This is a series of post as I will hopefully build a simple wallpaper app.
In this app, we will build a simple counter which counts the number of times a button in the app was pressed.
Firstly we should design layout of the app. It should have text which is the counter and a button. Be give the button and the counter id’s so that it can be referenced in our code.
Here is my .xml, it is okay if your one is different!
<TextView
android:text="@string/hello_world"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_above="@+id/button_counter"
android:layout_alignParentTop="true"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true" />
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="The Button"
android:id="@+id/button"
android:layout_alignParentBottom="true"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:layout_alignParentRight="true"
android:layout_alignParentEnd="true" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/button_counter"
android:id="@+id/button_counter"
android:layout_above="@+id/button"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:layout_alignParentRight="true"
android:layout_alignParentEnd="true" />
Now that the layout is complete, we may want to add or alter the values in string.xml. Here is what my one looks like.
<string name="app_name">SimpleButton</string>
<string name="hello_world">Hello world! This keeps track of the number of times you pressed the button</string>
<string name="action_settings">Settings</string>
<string name="button_counter">0</string>
Since all of this should be simple and revision, lets consider the .java code. Similar to my previous post, in order to add the activity, we will have define the activity after onCreate function.
The auto-complete function in Android studio will give you the boiler plate if you choose to use it. It will look something like this:
Button button = (Button) findViewById(R.id.button);
button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
}
});
Now we simply have to define the activity within onClick to incrememt the text in our layout. One way would be to create a counter within the class and increment it globally, assigning it via setText().
This would look something like this:
public void incrementCount() {
// increments the counter counting the number of times the button was pressed.
TextView incrementCounter = (TextView) findViewById(R.id.button_counter);
counter++;
incrementCounter.setText(""+counter);
}
Placing this function within onClick should provide the solution.