Open one form to another form

activity_main.xml

<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
    android:layout_height="match_parent" android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:paddingBottom="@dimen/activity_vertical_margin"
    tools:context=".MainActivity">


    <LinearLayout
        android:orientation="vertical"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:layout_marginTop="49dp">


        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Main window"
            android:id="@+id/tv" />

        <Button
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Main Button"
            android:id="@+id/btn" />
    </LinearLayout>

</RelativeLayout>

activity_second.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"

    xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"

    android:layout_height="match_parent" android:paddingLeft="@dimen/activity_horizontal_margin"

    android:paddingRight="@dimen/activity_horizontal_margin"

    android:paddingTop="@dimen/activity_vertical_margin"

    android:paddingBottom="@dimen/activity_vertical_margin"

    tools:context="com.example.user.newwindowopen.second">

    <TextView android:text="New window"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content" />

    <Button

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:text="New Button"

        android:id="@+id/btn1"

        android:layout_centerVertical="true"

        android:layout_alignParentLeft="true"

        android:layout_alignParentStart="true" />

</RelativeLayout>

activity_third.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"

    xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"

    android:layout_height="match_parent" android:paddingLeft="@dimen/activity_horizontal_margin"

    android:paddingRight="@dimen/activity_horizontal_margin"

    android:paddingTop="@dimen/activity_vertical_margin"

    android:paddingBottom="@dimen/activity_vertical_margin"

    tools:context="com.example.user.newwindowopen.third">

    <TextView

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:text="Third activity"

        android:id="@+id/tv1"

        android:layout_alignParentTop="true"

        android:layout_alignParentLeft="true"

        android:layout_alignParentStart="true"

        android:layout_marginTop="123dp" />

</RelativeLayout>

MainActivity.java

package com.example.user.newwindowopen;

import android.content.Intent;

import android.support.v7.app.ActionBarActivity;

import android.os.Bundle;

import android.view.Menu;

import android.view.MenuItem;

import android.view.View;

import android.widget.Button;

import android.widget.EditText;

import android.widget.TextView;

import static android.view.View.OnClickListener;

public class MainActivity extends ActionBarActivity implements OnClickListener{

    TextView tv;

    Button btn;

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        init();

    }

    private void init() {

        tv = (TextView) findViewById(R.id.tv);

        btn = (Button) findViewById(R.id.btn);

       btn.setOnClickListener(this);

    }

    @Override

    public void onClick(View v) {

        Intent intent = new Intent(this,second.class);

        this.startActivity(intent);

    }

}

second.java

package com.example.user.newwindowopen;

import android.content.Intent;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

import org.w3c.dom.Text;


public class second extends ActionBarActivity implements View.OnClickListener{

    TextView tv1;
    Button btn1;

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

    private void init() {

        tv1 = (TextView) findViewById(R.id.tv1);
        btn1 = (Button) findViewById(R.id.btn1);
        btn1.setOnClickListener(this);
    }

    public void onClick(View v) {

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

    }
}

third.java

package com.example.user.newwindowopen;

import android.support.v7.app.ActionBarActivity;

import android.os.Bundle;

import android.view.Menu;

import android.view.MenuItem;

public class third extends ActionBarActivity {

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_third);

    }

}