Pre-requisites:
- Android App Development Fundamentals for Beginners
- Guide to Install and Set up Android Studio
- Android | Starting with the first app/android project
- Android | Running your first Android app
This article aims to tell about the Implicit and Explicit intents and how to use them in an android app.
What is intent in Android?
The intent is a messaging object which passes between components like services, content providers, activities, etc. Normally startActivity() method is used for invoking any activity. Some of the general functions of intent are:
- Start service
- Launch Activity
- Display web page
- Display contact list
- Message broadcasting
Methods and their Description
| Methods | Description |
|---|---|
| Context.startActivity() | This is to launch a new activity or get an existing activity to be action. |
| Context.startService() | This is to start a new service or deliver instructions for an existing service. |
| Context.sendBroadcast() | This is to deliver the message to broadcast receivers. |
Intent Classification:
There are two types of intents in android
- Implicit Intent
- Explicit Intent
Implicit Intent
Using implicit Intent, components can’t be specified. An action to be performed is declared by implicit intent. Then android operating system will filter out components that will respond to the action. For Example,
In the above example, no component is specified, instead, an action is performed i.e. a webpage is going to be opened. As you type the name of your desired webpage and click on the ‘CLICK’ button. Your webpage is opened.
Step by Step Implementation
Creating an Android App to Open a Webpage Using Implicit Intent
Step 1: Create a New Project in Android Studio
To create a new project in Android Studio please refer to How to Create/Start a New Project in Android Studio. The code for that has been given in both Java and Kotlin Programming Language for Android. Create an XML file and Java File. Please refer to the pre-requisites to learn more about this step.
Step 2: Working with the XML Files
Next, go to the activity_main.xml file, which represents the UI of the project. Below is the code for the activity_main.xml file. Comments are added inside the code to understand the code in more detail.
Syntax:
android:id="@+id/id_name"
XML
<?xml version="1.0" encoding="utf-8"?><androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" tools:context=".MainActivity"> <EditText android:id="@+id/editText" android:layout_width="match_parent" android:layout_height="wrap_content" app:layout_constraintBottom_toBottomOf="parent" app:layout_constraintEnd_toEndOf="parent" app:layout_constraintStart_toStartOf="parent" app:layout_constraintTop_toTopOf="parent" /> <Button android:id="@+id/btn" android:text="Search" android:onClick="search" android:layout_width="wrap_content" android:layout_height="wrap_content" app:layout_constraintBottom_toBottomOf="parent" app:layout_constraintEnd_toEndOf="parent" app:layout_constraintStart_toStartOf="parent" app:layout_constraintTop_toBottomOf="@+id/editText" /></androidx.constraintlayout.widget.ConstraintLayout> |
Step 3: Working with the MainActivity File
Now, we will create the Backend of the App. For this, Open the MainActivity file and instantiate the component (Button) created in the XML file using the findViewById() method. This method binds the created object to the UI Components with the help of the assigned ID.
Syntax:
ComponentType object = (ComponentType) findViewById(R.id.IdOfTheComponent);
Java
import androidx.appcompat.app.AppCompatActivity;import android.content.Intent;import android.net.Uri;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) { EditText editText; Button button; super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); button = findViewById(R.id.btn); editText = (EditText) findViewById(R.id.editText); button.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View view) { String url=editText.getText().toString(); Intent intent = new Intent(Intent.ACTION_VIEW, Uri.parse(url)); startActivity(intent); } }); }} |
Kotlin
import android.content.Intentimport android.net.Uriimport android.os.Bundleimport android.widget.Buttonimport android.widget.EditTextimport androidx.appcompat.app.AppCompatActivityclass MainActivity : AppCompatActivity() { lateinit var editText: EditText override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_main) editText = findViewById(R.id.editText) } fun search() { val url = editText.text.toString() val urlIntent = Intent(Intent.ACTION_VIEW, Uri.parse(url)) startActivity(urlIntent) }} |
Explicit Intent
Using explicit intent any other component can be specified. In other words, the targeted component is specified by explicit intent. So only the specified target component will be invoked. For Example:
Explicit Intent Example
In the above example, There are two activities (FirstActivity, and SecondActivity). When you click on the ‘GO TO OTHER ACTIVITY’ button in the first activity, then you move to the second activity. When you click on the ‘GO TO HOME ACTIVITY’ button in the second activity, then you move to the first activity. This is getting done through Explicit Intent.
Step by Step Implementation
How to create an Android App to move to the next activity using Explicit Intent(with Example)
Step 1: Create a New Project in Android Studio
To create a new project in Android Studio please refer to How to Create/Start a New Project in Android Studio. The code for that has been given in both Java and Kotlin Programming Language for Android. Please refer to the pre-requisites to learn more about this step.
Step 2: Working with the activity_main.xml File
Next, go to the activity_main.xml file, which represents the UI of the project. Below is the code for the activity_main.xml file. Comments are added inside the code to understand the code in more detail.
Syntax:
android:id="@+id/id_name"
XML
<?xml version="1.0" encoding="utf-8"?><androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" tools:context=".MainActivity"> <TextView android:id="@+id/editText" android:layout_width="match_parent" android:layout_height="wrap_content" android:text="Welcome to GFG Home Screen" android:textAlignment="center" android:textSize="28sp" app:layout_constraintBottom_toBottomOf="parent" app:layout_constraintEnd_toEndOf="parent" app:layout_constraintHorizontal_bias="0.0" app:layout_constraintStart_toStartOf="parent" app:layout_constraintTop_toTopOf="parent" /> <Button android:id="@+id/btn1" android:text="Go to News Screen" android:onClick="newsScreen" android:layout_width="wrap_content" android:layout_height="wrap_content" app:layout_constraintBottom_toBottomOf="parent" app:layout_constraintEnd_toEndOf="parent" app:layout_constraintStart_toStartOf="parent" app:layout_constraintTop_toBottomOf="@+id/editText" /></androidx.constraintlayout.widget.ConstraintLayout> |
Step 3: Working with the MainActivity File
Now, we will create the Backend of the App. For this, Open the MainActivity file and instantiate the component (Button, TextView) created in the XML file using the findViewById() method. This method binds the created object to the UI Components with the help of the assigned ID.
Syntax:
ComponentType object = (ComponentType) findViewById(R.id.IdOfTheComponent); Intent i = new Intent(getApplicationContext(), <className>); startActivity(i);
Java
import androidx.appcompat.app.AppCompatActivity;import android.content.Intent;import android.os.Bundle;import android.view.View;public class MainActivity extends AppCompatActivity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); } public void newsScreen(View view) { Intent i = new Intent(getApplicationContext(), MainActivity2.class); startActivity(i); }} |
Kotlin
import android.content.Intentimport android.os.Bundleimport androidx.appcompat.app.AppCompatActivityclass MainActivity : AppCompatActivity() { override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_main) } fun newsScreen() { val i = Intent(applicationContext, MainActivity2::class.java) startActivity(i) }} |
Step 4: Working with the activity_main2.xml File
Now we have to create a second activity as a destination activity. The steps to create the second activity are File > new > Activity > Empty Activity.
Next, go to the activity_main2.xml file, which represents the UI of the project. Below is the code for the activity_main2.xml file. Comments are added inside the code to understand the code in more detail.
XML
<?xml version="1.0" encoding="utf-8"?><androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" tools:context=".MainActivity2"> <TextView android:id="@+id/editText" android:layout_width="match_parent" android:layout_height="wrap_content" android:text="Welcome to GFG News Screen" android:textAlignment="center" android:textSize="28sp" app:layout_constraintBottom_toBottomOf="parent" app:layout_constraintEnd_toEndOf="parent" app:layout_constraintHorizontal_bias="0.0" app:layout_constraintStart_toStartOf="parent" app:layout_constraintTop_toTopOf="parent" /> <Button android:id="@+id/btn2" android:text="Go to Home Screen" android:onClick="homeScreen" android:layout_width="wrap_content" android:layout_height="wrap_content" app:layout_constraintBottom_toBottomOf="parent" app:layout_constraintEnd_toEndOf="parent" app:layout_constraintStart_toStartOf="parent" app:layout_constraintTop_toBottomOf="@+id/editText" /></androidx.constraintlayout.widget.ConstraintLayout> |
Step 5: Working with the MainActivity2 File
Now, we will create the Backend of the App. For this, Open the MainActivity file and instantiate the component (Button, TextView) created in the XML file using the findViewById() method. This method binds the created object to the UI Components with the help of the assigned ID.
Syntax:
ComponentType object = (ComponentType) findViewById(R.id.IdOfTheComponent); Intent i = new Intent(getApplicationContext(), <className>); startActivity(i);
Java
import androidx.appcompat.app.AppCompatActivity;import android.content.Intent;import android.os.Bundle;import android.view.View;public class MainActivity2 extends AppCompatActivity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main2); } public void homeScreen(View view) { Intent i = new Intent(getApplicationContext(), MainActivity.class); startActivity(i); }} |
Kotlin
import android.content.Intentimport android.os.Bundleimport androidx.appcompat.app.AppCompatActivityclass MainActivity2 : AppCompatActivity() { override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_main2) } fun homeScreen() { val i = Intent(applicationContext, MainActivity::class.java) startActivity(i) }} |
