千万不要把数据存储在Application对象中

The Application object:

// access modifiers omitted for brevity
classMyApplication extends Application {
 
    String name;
 
    String getName() {
        returnname;
    }
 
    voidsetName(String name) {
        this.name = name;
    }
}

The first activity, where we store the name of the user in the application object:

// access modifiers omitted for brevity
classWhatIsYourNameActivity extends Activity {
 
    voidonCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.writing);
 
        // Just assume that in the real app we would really ask it!
        MyApplication app = (MyApplication) getApplication();
        app.setName("Developer Phil");
        startActivity(newIntent(this, GreetLoudlyActivity.class));
 
    }
 
}

The second activity, where we shout the name of the user:

// access modifiers omitted for brevity
classGreetLoudlyActivity extends Activity {
 
    TextView textview;
 
    voidonCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
 
        setContentView(R.layout.reading);
        textview = (TextView) findViewById(R.id.message);
    }
 
    voidonResume() {
        super.onResume();
 
        MyApplication app = (MyApplication) getApplication();
        textview.setText("HELLO " + app.getName().toUpperCase());
    }
}