java - App stops when switching to another activity in android -

when click button "start party" want android app switch "activity_before_party.xml", when click on button, app stops. have tried many things nothing worked... seems minor problem in opinion. help

this part of "activity_home.xml" (the main page):

<?xml version="1.0" encoding="utf-8"?> <android.support.constraint.constraintlayout xmlns:android="http://schemas.android.com/apk/res/android"     xmlns:app="http://schemas.android.com/apk/res-auto"     xmlns:tools="http://schemas.android.com/tools"     android:layout_width="match_parent"     android:layout_height="match_parent"     android:background="#226b6e"     tools:context="com.example.emili.partymate.home"     tools:layout_editor_absolutey="81dp"     tools:layout_editor_absolutex="0dp">       <button         android:id="@+id/idstartparty"         android:layout_width="260dp"         android:layout_height="61dp"         android:backgroundtint="@color/start_party_color"         android:text="start party!"         android:textcolor="#ffffff"         android:textsize="22sp"         android:onclick="theclick"         app:layout_constraintbottom_totopof="@+id/viewlogs"         app:layout_constrainthorizontal_bias="0.496"         app:layout_constraintleft_toleftof="parent"         app:layout_constraintright_torightof="parent"         app:layout_constrainttop_totopof="parent"         app:layout_constraintvertical_bias="0.285" /> 

this "home.java" :

package com.example.emili.partymate;  import android.support.v7.app.appcompatactivity; import android.os.bundle; import android.view.view; import android.widget.button; import android.content.intent;  public class home extends appcompatactivity {     button startparty;     @override     protected void oncreate(bundle savedinstancestate) {         super.oncreate(savedinstancestate);         setcontentview(r.layout.activity_home);         startparty = (button) findviewbyid(r.id.idstartparty);     }      public void theclick(view v){         intent = new intent(this,beforeparty.class);         startactivity(i);     } } 

this "beforeparty.java"

package com.example.emili.partymate;  import android.support.v7.app.appcompatactivity; import android.os.bundle;  public class beforeparty extends appcompatactivity {     @override     protected void oncreate(bundle savedinstancestate) {         super.oncreate(savedinstancestate);         setcontentview(r.layout.activity_before_party);     } } 

and finally, part of "activity_before_party.xml" (the page want switch to):

<?xml version="1.0" encoding="utf-8"?> <relativelayout xmlns:android="http://schemas.android.com/apk/res/android"     xmlns:tools="http://schemas.android.com/tools"     android:id="@+id/activity_before_party"     android:layout_width="match_parent"     android:layout_height="match_parent"     android:background="#226b6e"     tools:context=".beforeparty"> 

please post error well, otherwise hard find problem. have not register beforeparty activity in androidmanifest.

should that:

<?xml version="1.0" encoding="utf-8"?> <manifest xmlns:android="http://schemas.android.com/apk/res/android"           package="com.your.packename">      <application         android:allowbackup="true"         android:icon="@mipmap/ic_launcher"         android:label="@string/app_name"         android:supportsrtl="true"         android:theme="@style/apptheme">         <activity android:name=".home">             <intent-filter>                 <action android:name="android.intent.action.main"/>                  <category android:name="android.intent.category.launcher"/>             </intent-filter>         </activity>     </application>      <activity android:name=".beforeparty" />  </manifest> 

but again, guess. provide more details , can help.