How to start an Android activity from a Unity Application?

Question

I know this seems to be a trivial question but I could not find any concrete answer anywhere on the internet. I saw this very similar question on stackoverflow: How to start Unity application from android activity? but it is exactly opposite from my question. Additionally the android activity must be able to receive some input strings from the Unity application much like how one use system() calls with line arguments to start another program on a PC.

The following is the code I have for a test button event handler for my test Unity app on Android:

private void ExternalAppCallHandler()
{
    if(Application.platform == RuntimePlatform.WindowsEditor)
    {
        Process.Start(@"C:\Program Files (x86)\Notepad++\notepad++.exe");
    }
    else if(Application.platform == RuntimePlatform.Android)
    {
        Process.Start("Internet");
    }
}

When I use Unity Editor to test, the application successfully opens Notepad++.exe when I click on the test button. However, when I tried to open the "Internet" app on my Samsung Galaxy S2 device it failed. Does anyone knows why this is the case? What should be the correct string for opening another Android application using Process.Start?

Answer 1

I am not very familiar with Unity, but have a fair amount of Android experience. So take my answer as a suggestion rather than an authoritative answer.

Looking at the Launching an Android application from within Unity, you could try the following:

Follow the Guide on Integrating Unity with Eclipse.

Modify the Java file created in Step 1 as below:

package com.Unity3D.EclipseIntegration;

import android.os.Bundle;

import com.unity3d.player.UnityPlayerActivity;

public class EclipseIntegration extends UnityPlayerActivity {

    private Intent myIntent;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        //Assuming that we want to launch the browser to browse a website
        Uri uri = Uri.parse("http://www.google.com");
        myIntent= new Intent(Intent.ACTION_VIEW, uri);
    }

    public void Launch()
    {       
        startActivity(myIntent);
    }
}

and modify your Unity code:

private void ExternalAppCallHandler()
{
    if(Application.platform == RuntimePlatform.WindowsEditor)
    {
        Process.Start(@"C:\Program Files (x86)\Notepad++\notepad++.exe");
    }
    else if(Application.platform == RuntimePlatform.Android)
    {
        AndroidJavaClass jc = new AndroidJavaClass("com.unity3d.player.UnityPlayer");
        AndroidJavaObject jo = jc.GetStatic<AndroidJavaObject>("currentActivity");
        jo.Call("Launch");
    }
}

In case you are facing any problems, please post the LogCat messages.