"The authoritative Guide to Android Programming"-Reading Notes (v)-Challenge practice

"The authoritative Guide to Android Programming"-Reading notes (v)

-Challenge Practice

In order to strengthen learning, in order to build confidence. Start with the following challenges:

Challenge Exercise one: adding listeners to TextView

The book gives hints, Textview,button are all the sub-classes of view, can be set Onclicklistener () directly add the following code:

Mquestiontextview.setonclicklistener (New View.onclicklistener () {

@Override

public void OnClick (View v) {

Mcurrentindex = (mcurrentindex+1)% Mquestionbank.length;

Updatequestion ();

}

});

This modification modifies a file and binds an event to TextView directly at the logical level.

Add the following code:

http://git.oschina.net/canglin/GeoQuiz/commit/6b35ec258c780c9a9d4016c9c3a29e568f21a489

Challenge Exercise II: Add a Back button

• First, we're going to add controls to the Layout/activity_quiz.xml.
• Then we add the text on the button in the Values/strings.xml.
• Defining Variables for Mprevbutton
• Defining events for Prevbutton

When the controls are added, the buttons are arranged in order, and in order for the 2 button to be on one line, I use a linearlayout whose Orientation property is horizontal.

When I define the text of the button, I still use the @string/prev_button, and then I add the text inside the Strings.xml.

When the Prev button arrives at the first of the problem, we stop the fallback. The code is as follows:

Mprevbutton.setonclicklistener (New View.onclicklistener () {

@Override

public void OnClick (View v) {

if (Mcurrentindex >0)

{

mcurrentindex--;

}

Updatequestion ();

}

});

I've modified 3 files for this challenge.

The code is as follows:

http://git.oschina.net/canglin/GeoQuiz/commit/a7868341ae5efff75a024f5e7e6f5197875d0517

Challenge Exercise III: From the button to the icon button

Requirement: Replace the normal button component on the user interface with the ImageButton component.

The ImageButton component inherits the ImageView. The button component inherits TextView. Their inheritance relationship is as follows:

So they can be replaced directly, but ImageButton is not the Text property, so this property must be deleted.

so the code should look like this. Of course , 2 variables Mprevbutton,mnextbutton Remember to change to ImageButton type, there are logic code inside to get object instance also to change to ImageButton.

2 files modified in this modification

The code is as follows:

http://git.oschina.net/canglin/GeoQuiz/commit/3ceadc8f6089801f187a697dfb03185c31c72612

This challenge has been rewarded with the following:

• familiar with adding Onclicklistener () to TextView, Button, ImageButton
• LinearLayout is used for layout.
• The new control ImageButton, and the relationship to the button.

"The authoritative Guide to Android Programming"-Reading Notes (v)-Challenge practice