length() > 0) {
          Toast.makeText(this, result, Toast.LENGTH_SHORT).show();
        }
      }
    }
  }
} 

11. Exercise: Using implicit intents

The following exercise demonstrates the usage of implicit intents to trigger activities in your Android system.

Create a new Android application called de.vogella.android.intent.implicit with an activity calledCallIntentsActivity.

In this example you use a Spinner view to select which intent is triggered. For the content of the Spinner you define static values.

Create the following intents.xml file in the res/values folder.

<resources>
    <string-array name="intents">
        <item>Open Browser</item>
        <item>Call Someone</item>
        <item>Dial</item>
        <item>Show Map</item>
        <item>Search on Map</item>
        <item>Take picture</item>
        <item>Show contacts</item>
        <item>Edit first contact</item>
    </string-array>
    
</resources> 

Change the layout file of the Activity to the following.

<?xml version="1.0" encoding="utf-8"?>
<GridLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:alignmentMode="alignBounds"
    android:columnCount="1" >

      <Spinner
        android:id="@+id/spinner"
        android:layout_gravity="fill_horizontal"
        android:drawSelectorOnTop="true"
        >
      </Spinner>
    
    <Button
        android:id="@+id/trigger"
        android:onClick="onClick"
        android:text="Trigger Intent">
    </Button>

  
</GridLayout> 

To be able to use certain intents you need to register for the required permission in your AndroidManifest.xml file. Ensure that your AndroidManifest.xml contain the permissions from the followng listing.

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="de.vogella.android.intent.implicit"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk android:minSdkVersion="15" />

    <uses-permission android:name="android.permission.CALL_PRIVILEGED" >
    </uses-permission>
    <uses-permission android:name="android.permission.CALL_PHONE" >
    </uses-permission>
    <uses-permission android:name="android.permission.CAMERA" >
    </uses-permission>
    <uses-permission android:name="android.permission.READ_CONTACTS" >
    </uses-permission>
    <uses-permission android:name="android.permission.INTERNET"/>

    <application
        android:icon="@drawable/icon"
        android:label="@string/app_name" >
        <activity
            android:name=".CallIntentsActivity"
            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> 

Change your activity class to the following code.

package de.vogella.android.intent.implicit;

import android.app.Activity;
import android.content.Intent;
import android.net.Uri;
import android.os.Bundle;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.Spinner;
import android.widget.Toast;

public class CallIntentsActivity extends Activity {
  private Spinner spinner;

  
/** Called when the activity is first created. */
@Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); spinner = (Spinner) findViewById(R.id.spinner); ArrayAdapter adapter = ArrayAdapter.createFromResource(this, R.array.intents, android.R.layout.simple_spinner_item); adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item); spinner.setAdapter(adapter); } public void onClick(View view) { int position = spinner.getSelectedItemPosition(); Intent intent = null; switch (position) { case 0: intent = new Intent(Intent.ACTION_VIEW, Uri.parse("http://www.vogella.com")); break; case 1: intent = new Intent(Intent.ACTION_CALL, Uri.parse("tel:(+49)12345789")); break; case 2: intent = new Intent(Intent.ACTION_DIAL, Uri.parse("tel:(+49)12345789")); startActivity(intent); break; case 3: intent = new Intent(Intent.ACTION_VIEW, Uri.parse("geo:50.123,7.1434?z=19")); break; case 4: intent = new Intent(Intent.ACTION_VIEW, Uri.parse("geo:0,0?q=query")); break; case 5: intent = new Intent("android.media.action.IMAGE_CAPTURE"); break; case 6: intent = new Intent(Intent.ACTION_VIEW, Uri.parse("content://contacts/people/")); break; case 7: intent = new Intent(Intent.ACTION_EDIT, Uri.parse("content://contacts/people/1")); break; } if (intent != null) { startActivity(intent); } } @Override public void onActivityResult(int requestCode, int resultCode, Intent data) { if (resultCode == Activity.RESULT_OK && requestCode == 0) { String result = data.toURI(); Toast.makeText(this, result, Toast.LENGTH_LONG); } } }

If you start your application you see an list of buttons and if you press one of the buttons, your defined activities are started.

Note

Note that you didn't specify any receiving application only the thing that should be done. This allows you to define loosely coupled tasks which use components of different applications.

12. Exercise: Register an intent filter for http requests

In the following exercise you register an activity as browser. This means that if an intent is triggered what someone wants to view an URL starting with http your activity will also be available to process this intent.

The example activity downloads the HTML source of this page and display this in a TextView.

Create the Android project called de.vogella.android.intent.browserfilter with the activity called BrowserActivity.

Register your activity to Intent.Action_VIEW action and the scheme "http" via the following changes in yourAndroidManifest.xml file The manifest also declares the permission to access the Internet.

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="de.vogella.android.intent.browserfilter"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk android:minSdkVersion="15" />

    <uses-permission android:name="android.permission.INTERNET" >
    </uses-permission>

    <application
        android:icon="@drawable/icon"
        android:label="@string/app_name" >
        <activity
            android:name=".BrowserActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.VIEW" />

                <category android:name="android.intent.category.DEFAULT" />

                <data android:scheme="http" />
            </intent-filter>
        </activity>
    </application>

</manifest> 

Change corresponding layout file to the following.

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    >
<TextView  
    android:layout_width="match_parent" 
    android:layout_height="wrap_content" 
    android:id="@+id/textView"/>
</LinearLayout> 

Change your activity class to the following code.

package de.vogella.android.intent.browserfilter;

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.URL;

import android.app.Activity;
import android.content.Intent;
import android.net.Uri;
import android.os.Bundle;
import android.os.StrictMode;
import android.widget.TextView;

public class BrowserActivity extends Activity {
  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    // To keep this example simple, we allow network access
    // in the user interface thread
    StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder()
        .permitAll().build();
    StrictMode.setThreadPolicy(policy);

    setContentView(R.layout.main);
    Intent intent = getIntent();
    TextView text = (TextView) findViewById(R.id.textView);
    // To get the action of the intent use
    String action = intent.getAction();
    if (!action.equals(Intent.ACTION_VIEW)) {
      throw new RuntimeException("Should not happen");
    }
    // To get the data use
    Uri data = intent.getData();
    URL url;
    try {
      url = new URL(data.getScheme(), data.getHost(), data.getPath());
      BufferedReader rd = new BufferedReader(new InputStreamReader(url.openStream()));
      String line = "";
      while ((line = rd.readLine()) != null) {
        text.append(line);
      }

    } catch (Exception e) {
      e.printStackTrace();
    }

  }
} 

Install your application. If you now trigger an intent to open an URL your should be able to select your own component. You can for example trigger this intent via the example from the implicit tutorials.

If you select you component the HTML code is loaded into your text view.

xbrowserfilter10.png.pagespeed.ic.aVcsLJWoS7.png

xbrowserfilter20.png.pagespeed.ic.xE8tzeV6HN.png

13. Exercise: picking an image via an intent

The following example shows how to pick an image from any registered photo application on Android via an intent.

Create a new Android project called de.vogella.android.imagepick with one activity called ImagePickActivity.

Change the activity_main.xml layout file to the following.

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <Button
        android:id="@+id/button1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:onClick="pickImage"
        android:text="Button" >
    </Button>

    <ImageView
        android:id="@+id/result"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:src="@drawable/icon" >
    </ImageView>

</LinearLayout> 

Change your activity class according to the following coding.

package de.vogella.android.imagepick;

import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;

import android.app.Activity;
import android.content.Intent;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Bundle;
import android.view.View;
import android.widget.ImageView;

public class ImagePickActivity extends Activity {
  private static final int REQUEST_CODE = 1;
  private Bitmap bitmap;
  private ImageView imageView;

  
/** Called when the activity is first created. */
@Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); imageView = (ImageView) findViewById(R.id.result); } public void pickImage(View View) { Intent intent = new Intent(); intent.setType("image/*"); intent.setAction(Intent.ACTION_GET_CONTENT); intent.addCategory(Intent.CATEGORY_OPENABLE); startActivityForResult(intent, REQUEST_CODE); } @Override protected void onActivityResult(int requestCode, int resultCode, Intent data) { InputStream stream = null; if (requestCode == REQUEST_CODE && resultCode == Activity.RESULT_OK) try { // recyle unused bitmaps if (bitmap != null) { bitmap.recycle(); } stream = getContentResolver().openInputStream(data.getData()); bitmap = BitmapFactory.decodeStream(stream); imageView.setImageBitmap(bitmap); } catch (FileNotFoundException e) { e.printStackTrace(); } finally { if (stream != null) try { stream.close(); } catch (IOException e) { e.printStackTrace(); } } } }

If you run this application you can select an image from your image library on your Android phone and assign it to your ImageView.

14. Thank you

Please help me to support this article:

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15. Questions and Discussion

If you find errors in this tutorial, please notify me (see the top of the page). Please note that due to the high volume of feedback I receive, I cannot answer questions to your implementation. Ensure you have read the vogella FAQ as I don't respond to questions already answered there.

16. Links and Literature

16.1. Source Code

Source Code of Examples

16.3. vogella Resources

vogella Training Android and Eclipse Training from the vogella team

Android Tutorial Introduction to Android Programming

GWT Tutorial Program in Java, compile to JavaScript and HTML

Eclipse RCP Tutorial Create native applications in Java

JUnit Tutorial Test your application

Git Tutorial Put all your files in a distributed version control system