diff --git a/app/src/main/java/com/example/drp25/Database.kt b/app/src/main/java/com/example/drp25/Database.kt
index 52dc9c2..6df0275 100644
--- a/app/src/main/java/com/example/drp25/Database.kt
+++ b/app/src/main/java/com/example/drp25/Database.kt
@@ -31,8 +31,35 @@ fun addMatchObserver(observer: Observer) {
 
 fun addMatched(uniId: String, user1Id: String, user2Id: String) {
     val usersRef = unisRef.child(uniId).child("users")
-    usersRef.child(user1Id).child("matched").push().setValue(user2Id)
-    usersRef.child(user2Id).child("matched").push().setValue(user1Id)
+    val key1 = usersRef.child(user1Id).child("matched").push()
+    val key2 = usersRef.child(user2Id).child("matched").push()
+    key1.child("matchId").setValue(user2Id)
+    key2.child("matchId").setValue(user1Id)
+
+    usersRef.child(user1Id).child("interests").addListenerForSingleValueEvent(object: ValueEventListener {
+        override fun onDataChange(snapshot1: DataSnapshot) {
+            usersRef.child(user2Id).child("interests").addListenerForSingleValueEvent(object: ValueEventListener {
+                override fun onDataChange(snapshot2: DataSnapshot) {
+                    for (child in snapshot1.children) {
+                        if (child.key?.let { snapshot2.hasChild(it) } == true) {
+                            key1.child("sharedInterests").push().setValue(child.key)
+                            key2.child("sharedInterests").push().setValue(child.key)
+                        }
+                    }
+                }
+
+                override fun onCancelled(error: DatabaseError) {
+                    TODO("Not yet implemented")
+                }
+
+            })
+        }
+
+        override fun onCancelled(error: DatabaseError) {
+            TODO("Not yet implemented")
+        }
+
+    })
 }
 
 fun listenToUser(uniId: String, userId: String) {
diff --git a/app/src/main/java/com/example/drp25/InterestActivity.kt b/app/src/main/java/com/example/drp25/InterestActivity.kt
index d7a707a..ffa2254 100644
--- a/app/src/main/java/com/example/drp25/InterestActivity.kt
+++ b/app/src/main/java/com/example/drp25/InterestActivity.kt
@@ -1,5 +1,6 @@
 package com.example.drp25
 
+import android.annotation.SuppressLint
 import android.content.Intent
 import androidx.appcompat.app.AppCompatActivity
 import android.os.Bundle
@@ -13,14 +14,79 @@ import com.google.firebase.database.DataSnapshot
 import com.google.firebase.database.DatabaseError
 import com.google.firebase.database.FirebaseDatabase
 import com.google.firebase.database.ValueEventListener
+import okhttp3.internal.notify
 
 class InterestActivity : AppCompatActivity() {
 
+    enum class HobbyCategory {
+        ACADEMIC_RELATED,
+        ARTS_ENTERTAINMENT,
+        CHARITABLE,
+        INDOOR,
+        OUTDOOR,
+        SOCIAL,
+        SPORTS
+    }
+
+    val hobbiesCategoriesMap = mapOf(
+        "Anime" to listOf(HobbyCategory.ARTS_ENTERTAINMENT),
+        "Archery" to listOf(HobbyCategory.SPORTS, HobbyCategory.OUTDOOR),
+        "Art" to listOf(HobbyCategory.ARTS_ENTERTAINMENT),
+        "Astronomy" to listOf(HobbyCategory.ACADEMIC_RELATED),
+        "Badminton" to listOf(HobbyCategory.SPORTS, HobbyCategory.INDOOR),
+        "Baking" to listOf(HobbyCategory.ARTS_ENTERTAINMENT),
+        "Baseball and Softball" to listOf(HobbyCategory.SPORTS, HobbyCategory.OUTDOOR),
+        "Basketball" to listOf(HobbyCategory.SPORTS, HobbyCategory.OUTDOOR),
+        "Bridge" to listOf(HobbyCategory.SOCIAL),
+        "Caving" to listOf(HobbyCategory.OUTDOOR),
+        "Charity and Volunteering" to listOf(HobbyCategory.CHARITABLE, HobbyCategory.SOCIAL),
+        "Choir and Chamber Music" to listOf(HobbyCategory.ARTS_ENTERTAINMENT),
+        "Chess" to listOf(HobbyCategory.SOCIAL),
+        "Cycling" to listOf(HobbyCategory.SPORTS, HobbyCategory.OUTDOOR),
+        "Dance" to listOf(HobbyCategory.ARTS_ENTERTAINMENT),
+        "Dogs" to listOf(HobbyCategory.SOCIAL),
+        "Drama" to listOf(HobbyCategory.ARTS_ENTERTAINMENT),
+        "Environmental" to listOf(HobbyCategory.CHARITABLE),
+        "Football" to listOf(HobbyCategory.SPORTS, HobbyCategory.OUTDOOR),
+        "Fencing" to listOf(HobbyCategory.SPORTS),
+        "Films and Movies" to listOf(HobbyCategory.ARTS_ENTERTAINMENT),
+        "Gaming and E-sports" to listOf(HobbyCategory.ARTS_ENTERTAINMENT),
+        "Golf" to listOf(HobbyCategory.SPORTS, HobbyCategory.OUTDOOR),
+        "Hip Hop" to listOf(HobbyCategory.ARTS_ENTERTAINMENT),
+        "History" to listOf(HobbyCategory.ACADEMIC_RELATED),
+        "Hockey" to listOf(HobbyCategory.SPORTS, HobbyCategory.OUTDOOR),
+        "Jazz, Soul and Funk" to listOf(HobbyCategory.ARTS_ENTERTAINMENT),
+        "K-pop" to listOf(HobbyCategory.ARTS_ENTERTAINMENT),
+        "Knitting" to listOf(HobbyCategory.ARTS_ENTERTAINMENT),
+        "Lacrosse" to listOf(HobbyCategory.SPORTS, HobbyCategory.OUTDOOR),
+        "Martial Arts" to listOf(HobbyCategory.SPORTS),
+        "Model United Nations" to listOf(HobbyCategory.ACADEMIC_RELATED),
+        "Mountaineering" to listOf(HobbyCategory.OUTDOOR),
+        "Musical Theatre" to listOf(HobbyCategory.ARTS_ENTERTAINMENT),
+        "Netball" to listOf(HobbyCategory.SPORTS, HobbyCategory.OUTDOOR),
+        "Orchestra" to listOf(HobbyCategory.ARTS_ENTERTAINMENT),
+        "Photography" to listOf(HobbyCategory.ARTS_ENTERTAINMENT),
+        "Poker" to listOf(HobbyCategory.SOCIAL),
+        "Pokemon" to listOf(HobbyCategory.SOCIAL),
+        "Radio" to listOf(HobbyCategory.ARTS_ENTERTAINMENT),
+        "Rail and Transport" to listOf(HobbyCategory.SOCIAL),
+        "Robotics" to listOf(HobbyCategory.ACADEMIC_RELATED),
+        "Rugby" to listOf(HobbyCategory.SPORTS, HobbyCategory.OUTDOOR),
+        "Science Fiction and Fantasy" to listOf(HobbyCategory.ARTS_ENTERTAINMENT),
+        "Skating" to listOf(HobbyCategory.SPORTS, HobbyCategory.OUTDOOR),
+        "Snooker and Pool" to listOf(HobbyCategory.SPORTS),
+        "Squash" to listOf(HobbyCategory.SPORTS),
+        "Tabletop Gaming" to listOf(HobbyCategory.ARTS_ENTERTAINMENT),
+        "Tennis" to listOf(HobbyCategory.SPORTS, HobbyCategory.OUTDOOR),
+        "Volleyball" to listOf(HobbyCategory.SPORTS, HobbyCategory.OUTDOOR)
+    )
+
     @Deprecated("Deprecated in Java")
     override fun onBackPressed() {
         // Remove back press option, to prevent double updates to database
     }
 
+    @SuppressLint("MissingInflatedId")
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
         setContentView(R.layout.activity_interest)
@@ -32,6 +98,10 @@ class InterestActivity : AppCompatActivity() {
         // Select interest from drop down list
         val spinner: Spinner = findViewById(R.id.spinner)
         var selectedInterest = ""
+        val adapter = ArrayAdapter(this, android.R.layout.simple_spinner_item, hobbiesCategoriesMap.keys.toList())
+        adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item)
+        spinner.adapter = adapter
+
         spinner.onItemSelectedListener = object : AdapterView.OnItemSelectedListener {
             override fun onItemSelected(parent: AdapterView<*>?, view: View?, position: Int, id: Long) {
                 selectedInterest = spinner.selectedItem as String
@@ -42,6 +112,51 @@ class InterestActivity : AppCompatActivity() {
             }
         }
 
+        val filterSpinner: Spinner = findViewById(R.id.filter_spinner)
+        filterSpinner.onItemSelectedListener = object : AdapterView.OnItemSelectedListener {
+            override fun onItemSelected(parent: AdapterView<*>?, view: View?, position: Int, id: Long) {
+                val category = filterSpinner.selectedItem as String
+                if (category == "None") {
+                    val adapter = ArrayAdapter(this@InterestActivity, android.R.layout.simple_spinner_item, hobbiesCategoriesMap.keys.toList())
+                    adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item)
+                    spinner.adapter = adapter
+                } else {
+                    var categoryToFilter: HobbyCategory? = null
+                    when (category) {
+                        "Academic related" -> {
+                            categoryToFilter = HobbyCategory.ACADEMIC_RELATED
+                        }
+                        "Arts & Entertainment" -> {
+                            categoryToFilter = HobbyCategory.ARTS_ENTERTAINMENT
+                        }
+                        "Charitable" -> {
+                            categoryToFilter = HobbyCategory.CHARITABLE
+                        }
+                        "Indoor" -> {
+                            categoryToFilter = HobbyCategory.INDOOR
+                        }
+                        "Outdoor" -> {
+                            categoryToFilter = HobbyCategory.OUTDOOR
+                        }
+                        "Social" -> {
+                            categoryToFilter = HobbyCategory.SOCIAL
+                        }
+                        "Sports" -> {
+                            categoryToFilter = HobbyCategory.SPORTS
+                        }
+                    }
+                    val adapter = ArrayAdapter(this@InterestActivity, android.R.layout.simple_spinner_item, hobbiesCategoriesMap.filter { it.value.contains(categoryToFilter) }.keys.toList())
+                    adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item)
+                    spinner.adapter = adapter
+                }
+                adapter.notifyDataSetChanged()
+            }
+
+            override fun onNothingSelected(parent: AdapterView<*>?) {
+                // Handle no selection
+            }
+        }
+
         // Add new interest to list of selected interests
         val addInterestButton = findViewById<Button>(R.id.add_new_interest_button)
         addInterestButton.setOnClickListener {
diff --git a/app/src/main/java/com/example/drp25/matchers/MyMatcher.kt b/app/src/main/java/com/example/drp25/matchers/MyMatcher.kt
index 0213c15..844d4ec 100644
--- a/app/src/main/java/com/example/drp25/matchers/MyMatcher.kt
+++ b/app/src/main/java/com/example/drp25/matchers/MyMatcher.kt
@@ -14,8 +14,8 @@ class MyMatcher : Matcher {
         // Check not already matched
         val user2Id = user2Snapshot.key
         val matched1Ref = user1Snapshot.child("matched")
-        for (child in matched1Ref.children) {
-            if (child.value == user2Id) return false
+        for (match in matched1Ref.children) {
+            if (match.child("matchId").value == user2Id) return false
         }
 
         val interests1Ref = user1Snapshot.child("interests")
diff --git a/app/src/main/res/layout/activity_interest.xml b/app/src/main/res/layout/activity_interest.xml
index c5aa0d7..aa50180 100644
--- a/app/src/main/res/layout/activity_interest.xml
+++ b/app/src/main/res/layout/activity_interest.xml
@@ -6,6 +6,17 @@
     android:layout_height="match_parent"
     tools:context=".InterestActivity">
 
+    <TextView
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:layout_marginTop="@dimen/text_margin_32"
+        android:layout_marginHorizontal="56dp"
+        android:text="Select your interest!"
+        android:textColor="@color/stream_ui_accent_red"
+        android:textSize="20sp"
+        app:layout_constraintTop_toBottomOf="@id/back_button_interests"
+        app:layout_constraintBottom_toTopOf="@id/spinner"/>
+
     <Spinner
         android:id="@+id/spinner"
         android:layout_width="match_parent"
@@ -13,7 +24,6 @@
         android:layout_marginStart="56dp"
         android:layout_marginTop="32dp"
         android:layout_marginEnd="56dp"
-        android:entries="@array/interest_array"
         android:hint="@string/interest_prompt"
         android:maxWidth="360dp"
         android:minHeight="48dp"
@@ -21,6 +31,30 @@
         app:layout_constraintStart_toStartOf="parent"
         app:layout_constraintTop_toBottomOf="@+id/back_button_interests" />
 
+    <TextView
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:layout_marginTop="@dimen/text_margin_32"
+        android:layout_marginHorizontal="56dp"
+        android:text="Filter by..."
+        android:textSize="20sp"
+        app:layout_constraintTop_toBottomOf="@id/spinner"
+        app:layout_constraintBottom_toTopOf="@id/filter_spinner"/>
+
+    <Spinner
+        android:id="@+id/filter_spinner"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:layout_marginStart="56dp"
+        android:layout_marginTop="32dp"
+        android:layout_marginEnd="56dp"
+        android:entries="@array/category_array"
+        android:hint="Choose a category to filter by"
+        android:maxWidth="360dp"
+        android:minHeight="48dp"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintTop_toBottomOf="@+id/spinner" />
 
     <com.google.android.material.chip.ChipGroup
         android:id="@+id/interests_group"
@@ -45,7 +79,7 @@
         android:text="@string/add_new_interest"
         app:layout_constraintEnd_toEndOf="parent"
         app:layout_constraintStart_toStartOf="parent"
-        app:layout_constraintTop_toBottomOf="@+id/spinner" />
+        app:layout_constraintTop_toBottomOf="@+id/filter_spinner" />
 
     <Button
         android:id="@+id/back_button_interests"
diff --git a/app/src/main/res/values/strings.xml b/app/src/main/res/values/strings.xml
index b92a0de..8fda828 100644
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
@@ -134,7 +134,7 @@
         <item>Musical Theatre</item>
         <item>Netball</item>
         <item>Orchestra</item>
-        <item>Photography</item>
+        <item>Ph otography</item>
         <item>Poker</item>
         <item>Pokemon</item>
         <item>Radio</item>
@@ -149,6 +149,16 @@
         <item>Tennis</item>
         <item>Volleyball</item>
     </string-array>
+    <string-array name="category_array">
+        <item>None</item>
+        <item>Academic related</item>
+        <item>Arts &amp; Entertainment</item>
+        <item>Charitable</item>
+        <item>Indoor</item>
+        <item>Outdoor</item>
+        <item>Social</item>
+        <item>Sports</item>
+    </string-array>
     <string name="title_activity_club_interest">ClubInterestActivity</string>
     <string name="large_text">
         "Material is the metaphor.\n\n"