从库开始结果的活动

Question

I want to call an activity for result from an class that is refrenced from library . I have main project say p1 and another project say p2 which is added as library to p1, and inside p2 I have class : MiddleWareStart and from it I want to call an activity that belongs to p2 : DeviceListActivity I have tried to use startActivityForResult from MiddleWareStart but it dosn't work and cause runtime error ,and so I tried to put the main activity from p1 when refrencing MiddleWareStart as:

MiddleWareStart x=new MiddleWareStart(mainActivity.this);

and inside MiddleWareStart I put Activity a, and in the constructor:

public MiddleWareStart(Activity activity)
{
this.a=activity;
Intent intent=new Intent(a,DeviceListActivity.class);   
a.startActivityForResult(intent,1);

}

Now it works and the activity DeviceListActivity.java is started , but the problem that on Activity Result that is implemented inside the MiddleWareStart is never called. and i have declared the set Resullt inside the called activity (DeviceListActivity) . And when I try to launch p2 itself (not p1) every think work correctly as expected and on Activity Result is called here the needed code:

Inside mainActivity (GameActivity) inside p1

MiddleWareStart x=new (GameActivity.this);

Inside MiddleWareStart (inside p2)

public class MiddleWareStart extends Activity
{

Activity a;
public MiddleWareStart(Activity activity)
{  

 this.a=activity;
 Intent intent=new Intent(a,DeviceListActivity.class);
 a.startActivityForResult(intent,1);
 Toast.makeText(this,"Check toast",5).show();  
}


public void onActivityResult(int requestCode, int resultCode, Intent data) {    

    super.onActivityResult(requestCode, resultCode, data);
    switch (requestCode) {
    case 1:
             Toast.makeText(this,"inside on activity result",5).show();         
        if (resultCode == Activity.RESULT_OK) {
            Toast.makeText(this,"ok",5).show(); 
             }
    break;
    case2:----
    }
  }
}

The output only show Check toast

Also I tried to put onActivityResult inside main.java but also it hasn't been called

Inside DeviceListActivity:

Intent intent = new Intent();
        intent.putExtra(EXTRA_DEVICE_ADDRESS, address);

        // Set result and finish this Activity
        setResult(Activity.RESULT_OK, intent);

And here my manifest file for the main project:

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
  package="com.example.android.tictactoe.library"
  android:versionCode="1"
  android:versionName="1.0"
   android:name="com.example.GlobalState">
<uses-sdk android:minSdkVersion="8" />   
<uses-permission android:name="android.permission.BLUETOOTH_ADMIN" />
<uses-permission android:name="android.permission.BLUETOOTH" />
<uses-permission android:name="android.permission.WRITE_SYNC_SETTINGS"></uses-permission>
<application android:icon="@drawable/icon" android:label="@string/tie" 
     android:name="com.example.GlobalState">
    <activity android:name=".GameActivity"
              android:label="@string/tie">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
    <activity android:name="com.example.DeviceListActivity"
              android:label="@string/select_device"

              android:configChanges="orientation|keyboardHidden" >

    </activity>
    <activity android:name="com.example.MiddleWareStart"
              android:label="@string/select_device"                  
              android:configChanges="orientation|keyboardHidden" >

    </activity>
</application>

And here the manifest for the library project:

  android:versionCode="1"
  android:versionName="1.0">
<uses-sdk minSdkVersion="6" />
<uses-permission android:name="android.permission.BLUETOOTH_ADMIN" />
<uses-permission android:name="android.permission.BLUETOOTH" />
<uses-permission android:name="android.permission.WRITE_GSERVICES"></uses-permission>
<uses-permission android:name="android.permission.CALL_PHONE"></uses-permission>
<uses-permission android:name="android.permission.WRITE_SYNC_SETTINGS"></uses-permission>


<application android:label="@string/app_name"

              >
    <activity android:name=".MiddleWareStart"
              android:label="@string/app_name"
              android:configChanges="orientation|keyboardHidden">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
    <activity android:name=".com.example.DeviceListActivity"
              android:label="@string/select_device"

              android:configChanges="orientation|keyboardHidden" />
</application>

Thank you for reading any suggestion will be usefull

Answer 1

Be careful, storing a reference to an Activity in a variable can lead to unexpected problems, because Android can destroy the activity whenever it wants (to free memory).

Instead, you can call startActivityForResult() directly from your second activity, get the result, then use broadcast receivers to notify your first activity.

Answer 2

MiddleWareStart extends Activity but you don't start it as an activity so it's not in the "activity stack" and cannot act as the calling activity. Hence the exception. If you call a.StartActivityForResult - a is the calling activity and therefore a's onActivityResult will be invoked. Hope that helps.