Android使用先前的包/附加功能返回到先前的活动

Question

I have Activity #1: and I move to #Activity 2

Activity1:

Intent PostLogin = new Intent(getApplicationContext(), activity2.class);
        PostLogin.putExtra("email",emailOfUser);
        PostLogin.putExtra("token", authToken);
        PostLogin.putExtra("url", url);
        startActivity(PostLogin);

Activity #2:

ONCREATE ACTIVITY 2:


Intent loginActivity = getIntent();
        token = loginActivity.getStringExtra("token");
        email = loginActivity.getStringExtra("email");
        url = loginActivity.getStringExtra("url");


MOVING TO ACTIVITY 3

 Intent createOrJoin = new Intent(getApplicationContext(), activity3.class);
            createOrJoin.putExtra("token", token);
            createOrJoin.putExtra("url",url );
           // createOrJoin.putExtra("token", );
            startActivity(createOrJoin);

ACTIVITY 3 MOVING BACK TO ACTIVITY 2

Intent backtoPost = new Intent(getApplicationContext(), activity2.class);
                        startActivity(backtoPost);
                        finish();

So I initially have info in Activity 2 I got from Activity 1. Then from Activity 2 I go to Activity 3, where after some stuff I come back to Activity 2.

How can I still have the values of token, email, url ?

Answer 1

There are multiple ways of doing this.

1. One simple way is that you can have them in a variable.

    public class YourActivity extends Activity { String email; public void onCreate(Bundle savedInstanceState) { super.onCreate(); // Set content view etc email = getIntent().getStringExtra("email"); } } 

2. Another better way is to save those variables that you need when onSaveInstancestate is called and then restore them in onCreate or onRestoreInstance . Check following questions for details: onSaveInstanceState () and onRestoreInstanceState () and When are onSaveInstanceState() and onRestoreInstanceState() called, exactly? for how to use them.