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Android Explicit Intent Example

By Arvind Rai, October 10, 2014
Intent in Android supports communication between app component. An Intent can start an activity, service and can deliver a broadcast. There are two types of Intent: Explicit and Implicit. In this page we will understand how to use Explicit Intent in our android application. Explicit Intent communicates an activity referring by fully qualified class name. Generally we use Explicit Intent to call an activity because we know the class name of activity which we are calling.
To run the Explicit Intent Demo, we are creating an app to add two number. There will be two UI, one to get input from user and second to display result. Now find the description in detail. We are using Eclipse IDE to create the demo.

Create Android Layout using TextView, EditText and Button

We are creating two screen. First screen will take two number input from user. After click on Add button, second screen will open. For the first screen we are creating LinearLayout using TextView, EditText and Button tags.
1. TextView defines text message.
2. EditText creates the text field.
3. Button will create a button to listen click event.
All the above tags uses attributes like
1. android:id : Defines the id by which it will be fetched in Activity class.
2. android:layout_width: Defines the width of TextView, EditText and Button
3. android:layout_height : Defines the height of TextView, EditText and Button
Now find the first layout which is creating two text field and a button.
pageone.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >
    <TextView
        android:id="@+id/firstNumText"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="First Number"
        android:textAppearance="?android:attr/textAppearanceSmall" />
    <EditText
        android:id="@+id/firstNum"
        android:layout_width="150dp"
        android:layout_height="40dp"
        android:ems="5">
    </EditText>
    <TextView
        android:id="@+id/secondNumText"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Second Number"
        android:textAppearance="?android:attr/textAppearanceSmall" />
    <EditText
        android:id="@+id/secondNum"
        android:layout_width="150dp"
        android:layout_height="40dp"
        android:ems="5" />
    <Button
        android:id="@+id/addButton"
        android:layout_width="50dp"
        android:layout_height="45dp"
        android:text="Add" />
</LinearLayout> 
First UI will be displayed as below. We can enter two numbers and Add button to click.
Android Explicit Intent Example
Now find the second layout. In this layout there is only one TextView which will show the result.
result.xml
<?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/resultView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textAppearance="?android:attr/textAppearanceLarge" android:text="TEXT" />
</LinearLayout> 
Second UI will be as below.
Android Explicit Intent Example
After clicking add button, second page will open as above.


Create Android Activity using Intent Class

In AndroidManifest.xml, we are defining two Activity class. First one is ExplicitIntentActivity.java and second one is ResultActivity.java. Both Activity class will extend android.app.Activity. Inside onCreate method, we have created Intent Object. Find the first activity class ExplicitIntentActivity.java. This will derive OnClickListener to listen Add button. Explicit Intent will be declared as below.
Intent explicitIntent = new Intent(ExplicitIntentActivity.this,	ResultActivity.class);
explicitIntent.putExtra(key, value);
startActivity(explicitIntent); 
Now find the first activity class.
ExplicitIntentActivity.java
package com.cp.android;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
public class ExplicitIntentActivity extends Activity {
	EditText firstNum;
	EditText secondNum;
	Button add; 
	int sum;
	@Override
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.pageone);
		firstNum = (EditText) findViewById(R.id.firstNum);
		secondNum = (EditText) findViewById(R.id.secondNum);
		add = (Button) findViewById(R.id.addButton);
		add.setOnClickListener(new AddButtonClickHandler());
	}
	public class AddButtonClickHandler implements OnClickListener {
		public void onClick(View view) {
			int num1 = Integer.parseInt(firstNum.getText().toString());
			int num2 = Integer.parseInt(secondNum.getText().toString());
			Intent explicitIntent = new Intent(ExplicitIntentActivity.this,
					ResultActivity.class);
			explicitIntent.putExtra("SUM", num1 + "+" + num2 + "=" + (num1 + num2));
			startActivity(explicitIntent);
		}
	}
} 
In the second activity class onCreate method has been declared and intent object has been initialized as below.
Intent intent = getIntent();
String sum = (String) intent.getSerializableExtra("SUM");
result.setText(sum); 
Now find the second activity class.
ResultActivity.java
package com.cp.android;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.widget.TextView;
public class ResultActivity extends Activity {
	@Override
	public void onCreate(Bundle savedInstanceState) {
		TextView result;
		super.onCreate(savedInstanceState);
		setContentView(R.layout.result);
		result = (TextView) findViewById(R.id.resultView);
		Intent intent = getIntent();
		String sum = (String) intent.getSerializableExtra("SUM");
		result.setText(sum);
	}
} 

Configure AndroidManifest.xml for the Activity class

Find the AndroidManifest.xml which configures both Activity class.
AndroidManifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.cp.android"
    android:versionCode="1"
    android:versionName="1.0" >
    <uses-sdk android:minSdkVersion="10" />
    <application
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name" >
        <activity
            android:name="com.cp.android.ExplicitIntentActivity"
            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.cp.android.ResultActivity"
            android:label="@string/app_name" >
        </activity>
    </application>
</manifest> 
Now we are done. We can run our application. Find the link to download the complete source code and APK file to run app directly.

Download Source Code

Download APK file

POSTED BY
ARVIND RAI
ARVIND RAI
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