Resume the Top Activity instead of starting the La

问题:

I have two activities in My application, one being launcher and the other is launched as a explicit call from the first.

Here My problem is when i go back to home screen by pressing home key from second activity and launch the application, again the first activity gets initiated even though the second activity is already in the background.

The first Activity is written to download the required assets for the application to work, once the assets are downloaded it triggers the second activity and calls finish for self.

Below is my manifest of the application.

<uses-sdk android:minSdkVersion="7" android:targetSdkVersion="14" />

<application android:icon="@drawable/icon" android:label="@string/app_name" android:theme="@android:style/Theme.NoTitleBar.Fullscreen">

    <! Download the Required Assets if not found on SD Card -->
    <activity android:name=".ContentDownload"
        android:screenOrientation="landscape"
        android:configChanges="keyboard|keyboardHidden|orientation|screenLayout|uiMode|screenSize|smallestScreenSize|locale" 
        android:launchMode="singleTask"
        android:alwaysRetainTaskState="true">

        <intent-filter>
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>

        <intent-filter>
            <action android:name="android.intent.action.SEARCH" />
            <category android:name="android.intent.category.DEFAULT" />
        </intent-filter>

    </activity>

    <activity android:name=".ActualAppActivity" 
        android:screenOrientation="landscape" 
        android:configChanges="keyboard|keyboardHidden|orientation|screenLayout|uiMode|screenSize|smallestScreenSize|locale" 
        android:launchMode="singleTask"
        android:alwaysRetainTaskState="true"
        />

<uses-permission android:name="android.permission.INTERNET"/>
<uses-permission android:name="android.permission.MODIFY_AUDIO_SETTINGS"/>
<uses-permission android:name="android.permission.READ_PHONE_STATE" />
<uses-permission android:name="android.permission.VIBRATE" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/> 
<uses-permission android:name="android.permission.CHANGE_NETWORK_STATE" />
<uses-permission android:name="android.permission.ACCESS_WIFI_STATE"/>  

<supports-screens android:smallScreens="false" android:normalScreens="true" android:largeScreens="true" android:anyDensity="true"/>

Can Somebody please guide me on how to make the second activity gain the control directly instead of going through the first again if launcher is called and it is in the background.

Below is my onResult Call back method.

public void onResult(String assetPath, int result)
{
    if(result == RESULT_OK)
    {
        startActivity(new Intent(this, ActualAppActivity.class));
        activity.destroyDownloadActvity();
        finish();
    }
    else
    {
        finish();
        java.lang.System.exit(0);
    }
    activity.destroyDownloadActvity();
    activity = null;
}

回答1:

Try using the following code in the onCreate method of the activity that is specified as the Launcher Activity in the Manifest, i.e. the ContentDownload activity from the original code posted in the question:

if ((getIntent().getFlags() & Intent.FLAG_ACTIVITY_BROUGHT_TO_FRONT) != 0) {
  finish();
  return;
}

This will finish your Launcher Activity before it is displayed by detecting that there is already a task running, and your app should instead resume to the last visible Activity.

See this page in the Android documentation regarding Android Manifest launchModes: http://developer.android.com/reference/android/R.styleable.html#AndroidManifestActivity_launchMode

回答2:

You've got both your activities defined with launchMode="singleTask". This is the root of your problem. Remove that.

回答3:

I use the following code in the LAUNCHER Activities of my apps to prevent the app from beeing started again when its still alive in the background and the icon is tapped

@Override
protected void onCreate(final Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    if (!isTaskRoot()) {
        finish();
        return;
    }

    // Rest of your onCreate stuff goes here
}

This just finishes the LAUNCHER Activity and resumes the last used one.

回答4:

Do not call finish(). You need to pass to the Intent the flag FLAG_ACTIVITY_CLEAR_TASK and FLAG_ACTIVITY_NEW_TASK.

Intent intent = new Intent(this, ActualAppActivity.class);
intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TASK| Intent.FLAG_ACTIVITY_NEW_TASK);
startActivity(intent);

回答5:

Without seeing your code, I think you want something like this answer:

Android finish Activity and start another one

You need to set intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP); and you'll also need to finish() your launcher activity as well.

回答6:

what you can do is store a string in the persistent storage which determines whether the assets have been loaded before or not.

Then, in the main activity, you may check if the assets have been loaded or not and then start the required activity.

if(assets_already_downloaded)
  second_activity();
else
  download_asset_activity();