Android Beginner: Android activity tutorial

In Android, an activity is represent a single screen. Most applications have multiple activities to represent different screens, for example, one activity to display a list of the application settings, another activity to display the application status.

Note
Refer to this official Android activity article to understand more about Android activity.

In this tutorial, we show you how to interact with activity, when a button is clicked, navigate from current screen (current activity) to another screen (another activity).
P.S This project is developed in Eclipse 3.7, and tested with Android 2.3.3.

1. XML Layouts

Create following two XML layout files in “res/layout/” folder :

1. res/layout/main.xml – Represent screen 1
2. res/layout/main2.xml – Represent screen 2

File : res/layout/main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/linearLayout1"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >
 
    <TextView
        android:id="@+id/textView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="I&apos;m screen 1 (main.xml)"
        android:textAppearance="?android:attr/textAppearanceLarge" />
 
    <Button
        android:id="@+id/button1"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="Click me to another screen" />
 
</LinearLayout>

File : res/layout/main2.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/linearLayout1"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent" >
 
    <TextView
        android:id="@+id/textView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="I&apos;m screen 2 (main2.xml)"
        android:textAppearance="?android:attr/textAppearanceLarge" />
 
</LinearLayout>

2. Activities

Create two activity classes :

1. AppActivity.java –> main.xml
2. App2Activity.java –> main2.xml

To navigate from one screen to another screen, use following code :

    Intent intent = new Intent(context, anotherActivity.class);
    startActivity(intent);

File : AppActivity.java

package com.mkyong.android;
 
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.widget.Button;
import android.view.View;
import android.view.View.OnClickListener;
 
public class AppActivity extends Activity {
 
	Button button;
 
	@Override
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.main);
		addListenerOnButton();
	}
 
	public void addListenerOnButton() {
 
		final Context context = this;
 
		button = (Button) findViewById(R.id.button1);
 
		button.setOnClickListener(new OnClickListener() {
 
			@Override
			public void onClick(View arg0) {
 
			    Intent intent = new Intent(context, App2Activity.class);
                            startActivity(intent);   
 
			}
 
		});
 
	}
 
}

File : App2Activity.java

package com.mkyong.android;
 
import android.app.Activity;
import android.os.Bundle;
import android.widget.Button;
 
public class App2Activity extends Activity {
 
	Button button;
 
	@Override
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.main2);
	}
 
}

3. AndroidManifest.xml

Declares above two activity classes in AndroidManifest.xml.
File : AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.mkyong.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:label="@string/app_name"
            android:name=".AppActivity" >
            <intent-filter >
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <activity
            android:label="@string/app_name"
            android:name=".App2Activity" >
        </activity>
    </application>
 
</manifest>

4. Demo

Run application.
AppActivity.java (main.xml) screen is display.

                                      

When above button is clicked, it will navigate to another screen App2Activity.java (main2.xml).

Add caption

                                  

Download Source Code

Download it – Android-From-Screen-To-Screen-Acticity-Example.zip (16 KB)