Using Explicit Intent to send Data from one screen to another

In this example, we will be see how to use an Explicit Intent to send data from one screen to annother(Inter Activity Data Transfer)

Steps to develop this can be summarized below -

• Make a new project with Empty Activity.
• Make a button in the layout to fire(start) an explicit intent.
• Write the calling method for button.
• Inside the method create an intent object and provide a data(string)to it with putExtra method
• Prepare another empty activity with a button and Edit Text in the layout
• In the onCreate method of second activity, prepare a bundle object to receive the incoming intent
• Write a method for the button in second activity which fetches the data from the edit text and supplies it to the intent
• Fire the intent from the second activity towards the third activity
• Prepare another activity - third activity - to receive the intent from the second activity
• Similar code is written for third activity as well where the user can go to first activity by clicking the button
• Everytime user reaches an activity , the data from previous activity is displayed to them

Used Concepts & Used Version:

• compileSdkVersion 25
• buildToolsVersion "24.0.2"
• Explicit Intent
This is the type of intent where another activity is called by name. All activities must be defined in Android Manifest(AndroidManifest.xml). To pass data to another activity, we use putExtra to pass value. In this method, parameters are name and value. This is like a hash map of java.
Intent i2 = new Intent(this, TheDarkKnightRises.class);
startActivity(i2);
i2.putExtra("msg2",message2);
To retrive value in destination activity, the reference of calling intent is taken by calling getIntent method and value is obtained by giving reference to name that was placed in putExtra.

Now, let us begin the development...

1.BatmanBegins.class (First Activity)

This is going to be our launcher activity for the app. We will have a textview and a button in this activity. The button takes the user to the next screen which is TheDarkKnight.class activity. We use explicit intent to make this happen. In the given code below, we make a object - i1 - of the Intent class. Two parameters are provided to the Intent constructor - "msg": a key and "I liked Batman Begins": a String(data). We use 'putextra method for this.' Finally the intent is fired by calling startActivity(i1) method.

package sisoft.in.batman; import android.content.Intent; import android.support.v7.app.AppCompatActivity; import android.os.Bundle; import android.view.View; import android.widget.EditText; public class BatmanBegins extends AppCompatActivity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_batman_begins); } public void intent1(View v) { Intent i1 = new Intent(this, TheDarkKnight.class); i1.putExtra("msg","I liked Batman Begins!"); startActivity(i1); } public void onBackPressed(){ } }

2. Layout for BatmanBegins.class

Below is the layout for the same activity - BatmanBegins.class We have used a relative layout to hold a textview and a button. For the button , we havee used 'onClick' attribute. So whenever the user clicks on the button - intent1 method gets called which is defined in the respective class batmanbegins.class

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:id="@+id/activity_batman_begins" 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="sisoft.in.batman.BatmanBegins"> <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="You are watching Batman Begins!" android:id="@+id/tv1"/> <Button android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="Go to Activity2- The Dark Knight" android:onClick="intent1" android:layout_below="@+id/tv1" android:layout_marginTop="20dp"/> </RelativeLayout>

3. TheDarkKnight.class (Second Activity)

TheDarkKnight.class is the second activity presented to the user. As given in the code below, inside the onCreate method, there is a budle object created which is responsible for accepting the incoming intent using getIntent() and getextras() methods. From the intent, which is now referred to by the bundle object, we use getString() method to fetch the data which was present in the intent. This string is dsiplayed through a toast message. Also within the onCreate method, we have an EditText class'object prepared(et) which will be used to accept input from the user.

In this activity also, we will be using an intent object to take the user from this activity to third activity i.e. DarkKnightRises.class
We are going to pick data from the EditText using getText() and convert this text to a String using toString() method. After that the data is loaded onto the intent , like we did in the previous activity using the startActivity() method.

package sisoft.in.batman; import android.content.Intent; import android.support.v7.app.AppCompatActivity; import android.os.Bundle; import android.view.View; import android.widget.EditText; import android.widget.Toast; public class TheDarkKnight extends AppCompatActivity { EditText et; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_the_dark_knight); Bundle b = getIntent().getExtras(); String extra = b.getString("msg"); Toast.makeText(this,extra, Toast.LENGTH_SHORT).show(); et = (EditText)findViewById(R.id.et1); } public void intent2(View v) { String message2 = et.getText().toString(); Intent i2 = new Intent(this, TheDarkKnightRises.class); i2.putExtra("msg2",message2); startActivity(i2); finish(); } }

4. Layout for TheDarkKnight.class (Second Activity)

Below is the layout for the second class. We have a TextView,a Button and EditText. EditText,as discussed earlier gets us the users input and by clicking the Button, user is taken to the next activity. Here also, we have used the onClick attribute with the button to call the respective method(intent2() here)

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:id="@+id/activity_the_dark_knight" 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="sisoft.in.batman.TheDarkKnight"> <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="Welcome to The Dark Knight" android:id="@+id/tv2"/> <Button android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="Go to The Dark Knight Rises" android:onClick="intent2" android:layout_marginTop="20dp" android:id="@+id/btn3"/> <EditText android:layout_width="wrap_content" android:layout_height="wrap_content" android:id="@+id/et1" android:hint="Send a Message to Batman" android:layout_marginTop="20dp" android:layout_below="@+id/btn3"/> </RelativeLayout>

5. TheDarkKnightRises.class (Third Activity)

For the third activity, we follow the same pattern wherein we accept the intent in a bundle object and fetch data from it.The data is displayed in the toast message. Also, when the user clicks on the button in the layout, intent3() method gets called which fires another intent to take the user to the first activity.

package sisoft.in.batman; import android.content.Intent; import android.os.Bundle; import android.support.v7.app.AppCompatActivity; import android.view.View; import android.widget.Toast; public class TheDarkKnightRises extends AppCompatActivity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.thedarkknightrises); Bundle b1 = getIntent().getExtras(); String extra2 = b1.getString("msg2"); Toast.makeText(this,extra2, Toast.LENGTH_SHORT).show(); } public void intent3(View v) { Intent i3 = new Intent(this, BatmanBegins.class); startActivity(i3); finish(); } }

6. Layout for TheDarkKnightRises.class (Third Activity)

The below layout is for the third activity. Here we have used a lineat layout with vertical orientation. Also a TextView and a Button are placed inside the layout.

<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:layout_width="wrap_content" android:layout_height="wrap_content" android:text="Welcome to The Dark Knight rises" android:id="@+id/tv2"/> <Button android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="Go to The Batman Begins" android:onClick="intent3" android:layout_marginTop="20dp"/> </LinearLayout>

One important thing which is worth mentioning here is that all the intents are fired and a finish() method is also being called with them. This is to ensure that in case the user presses the back button in their phone, they are not taken back to the previous activity instance.

Below are the Screenshots for the output.