Android Learning _7 / 22

A, Android project directory structure

1. AndroidManifest.xml : the entire Android configuration items, registration of the components

<activity android:name=".MainActivity" >
    <intent-filter>
        <action android:name="android.intent.action.MAIN" />         //主活动

        <category android:name="android.intent.category.LAUNCHER" />     //首先启动的活动
    </intent-filter>
</activity>

2. Activity

Separating the view logic

. 1) AppCompatActivity : backward compatible with the Activity , the Activity subclass.

2) oneCreate () method: create an event will execute.

3. build.gradle file

1) Gradle is a project build tools

2) a project has two build.gradle

a) under the outermost catalog: Global project build configuration, generally without modification

b) App directory

defaultConfig闭包：

applicationId : In this modification package name

dependencies闭包：

Dependencies project: local, library, remote

Second, resources

Reference resources :

Code by R.string.app_name

XML via @ string / app_name

Third, use the logging facility

1. log.v () log.d() log.i() log.w() log.e()

Level: Low → High

2. Log.d("MainActivity","oneCreate execute");

Tag : Filter print information ( usually the name of the current class, logt can be generated automatically TAG constant )

msg : the specific content of print

3. logcat : filter, log level control, keyword filtering

Fourth, the basic usage activity

1. Create Event

2. Create and load distribution

A) XML Definition Id : Atto Tasu Id / Button_1

b) loading layout: the setContentView (R.layout.first_layout);

3. In AndroidManifest registration

By <Activity> , in <application> lower ( automatic registration )

a) a statement of the main activities:

b) plus the title bar

4. activity using Toast

// findViewById () Gets the layout elements defined, then View down converted to the Button
        the Button Button1 = (the Button) the findViewById (R.id. Button_1 ) ;
        / *
        * the Button is setOnClickListener () Method : register a listener
        * Toast .makeText () method : create Toast Object
        * there seems to use anonymous inner classes? Java foundation not quite sure. . .
       * * /
// button1.setOnClickListener (new new View.OnClickListener () {
            @Override
            public void the onClick (View V) {
                Toast. MakeText (FirstActivity. The this,"You click Button 1",
                        Toast.LENGTH_SHORT).show();
            }
        });

step1 : the definition of trigger points - Button ( use findViewById () Gets )

stpe2 : listener registered for the button, the listener has OnClick () method, click the button on the implementation OnClick ()

stpe3 : the OnClick () call Toast.makeText () to create Toast objects, this method has three parameters: Context , text display, the display duration

Android Learning _7 / 22

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