Hello Button

This example uses more of the Android features: activity stack, menu.
Create a new project named Hello Button.
Change the activity_main.xml to contain this XML code for the app bar and a button.
Add style support for the app bar
- A new file themes.xml in res/values by right clicking on values then "New→Values resource file".
- A new file styles.xml in res/values by right clicking on values then "New→Values resource file".
- New colors.xml
Provide handler for the button click, in MainActivity.java
Add an activity called HelloButtonWorld to this application.
- Use the "File→New→Actvity→Empty Views Actvity" menu to add a new activity
- Name HelloButtonWorld
- Note the new HelloButtonWorld.java and activity_hello_button_world.xml files.
- Notice that the new HelloButtonWorld, as a plain Activity, will not have an action bar.
- Note the activity has been added to the AndroidManifest.xml
Add items for the menu
- Make a new directory in res called menu
- Put this menu XML in res/menu/main_menu.xml
Add code for creating and reacting to the menu in MainActivity.java
- To allow the switch statement to work, add android.nonFinalResIds=false to the end of the gradle.properties
Edit res/values/strings.xml to contain the strings needed
Add permission to use the vibrator to the AndroidManifest.xml
Run the application
- Clicking the button will start the HelloWorld activity, akin to a function call (but not the same).
- The phone's Back button returns from the activity to the previous one.
- Try the menu
An alternative to adding the HelloWorld activity to this application would be to call the HelloWorld activity in the existing Hello World application.
- Change the click handler code to reference it.
- Imagine (or test) what happens then if the Hello World application is not installed on the phone!
Change the icon