Previously , we learn how to implement contextual menus on Long press in android : Contextual Menu Implementation in Android. Now, here we unfold some intent concepts!!

You can start another activity within the same application by calling startActivity(), passing it an Intent that describes the activity “class name” you want to start. Alternatively, if the activity to be started has an action name defined within <intent-filter> in the AndroidManifest.xml we can use to call the activity too. 

There are two ways to open a new activity.

·         Using the "startactivity(Intent intent)" method

·         Using "startActivityforResult(Intent intent, requestCode requestCode)" method. 

When we open a folder or file using another for importing or save some data then we use startActivityforResult(),Because by calling this second Activity the open is only for some time and provides some output. Whereas startActivity() opens a separate new activity. 

Pre-Requisites: 

1.       Ellipse SDK

2.       Android SDK

3.       ADT plugin

Or Android Studio and a compatible version of JAVA SDK

Install and configure the above utilities.

Now create a new Android project namely “MindStickActivity”. 

Implementation objective: 

·        How to call “start” another activity within the same application?

·         How to prepare the Intent object using class name or action name?

·         How to send data from one activity to another activity using putExtra() method

·         How to receive data from sending activity and use it. 

Creating GUI’s for the Activities: 

Define the layout for the first “main” activity and the second “new” activity to be started.

We need

1.      For Main activity :A Linear Layout consist of a Text View(Indicating about current Activity) and a button  which will help us trigger the new activity

2.      For New activity :A Linear Layout consist of a Text View(Indicating about current Activity) and another  Text View  which will show the data send by the main Activity

Open "MindStickActivity/res/layout/activity_main.xml" from package explorer and update it as in the following code:

<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:paddingLeft="@dimen/activity_horizontal_margin"

    android:paddingRight="@dimen/activity_horizontal_margin"

    android:paddingTop="@dimen/activity_vertical_margin"

    android:paddingBottom="@dimen/activity_vertical_margin"

    android:orientation="vertical"

    tools:context=".MainActivity">

    <TextView

        android:text="Main Activity"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content" />

    <Button

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:id="@+id/button_start"

        android:text="Start New Activity"/>

</LinearLayout>

 Now navigate to "MindStickActivity/res/layout/activity_new.xml" from package explorer. Open activity_new.xml

<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="com.example.msclient010.mindstickactivity.NewActivity">
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/newText"
        android:text="We are in new Activity"/>
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/data_text"
        />

</LinearLayout>

  Creating new Activity: 

Create a new Activity Java file named "NewActivity.java” and the following code will be generated in it:

package com.example.msclient010.mindstickactivity;
import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.TextView;


public class NewActivity extends ActionBarActivity {

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

    }
    @Override
    public boolean onCreateOptionsMenu(Menu menu) {

        // Inflate the menu; this adds items to the action bar if it is present.

        getMenuInflater().inflate(R.menu.menu_new, menu);

        return true;
    }
    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }
}

Updating Android Manifest file: 

Now open AndriodManifest.xml and update following code in it:

<?xml version="1.0" encoding="utf-8"?>

<manifest xmlns:android="http://schemas.android.com/apk/res/android"

    package="com.example.msclient010.mindstickactivity" >

    <application

        android:allowBackup="true"

        android:icon="@drawable/ic_launcher" 
        android:label="@string/app_name" 
        android:theme="@style/AppTheme" > 
        <activity 
            android:name=".MainActivity" 
            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=".NewActivity" 
            android:label="@string/title_activity_new" > 
        </activity> 
    </application> 
</manifest>

package com.example.msclient010.mindstickactivity; 
import android.content.Intent; 
import android.os.Bundle; 
import android.support.v7.app.ActionBarActivity; 
import android.view.Menu; 
import android.view.MenuItem; 
import android.view.View; 
import android.widget.Button;

public class MainActivity extends ActionBarActivity {

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
        super.onCreate(savedInstanceState); 
        setContentView(R.layout.activity_main); 
        //getting a reference to the Start New Activity button 
        Button btn = (Button)findViewById(R.id.button_start); 
        //making the button clickable 
        btn.setOnClickListener( new View.OnClickListener() { 
            @Override 
            public void onClick(View v) { 
                //creating an intent instance to start a new activity 
                Intent i= new Intent(MainActivity.this,NewActivity.class); 
                //passing data from main activity to new activity 
                i.putExtra("Text","Data from Main activity to New Activity"); 
                //Starting New activity 
                startActivity(i); 
            } 
        }); 
    } 
    @Override 
    public boolean onCreateOptionsMenu(Menu menu) { 
        // Inflate the menu; this adds items to the action bar if it is present. 
        getMenuInflater().inflate(R.menu.menu_main, menu); 
        return true; 
    } 
    @Override 
    public boolean onOptionsItemSelected(MenuItem item) { 
        // Handle action bar item clicks here. The action bar will 
        // automatically handle clicks on the Home/Up button, so long 
        // as you specify a parent activity in AndroidManifest.xml. 
        int id = item.getItemId(); 
        //noinspection SimplifiableIfStatement 
        if (id == R.id.action_settings) { 
            return true; 
        } 
        return super.onOptionsItemSelected(item); 
    } 
}

package com.example.msclient010.mindstickactivity;
import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.TextView;

public class NewActivity extends ActionBarActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_new);
        //getting reference of data_text Text view
        TextView dataTxt = (TextView)findViewById(R.id.data_text);
       // Getting String data from the main activity
        String data = getIntent().getStringExtra("Text");
        //setting the string data from main activity to the textView
        dataTxt.setText(data);
    }
    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_new, menu);
        return true;
    }
    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();
        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }
}