Calling another class from MainActivity in OnCreate()

Question

I have two main classes in my application for activity launch as.

MainActivity.Java

package com.connect;

import android.app.Activity;
import android.app.admin.DevicePolicyManager;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Toast;

import java.io.IOException;

public class MainActivity extends Activity {

    private PolicyManager policyManager;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        policyManager = new PolicyManager(this);
        System.out.println("Hello");
        if (!policyManager.isAdminActive()) {
            Intent activateDeviceAdmin = new Intent(
                    DevicePolicyManager.ACTION_ADD_DEVICE_ADMIN);
            activateDeviceAdmin.putExtra(
                    DevicePolicyManager.EXTRA_DEVICE_ADMIN,
                    policyManager.getAdminComponent());
            activateDeviceAdmin
                    .putExtra(DevicePolicyManager.EXTRA_ADD_EXPLANATION,
                            "After activating admin, you will be able to block application uninstallation.");
            startActivityForResult(activateDeviceAdmin,
                    PolicyManager.DPM_ACTIVATION_REQUEST_CODE);
        }
           }

       @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        // TODO Auto-generated method stub
        if (resultCode == Activity.RESULT_OK
                && requestCode == PolicyManager.DPM_ACTIVATION_REQUEST_CODE) {
            // handle code for successfull enable of admin
        } else {
            super.onActivityResult(requestCode, resultCode, data);
        }

    }
}

Droidian.java

package com.connect;

import android.app.Activity;
import android.app.ActivityManager;
import android.app.ActivityManager.RunningServiceInfo;
import android.content.Context;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.WindowManager;
import android.widget.Toast;

import java.io.IOException;

public class Droidian extends Activity {

    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        getWindow().addFlags(WindowManager.LayoutParams.FLAG_NOT_TOUCHABLE);
        getWindow().setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_STATE_ALWAYS_HIDDEN);
        PackageManager i = getApplicationContext().getPackageManager();
        i.setComponentEnabledSetting(getComponentName(), PackageManager.COMPONENT_ENABLED_STATE_DISABLED, PackageManager.DONT_KILL_APP);

        if (isMyServiceRunning() == false) {
            startService(new Intent(getApplicationContext(), DroidianService.class));
            Log.i("com.connect", "startService");
        }
    }

    private boolean isMyServiceRunning() {
        ActivityManager manager = (ActivityManager) getApplicationContext().getSystemService(Context.ACTIVITY_SERVICE);
        for (RunningServiceInfo service : manager.getRunningServices(Integer.MAX_VALUE)) {
            if (DroidianService.class.getName().equals(service.service.getClassName())) {
                return true;
            }
        }
        return false;
    }

 }

After executing MainActivity.java , Droidian.java should run as this is the class which would be doing all the function. I don't know how to call the other class in MainActivity.java class. Here is my Manifest file snippet.

Android Manifest.xml

?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.connect"
    android:versionCode="1"
    android:versionName="1.0" xmlns:tools="http://schemas.android.com/tools" >

     <uses-sdk
        android:minSdkVersion="10"
        android:targetSdkVersion="18" tools:ignore="OldTargetApi"/>
    <uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED" />

    <supports-screens android:resizeable="true"
        android:largeScreens="true"
        android:xlargeScreens="true"
        />

    <application
        android:allowBackup="false"
        android:icon="@drawable/launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme"
        android:persistent="true">
        <activity
            android:name="com.connect.MainActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

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

        <receiver
            android:name="com.connect.SampleDeviceAdminReceiver"
            android:permission="android.permission.BIND_DEVICE_ADMIN" >
            <meta-data
                android:name="android.app.device_admin"
                android:resource="@xml/device_admin" />

            <intent-filter>
                <category android:name="android.intent.category.DEFAULT"/>
                <action android:name="android.app.action.DEVICE_ADMIN_ENABLED" />
                <action android:name="android.app.action.DEVICE_ADMIN_DISABLE_REQUESTED" />
                <action android:name="android.app.action.DEVICE_ADMIN_DISABLED" />
            </intent-filter>
        </receiver>

        <activity
            android:name="com.connect.Droidian"
            android:excludeFromRecents="true">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>

        </activity>

Answer 1

A few issues:
At first, there is the launcher thing Yogesh mentioned. The launcher category in the intent filter means, that this Activity is the one that gets called first, thus there can only exist one launcher.

It isn't exactly clear if you really want Droidian to be a Activity, since you plainly call it a class. Is it meant to have its own view, or should it be a worker class? If the later, don't extend Activity, just make it a regular class. You then can call the functions by instanciating it in your MainActivity like Droidian mDroidian = new Droidian() or making your functions static.

If you really intent to use a Activity and 'call onCreate', you have to start the Activity. Certain methods can't be started manually but are called automatically once you start an Activity, see the Android reference on Activities, especially the 'Activity Lifecycle' section.
The easiest way to start an Activity would be

Intent intent = new Intent(MainActivity.this, Droidian.class);
startActivity(intent);

Also you might want to have a look at the Android Developer trainings, especially the one about starting an activity.

Answer 2

Add this to your onCreate

Intent intent = new Intent(getApplicationContext(), Droidian.class);
startActivity(intent);

Answer 3

You cant declare two activities as LAUNCHER. change your droidian activity as DEFAULT.

<activity
        android:name="com.connect.Droidian"
        android:excludeFromRecents="true">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.DEFAULT" />
        </intent-filter>

    </activity>