Android Intent Tutorial

INTENT :

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.

TYPES OF INTENT :

There are following two types of intents supported by Android

Explicit Intents :

Explicit intent going to be connected internal world of application,suppose if you wants to connect one activity to another activity, we can do this quote by explicit intent, below image is connecting first activity to second activity by clicking button.

These intents designate the target component by its name and they are typically used for application-internal messages - such as an activity starting a subordinate service or launching a sister activity. For example −

// Explicit Intent by specifying its class name
Intent i = new Intent(FirstActivity.this, SecondActivity.class);

// Starts TargetActivity
startActivity(i);

Implicit Intents

These intents do not name a target and the field for the component name is left blank. Implicit intents are often used to activate components in other applications. For example −

Intent read1=new Intent();
read1.setAction(android.content.Intent.ACTION_VIEW);
read1.setData(ContactsContract.Contacts.CONTENT_URI);
startActivity(read1);

INTENT EXAMPLE CODE

ANDROID MANIFEST FILE

AndroidManifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="intent.app.com.intent">
    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <activity android:name=".SecondActivity"></activity>
    </application>
</manifest>

LAYOUT FILES

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    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:orientation="vertical"
    tools:context="intent.app.com.intent.MainActivity">

   <android.support.v7.widget.AppCompatEditText
       android:id="@+id/name"
       android:layout_marginTop="10dp"
       android:imeOptions="actionNext"
       android:layout_width="match_parent"
       android:layout_height="wrap_content"
       android:hint="@string/enter_user_name"
       />

    <android.support.v7.widget.AppCompatEditText
        android:id="@+id/password"
        android:imeOptions="actionGo"
        android:layout_marginTop="10dp"
        android:hint="@string/enter_password"
        android:inputType="textPassword"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />

    <android.support.v7.widget.AppCompatButton
        android:id="@+id/Submit"
        android:text="Submit"
        android:layout_marginTop="10dp"
        android:background="@color/colorAccent"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />

</LinearLayout>

activity_second.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    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:orientation="vertical"
    tools:context="intent.app.com.intent.SecondActivity">

    <android.support.v7.widget.AppCompatTextView
        android:id="@+id/s_name"
        android:layout_marginTop="10dp"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />

    <android.support.v7.widget.AppCompatTextView
        android:id="@+id/s_password"
        android:layout_marginTop="10dp"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />

    <android.support.v7.widget.AppCompatButton
        android:id="@+id/close"
        android:layout_marginTop="10dp"
        android:text="Close"
        android:layout_width="match_parent"
        android:background="@color/colorPrimaryDark"
        android:textColor="#FFFFFF"
        android:layout_height="wrap_content" />

</LinearLayout>

JAVA FILES

MainActivity.java

package intent.app.com.intent;

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;

public class MainActivity extends AppCompatActivity {

    // Initializing variables
    EditText ename, epswd;
    Button submit;
 
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        ename = (EditText)findViewById(R.id.name);
        epswd = (EditText)findViewById(R.id.password);
        submit = (Button)findViewById(R.id.Submit);

        //Listening to button event
        submit.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {

                //Starting a new Intent
                Intent intent= new Intent(MainActivity.this,SecondActivity.class);

                //Sending data to another Activity
                intent.putExtra("Uname",ename.getText().toString());
                intent.putExtra("pswd",epswd.getText().toString());
                startActivity(intent);
            }
        });
    }
}

SecondActivity.java

package intent.app.com.intent;

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

public class SecondActivity extends AppCompatActivity
{

    Button close;
    TextView sname,spswd;

    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_second);

        sname = (TextView)findViewById(R.id.s_name);
        spswd = (TextView)findViewById(R.id.s_password);
        close = (Button)findViewById(R.id.close);

        //For get Intent in Second Screen
        Intent i = getIntent();

        // Receiving the Data
        String Uname = i.getStringExtra("Uname");
        String pswd = i.getStringExtra("pswd");

        // Displaying Received data
        sname.setText(Uname);
        spswd.setText(pswd);

        // Binding Click event to Button
        close.setOnClickListener(new View.OnClickListener()
        {
            @Override
            public void onClick(View view)
            {
                //Closing SecondScreen Activity
                finish();
            }
        });
    }
}