Understanding and use of context in Android (ii) use of--application

To achieve data sharing capabilities:In multiple activity, you can use application to share data, because application is unique to the same application.

1, the realization of the global sharing of data App.java inherit from application:

Public class APP extends Application {

Private String TextData = "Default";

Public void Settextdata (String textData) {
This . textData = textData; 　　　　　　　　
}
Public String Gettextdata () {
return textData; 　　　　　　　　
}
}

and configure Androidmanifest.xml: android:name= ". App "

2, create the class Main2 inherit from activity (will render two icons on the start page, these two activity is the application's entrance),

and configure Androidmanifest.xml:

< activity Android:name= ". Mainactivity "android:label=" Main1 ",
<intent-filter>
<action android:name=" Android.intent.ac tion. MAIN "/>
<category android:name=" Android.intent.category.LAUNCHER "/> <!--start-->
</int Ent-filter>
</activity>
<activity android:name=. Main2 "android:label=" Main2 ",
<intent-filter>
<action android:name=" Android.intent.action.MA　　In "/>
<category android:name=" Android.intent.category.LAUNCHER "/>
</intent-filter>
</activity>

3, create Main1.xml and Main2.xml, are the same layout:

<textview
android:text= "Show saved Content"
android:layout_width= "Match_parent"
android:layout_height= "Wrap_content"
android:id= "@+id/textview"/>

<edittext
android:layout_width= "Match_parent"
android:layout_height= "Wrap_content"
android:id= "@+id/edittext"/>

<button
android:text= "Save"
android:layout_width= "Match_parent"
android:layout_height= "Wrap_content"
android:id= "@+id/btnsavedata"/>

4, Mainactivity.java and Main2.java function realization:

Public class Mainactivity extends Appcompatactivity {

private TextView TextView;
private EditText EditText;

@Override
protected void OnCreate (Bundle savedinstancestate) {
super.oncreate (savedinstancestate);
Setcontentview (r.layout.main1); //Setcontentview (r.layout.main2);

TextView = (TextView) Findviewbyid (R.id.textview);
EditText = (editText) Findviewbyid (R.id.edittext);
Textview.settext ("Shared data is:" +getapp (). Gettextdata ());

Findviewbyid (R.id.btnsavedata). Setonclicklistener (New View.onclicklistener () {
@Override
public void OnClick (View v) {
Getapp (). Settextdata (Edittext.gettext (). toString ());
Textview.settext ("Shared data is:" +edittext.gettext (). toString ());
}
});
}
　　　　Public App Getapp () {
Return (APP) Getapplicationcontext ();
}
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Understanding and use of context in Android (ii) use of--application