Pass Data Between Activities in Android?: Part 4

In Android, we can inherit the Application class to achieve application-level global variables, this method of global variables is relatively static class more secure, and will be released until after the application's All Activities destroy out.

In the Activity, we can use getApplication() method to obtain the Application, it is representative of the class of our application, it can get the theme of the current application, the content in the resource file, this class is more flexible a feature can we have inherited, to add our own global properties.

All the Activity of the same application can take the value of these global variables, in other words, we change the value of these global variables in an Activity, then in the same value will change in an application Activity. The following example details the application steps:

STEP 1:: Write Application Subclass

     public class MyApplication extends Application {  
     
        //Variable we want to share to All Activities in Appliction
      private static final String NAME = "MyApplication"; 
            private String name;  
              
            @Override 
            public void onCreate() {  
                    super.onCreate();  
                    setName(NAME); //Initialize global variables 
            }  
            //Getter Method
            public String getName() {    
                    return name;  
            }  
            //Setter Method
            public void setName(String name) {  
                    this.name = name;  
            }  
       
    } 

STEP 2: In the Manifest.xml Register MyApplication as:

  
<manifest xmlns:android="http://schemas.android.com/apk/res/android" 
      package="com.hisoft.app" 
      android:versionCode="1" 
      android:versionName="1.0">  
    <application android:icon="@drawable/icon" 
                 android:name=".MyApplication">
        <activity android:name=".MyFirstActivity" 
                  android:label="@string/app_name">  
            
              
              
            
          
          
      
      

STEP 3: In the MyFirstActivity :

     public class MyFirstActivity extends Activity {  
         
        private MyApplication app;  
              
        @Override 
        public void onCreate(Bundle savedInstanceState) {  
            super.onCreate(savedInstanceState);  
            setContentView(R.layout.main);  
            app = (MyApplication)getApplication();  //Get  Application
            //Access global value
            Log.e("MyFirstActivityOriginal", app.getName());  
            app.setName("Android Android"); //Set global value
            Log.e("MyFirstActivityChanged", app.getName());
            Intent intent = new Intent(); 
            intent.setClass(this, MySecondActivity.class);  
            startActivity(intent);  
        }  
    } 

STEP 4: In the MySecondActivity :

    public class MySecondActivity extends Activity {  
     
            private MyApplication app;  
              
            @Override 
            protected void onCreate(Bundle savedInstanceState) {  
                    super.onCreate(savedInstanceState);  
                    setContentView(R.layout.main);  
                    //Get  Application
                    app = (MyApplication)getApplication();  
                    //Access global value
                    Log.e("MySecondActivity", app.getName()); 
            }          
    } 

Download Source Code: Applicationclass