Android - Intent: llamar a otro activity desde MainActivity.java

package ar.com.utn.penny.converter;

import android.content.Intent;

import android.provider.MediaStore;

import android.support.v7.app.AppCompatActivity;

import android.os.Bundle;

public class MainActivity extends AppCompatActivity {

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

    }

    public void botonHolaMundo(View v){

        Intent i= new Intent(this, Activity2.class);

        stactivity(i);

    }

}

public class Activity2 extends AppCompatActivity {

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

    }

}

public void botonHolaMundo(View v){

    Intent i= new Intent(this, Activity2.class);

    startActivity(i);

}

public void botonHolaMundo(View v){

    Intent i= new Intent(getApplicationContext(), Activity2.class);

    startActivity(i);

}

public void botonHolaMundo(View v){

    Intent i= new Intent(getApplicationContext(), Activity2.class);

    startActivity(i);

}

<activity android:name=".Activity2">

    <intent-filter>

        <action android:name="android.intent.action.VIEW"/>

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

    </intent-filter>

</activity>

<activity

    android:name=".Activity1"

    android:label="@string/app_name"

    android:theme="@style/AppTheme.NoActionBar">

    <intent-filter>

        <action android:name="android.intent.action.MAIN" />

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

    </intent-filter>

</activity>

//Aqui declaras la segunda activity

// Como ves todo va dentro de activity

//Ahora despues de esta activity declaras la segunda activity

<activity android:name=".Activity2"></activity>