Android Timer Example

In this example we are going to create a simple Android Timer application.

We are going to use some very basic ideas and tools, like Handler, that you can use in many cases in your Applications. We will use the Handler for the interesting part of this example, which is the timer value update.

For this tutorial, we will use the following tools in a Windows 64-bit platform:

• JDK 1.7
• Eclipse 4.2 Juno
• Android SKD 4.2

1. Create a new Android Project

Open Eclipse IDE and go to File -> New -> Project -> Android -> Android Application Project. You have to specify the Application Name, the Project Name and the Package name in the appropriate text fields and then click Next.

In the next window make sure the “Create activity” option is selected in order to create a new activity for your project, and click Next. This is optional as you can create a new activity after creating the project, but you can do it all in one step.

Select “BlankActivity” and click Next.

You will be asked to specify some information about the new activity.  In the Layout Name text field you have to specify the name of the file that will contain the layout description of your app. In our case the file res/layout/main.xml will be created. Then, click Finish.

2. Adding resources

Use the Package Explorer in Eclipse to navigate to res/values/strings.xml

When you open the strings.xml file, Eclipse will display the graphical Resources View editor :

That’s a nice and easy tool you can use to add several resources to your application like strings, integers, color values etc. But we are going to use the traditional way and that is editing the strings.xml file by hand. In the bottom of the screen, press the string.xml tab and paste the following code :

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

    <string name="app_name">AndroidTimerExample</string>
    <string name="action_settings">Settings</string>
    <string name="hello_world">Hello world!</string>
    <string name="timerVal">00:00:00</string>
    <string name="pauseButtonLabel">Pause</string>
    <string name="startButtonLabel">Start</string>
</resources>

So, we’ve just created some string resources that we can use in many ways and in many places in our app.

3. Create the main layout of the Application

Open res/layout/main.xml file :

And paste the following code :

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:background="#000000"
    android:layout_height="match_parent" >

    <TextView
        android:id="@+id/timerValue"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_above="@+id/pauseButton"
        android:layout_centerHorizontal="true"
        android:layout_marginBottom="37dp"
        android:textSize="40sp"
        android:textColor="#ffffff"
        android:text="@string/timerVal" />

    <Button
        android:id="@+id/startButton"
        android:layout_width="90dp"
        android:layout_height="45dp"
        android:layout_alignParentLeft="true"
        android:layout_centerVertical="true"
        android:layout_marginLeft="38dp"
        android:text="@string/startButtonLabel" />

    <Button
        android:id="@+id/pauseButton"
        android:layout_width="90dp"
        android:layout_height="45dp"
        android:layout_alignBaseline="@+id/startButton"
        android:layout_alignBottom="@+id/startButton"
        android:layout_alignParentRight="true"
        android:layout_marginRight="38dp"
        android:text="@string/pauseButtonLabel" />

</RelativeLayout>

Now you may open the Graphical layout editor to preview the User Interface you created:

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