Prefer List/Map/Set as declaring type over their implementations

Unless your are using a method declared in subclasses of an
interface, it is better to use the interface as declaring type.
One advantage of this is that changing used implementation will
be much simpler (you will have less declarations to edit).

app/src/main/java/com/topjohnwu/magisk/adapters/PolicyAdapter.java

@@ -21,6 +21,7 @@ import com.topjohnwu.magisk.utils.Utils;
 
 import java.util.HashSet;
 import java.util.List;
+import java.util.Set;
 
 import butterknife.BindView;
 import butterknife.ButterKnife;
@@ -30,7 +31,7 @@ public class PolicyAdapter extends RecyclerView.Adapter<PolicyAdapter.ViewHolder
     private List<Policy> policyList;
     private SuDatabaseHelper dbHelper;
     private PackageManager pm;
-    private HashSet<Policy> expandList = new HashSet<>();
+    private Set<Policy> expandList = new HashSet<>();
 
     public PolicyAdapter(List<Policy> list, SuDatabaseHelper db, PackageManager pm) {
         policyList = list;

app/src/main/java/com/topjohnwu/magisk/adapters/ReposAdapter.java

@@ -24,6 +24,7 @@ import com.topjohnwu.magisk.utils.WebWindow;
 
 import java.util.HashSet;
 import java.util.List;
+import java.util.Set;
 
 import butterknife.BindView;
 import butterknife.ButterKnife;
@@ -31,7 +32,7 @@ import butterknife.ButterKnife;
 public class ReposAdapter extends RecyclerView.Adapter<ReposAdapter.ViewHolder> {
 
     private List<Repo> mUpdateRepos, mInstalledRepos, mOthersRepos;
-    private HashSet<Repo> expandList = new HashSet<>();
+    private Set<Repo> expandList = new HashSet<>();
 
     public ReposAdapter(List<Repo> update, List<Repo> installed, List<Repo> others) {
         mUpdateRepos = update;

app/src/main/java/com/topjohnwu/magisk/adapters/SuLogAdapter.java

@@ -22,10 +22,11 @@ import com.topjohnwu.magisk.R;
 import com.topjohnwu.magisk.superuser.SuLogEntry;
 
 import java.util.ArrayList;
-import java.util.HashMap;
 import java.util.HashSet;
 import java.util.LinkedHashMap;
 import java.util.List;
+import java.util.Map;
+import java.util.Set;
 
 import butterknife.BindView;
 import butterknife.ButterKnife;
@@ -33,13 +34,13 @@ import butterknife.ButterKnife;
 public class SuLogAdapter {
 
     private ExpandableAdapter adapter;
-    private HashSet<SuLogEntry> expandList = new HashSet<>();
+    private Set<SuLogEntry> expandList = new HashSet<>();
 
     public SuLogAdapter(List<SuLogEntry> list) {
 
         // Separate the logs with date
-        LinkedHashMap<String, ArrayList<SuLogEntry>> logEntryMap = new LinkedHashMap<>();
+        Map<String, List<SuLogEntry>> logEntryMap = new LinkedHashMap<>();
-        ArrayList<SuLogEntry> group;
+        List<SuLogEntry> group;
         for (SuLogEntry log : list) {
             String date = log.getDateString();
             group = logEntryMap.get(date);
@@ -51,8 +52,8 @@ public class SuLogAdapter {
         }
 
         // Then format them into expandable groups
-        ArrayList<LogGroup> logEntryGroups = new ArrayList<>();
+        List<LogGroup> logEntryGroups = new ArrayList<>();
-        for (HashMap.Entry<String, ArrayList<SuLogEntry>> entry : logEntryMap.entrySet()) {
+        for (Map.Entry<String, List<SuLogEntry>> entry : logEntryMap.entrySet()) {
             logEntryGroups.add(new LogGroup(entry.getKey(), entry.getValue()));
         }
         adapter = new ExpandableAdapter(logEntryGroups);

app/src/main/java/com/topjohnwu/magisk/module/ModuleHelper.java

@@ -24,6 +24,7 @@ import java.util.Date;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Locale;
+import java.util.Map;
 
 public class ModuleHelper {
 
@@ -70,7 +71,7 @@ public class ModuleHelper {
             jsonString = prefs.getString(REPO_KEY, null);
         }
 
-        ValueSortedMap<String, Repo> cached = null;
+        Map<String, Repo> cached = null;
 
         if (jsonString != null) {
             cached = gson.fromJson(jsonString, new TypeToken<ValueSortedMap<String, Repo>>(){}.getType());
@@ -82,7 +83,7 @@ public class ModuleHelper {
 
         // Get cached ETag to add in the request header
         String etag = prefs.getString(ETAG_KEY, "");
-        HashMap<String, String> header = new HashMap<>();
+        Map<String, String> header = new HashMap<>();
         header.put("If-None-Match", etag);
 
         // Making a request to main URL for repo info

app/src/main/java/com/topjohnwu/magisk/utils/CallbackHandler.java

@@ -2,13 +2,15 @@ package com.topjohnwu.magisk.utils;
 
 import java.util.HashMap;
 import java.util.HashSet;
+import java.util.Map;
+import java.util.Set;
 
 public class CallbackHandler {
 
-    private static HashMap<Event, HashSet<EventListener>> listeners = new HashMap<>();
+    private static Map<Event, Set<EventListener>> listeners = new HashMap<>();
 
     public static void register(Event event, EventListener listener) {
-        HashSet<EventListener> list = listeners.get(event);
+        Set<EventListener> list = listeners.get(event);
         if (list == null) {
             list = new HashSet<>();
             listeners.put(event, list);
@@ -17,21 +19,21 @@ public class CallbackHandler {
     }
 
     public static void unRegister(Event event) {
-        HashSet<EventListener> list = listeners.remove(event);
+        Set<EventListener> list = listeners.remove(event);
         if (list != null) {
             list.clear();
         }
     }
 
     public static void unRegister(Event event, EventListener listener) {
-        HashSet<EventListener> list = listeners.get(event);
+        Set<EventListener> list = listeners.get(event);
         if (list != null) {
             list.remove(listener);
         }
     }
 
     private static void triggerCallback(Event event) {
-        HashSet<EventListener> list = listeners.get(event);
+        Set<EventListener> list = listeners.get(event);
         if (list != null) {
             for (EventListener listener : list) {
                 listener.onTrigger(event);